the salmon louse , lepeophtheirus salmonis , is a species of copepod in the genus lepeophtheirus .

it is a sea louse , a parasite living mostly on salmon , particularly on pacific and atlantic salmon and sea trout , but is also sometimes found on the three-spined stickleback .

it lives off the mucus , skin and blood of the fish .

they are natural marine parasites of fish such as adult salmon .

once detached they can be blown by wind across the surface of the sea , like plankton .

when they encounter a suitable marine fish host they may adhere themselves to the skin , fins , the gills of the fish , and feeding off the mucus or skin .

sea lice only affect fish and are not harmful towards humans .

salmon lice are natural ectoparasites of salmon , in the 1980s high levels of salmon lice were observed on pink salmon smolts .

salmon lice are found in pacific and atlantic oceans , they infect pink salmon , atlantic salmon , and chum salmon .

salmon louse

sea louse abundance over time on atlantic salmon on named salmon farms in the discovery islands .
] described the parasite as having two cycles of development in the atlantic salmon and one in the salmon louse . transmission mechanisms between atlantic salmon and
the effect of light on the settlement of the salmon louse , lepeophtheirus salmonis , on atlantic salmon , salmo salar l .
jakob e , sweeten t , bennett w , jones srm . development of the salmon louse
was significantly reduced by a single sea louse once it reached chalimus 3 stage ( where both louse and salmon developed together ) provided the pink salmon was less than 0 . 34 g . impaired
jones s , kim e , bennett w . early development of resistance to the salmon louse ,
the salmon louse lepeophtheirus salmonis ( copepoda : caligidae ) life cycle has only two chalimus stages .
] was used to assess the effect of different salmon louse loads and developmental stages on swimming performance .
indicated that atlantic salmon is the most desirable host compared coho or sockeye salmon .
the effect of light on the settlement of the salmon louse , lepeophtheirus salmonis , on atlantic salmon , salmo salar l . - pubmed - ncbi
the characteristics of the transcriptomic response to atlantic salmon suggest increased parasite fitness . host blood is a main dietary component of the adult female salmon louse [
when the louse is in the chalimus stage it is smaller than the juvenile louse at the bottom of the photo at the right .
animals with an exoskeleton , like the salmon louse , grow through molting and each instar typically shows limited increase in size . developmental stages in salmon louse ( 3 free - living and 7 parasitic ) are also separated by molting [
) . therefore , as predicted , a salmon louse created an ionic burden for tiny pink salmon once the louse approached the pre - adult stage . furthermore , this burden increased in intensity and occurred earlier with additional lice . following this , ionic impact through to the adult stage of the louse was precluded by the ability of pink salmon to shed salmon lice ( discussed further below ) .
an evaluation of the impact of early infestation with the salmon louse lepeophtheirus salmonis on the subsequent survival of outwardly migrating atlantic salmon , salmo salar l . , smolts
despite thorough controls we cannot rule out that a salmon louse can make it to the market , ” continues breiland .
] . furthermore , coevolution of the pacific louse subspecies with pacific salmon for between 4 . 6 and 11 ma [
the salmon louse lepeophtheirus salmonis ( copepoda : caligidae ) life cycle has only two chalimus stages . - pubmed - ncbi
comment on beamish et al . “a proposed life history strategy for the salmon louse , lepeophtheirus salmonis in the subarctic pacific
the chalimus stage is a period when the salmon louse attaches itself to the fish but is still very , very tiny .
eichner c , frost p , dysvik b , jonassen i , kristiansen b et al . ( 2008 ) salmon louse (
include a th2 - type response at the louse - salmon interface . dev comp immunol . 2015 ; 48 : 178–91 .
according to the researchers , it has now been established that the salmon louse chalimus larvae also expand in size between molts .
protein was significantly overexpressed in the feeding salmon louse transcriptome , and most highly by parasites feeding on atlantic salmon . saposin - like proteins ( saplips ) have been described from
pink salmon , oncorhynchus gorbuscha , are the most abundant wild salmon species and are thought of as an indicator of ecosystem health . the salmon louse , lepeophtheirus salmonis , is endemic to pink salmon habitat but these ectoparasites have been implicated in reducing local pink salmon populations in the broughton archipelago , british columbia . this allegation arose largely because juvenile pink salmon migrate past commercial open net salmon farms , which are known to incubate the salmon louse . juvenile pink salmon are thought to be especially sensitive to this ectoparasite because they enter the sea at such a small size ( approx . 0 . 2 g ) . here , we describe how ‘no effect’ thresholds for salmon louse sublethal impacts on juvenile pink salmon were determined using physiological principles . these data were accepted by environmental managers and are being used to minimize the impact of salmon aquaculture on wild pink salmon populations .
originally , the salmon louse was described to have nine larval stages , but a new study shows that it only has seven .
among salmon louse loads of 1 , 2 , 3 or more lice / fish . even so , the magnitude of the reduction in
the differing host responses to the salmon louse suggest that there are also host - specific parasite responses . behavioural studies indicate a preference of
tadiso tm , krasnov a , skugor s , afanasyev s , hordvik i , nilsen f . gene expression analyses of immune responses in atlantic salmon during early stages of infection by salmon louse (
tadiso tm , krasnov a , skugor s , afanasyev s , hordvik i , nilsen f . gene expression analyses of immune responses in atlantic salmon during early stages of infection by salmon louse (
include a th2 - type response at the louse - salmon interface . dev comp immunol . 2015 ; 48 ( 1 ) : 178–91 .
salmon lice are endemic to the broughton archipelago , and are brought back to the system by returning adult salmon . whether out - migrating juvenile pink salmon have been historically exposed to the salmon louse at such a high level of prevalence and intensity as was observed in 2001 is unclear . the necessary detailed records simply do not exist , but given the decline to the current levels of salmon louse infection ( 10 % of juvenile pink salmon are infected with one louse [ 61 ] ) , we are left with three possibilities : an unusual epizooitic , a high infection driven by incubation on salmon in net - pens , or a combination .
‘they are everywhere now , and just a few can kill a fish’ … the lepeophtheirus salmonis , or the common salmon louse . photograph : alamy
laboratory - reared strains of salmon louse were used . infectious copepodids are produced in small buckets with flow - through water , starting with egg strings . the copepodids are allowed to infect naive atlantic salmon kept in flow through water tanks . at relevant time points after infection , the salmon is anesthetized and salmon louse of interest collected and conserved for later use . in the present study adult fertilized individuals of
we first provide background to the host ( pink salmon ) , ectoparasite ( salmon louse ) and specific problems identified in the broughton archipelago . we then discuss recent findings from physiological studies that ( i ) provided much needed basic background information on the unique life history of juvenile pink salmon , and ( ii ) investigated the interaction between the salmon louse and pink salmon using a combination of laboratory and field studies . we specifically address the questions : do sea louse infections impair the fitness of juvenile pink salmon ? and if so , what are the negative impacts and at what level of infection are impacts seen ?
and in whole - body louse homogenate . j parasitol . 2000 ; 86 : 1199–205 .
' snorkel ' lice barrier technology reduced two co - occurring parasites , the salmon louse ( lepeophtheirus salmonis ) and the amoebic gill disease causing agent ( neoparamoeba perurans ) , in commercial salmon sea - cages .
new results have shown that the salmon louse has seven larval stages before it develops into an adult . previously , nine larval stages have been described . as the louse undergoes ecdysis between each stage , the number of molts has also been reduced .
holm h , santi n , kjøglum s , perisic n , skugor s , evensen ø . difference in skin immune responses to infection with salmon louse (
good disease control is therefore crucial . marit stormoen ' s phd project focuses on the control of pancreas disease and salmon louse in the norwegian aquaculture industry .
it is not surprising that at some point salmon louse will impair swimming performance ; however , whether this impairment is seen at ecologically relevant levels of infection is of primary interest . again , the life histories of both the salmon louse and pink salmon are complex and thus the possibility for types of infection vary widely , from juveniles being infected with adult salmon lice resulting in immediate effects , to those where pinks and salmon lice interact early in development and then grow together over a long duration .
mordue aj , birkett ma . a review of host finding behaviour in the parasitic sea louse ,
as the louse undergoes ecdysis between each stage , the number of molts has also been reduced .
the experiments were carried out on salmon louse lepeophtheirus salmonis whereas atlantic salmon ( salmo salar ) , lumpfish ( cyclopterus lumpus ) and ballan wrasse ( labrus bergylta ) were used only as a host for the experimental animals .
dalvin s , frost p , loeffen p , skern - mauritzen r , baban j et al . ( 2011 ) characterisation of two vitellogenins in the salmon louse
new results have shown that the salmon louse has seven larval stages before it develops into an adult . previously , nine larval stages have been described by scientists .
one of the reasons why the new studies were initiated was that the salmon louse appeared to have an unusually large number of larval stages compared to related animals .
perhaps the only study that has truly considered the impact of salmon louse infection on juvenile salmon is the 10 - year study of the return of atlantic salmon smolts that had been treated with slice ( emamectin benzoate ) to protect them from salmon louse infection for the first 90 days of their outward migration , a period which easily extended beyond the contact with net - pen aquaculture and associated salmon lice . remarkably , a comparison with non - treated fish revealed that protection of juveniles from salmon louse infection represented a minor component to overall marine survival . indeed , during the 10 - year study , adult atlantic salmon returns fell a similar 10 - fold in both treated and non - treated fish [ 71 ] . a similar study on juvenile pink salmon treated with slice in the broughton archipelago could be very revealing in assessing the true impact of sea lice on pink salmon fitness .
johnson sc , blaylock rb , elphick j , hyatt kd . disease induced by the sea louse (
one of our readers wonders whether she has found a salmon louse on a filet she bought in a supermarket . can these creatures really end up on your plate ?
mennerat a , hamre l , ebert d , nilsen f , dávidová m et al . ( 2012 ) life history and virulence are linked in the ectoparasitic salmon louse
protein coding genes are classified as
function unknown
. currently , no copepod genome has been sequenced and the closest sequenced relatives to the salmon louse are insects like
connors bm , krkosek m , ford j , dill lm ( 2010 ) coho salmon productivity in relation to salmon lice from infected prey and salmon farms . j appl ecol 47 : 1372–1377 .
the salmon louse is an external parasite found naturally on wild salmonids . the increased pressure of salmon lice infestations on wild fish over recent years has lead to extensive , negative consequences , especially for sea trout . this film describes nina’s monitoring of salmon lice on wild salmonids in the summer of 2014 .
] . pink salmon enter sw precociously in that a large increase in whole body ions is observed following sw entry , which is gradually corrected probably as a result of increased gill nka expression which increasingly favours the sw isoform over the fw isoform . the management implication of these results is fairly obvious . deliberately delaying sw entry of pink salmon to potentially increase body size and minimize salmon louse impacts is unlikely to be useful as a management tool because mortality would increase independent of salmon louse infection once juvenile pink salmon pass their smoltification window .
wild salmon get their colour from eating krill and shrimp . the flesh of farmed salmon is grey , and is coloured by astaxanthin , a manufactured copy of the pigment that wild salmon eat in nature
: characterization of prostaglandin e ( 2 ) in secretory products of the salmon louse by rp - hplc and mass spectrometry . exp parasitol . 2004 ; 107 : 5–13 .
] . our study quantified the direct impact of the salmon louse on relevant and sensitive life - history stages of juvenile wild pink salmon , which were then used to promote informed policy decisions for the sustainable coexistence of farmed and wild fish .
this photo shows an adult female louse with eggs ( top ) , an adult female without eggs ( middle ) and a juvenile louse ( bottom ) . the lice in the stage that øines indicates are smaller than this young louse . ( photo : thomas bjørkan / wikimedia / cc by - sa 3 . 0 )
) . upon sampling , each louse was individually snap - frozen in liquid nitrogen for gene expression profiling .
maldonado - aguayo w , chávez - mardones j , gonçalves at , gallardo - escárate c . cathepsin gene family reveals transcriptome patterns related to the infective stages of the salmon louse
' snorkel ' lice barrier technology reduced two co - occurring parasites , the salmon louse ( lepeophtheirus salmonis ) and the amoebic gill disease caus . . . - pubmed - ncbi
price mh , proboszcz sl , routledge rd , gottesfeld as , orr c et al . ( 2011 ) sea louse infection of juvenile sockeye salmon in relation to marine salmon farms on canada’s west coast . plos one 6 : e16851 . doi :
] , the management implication of this work is that up to 10 per cent of the juvenile pink salmon in the broughton archipelago may exhibit sublethal effects of salmon louse exposure . however , what this ultimately means in terms of fish survival remains unknown [
skugor s , glover ka , nilsen f , krasnov a . local and systemic gene expression responses of atlantic salmon ( salmo salar l . ) to infection with the salmon louse ( lepeophtheirus salmonis ) . bmc genomics . 2008 ; 9 : 498 .
the spawner–recruitment data span 1970–2009 for populations of pink salmon and coho salmon in the central coast and broughton archipelago region of british columbia . for pink salmon there are 104 populations not exposed to salmon farms and 17 populations exposed to salmon farms . for coho salmon , there are 40 unexposed and 13 exposed populations . the pink salmon data have been described in refs . 12 and 15 , whereas the coho salmon data have been described in ref . 11 . rivers for exposed populations are shown in fig . 1 and the data are further detailed in si methods .
øivind øines says there actually is a very small chance that a salmon louse could end up on a filet bought retail . he is a parasite researcher at the norwegian veterinary institute .
we acknowledge constructive discussion with members of the salmon louse research centre ( slrc ) and institute of marine research , in particular the assistance on data analysis from mette skern - mauritzen .
marine harvest canada ( mhc ) is the only salmon farm company to report sea louse average abundance ; raw sea louse data were not reported publicly at the time of our study . we used average caligus clemensi abundance and l . salmonis motile abundance provided online to estimate sea louse trends on six mhc farms in the discovery islands during 2007–2008 ; sea louse data were not provided for the other 12 farms operating in the region . for periods without reported information , we calculated average abundance using the previous and subsequent values .
salmon lice on sea trout and atlantic salmon salmon lice have always been a natural parasite on wild salmonids . however , during the last years the infestation of salmon lice has increased on wild salmonids causing negative consequences – and especially for sea trout . the film presents salmon lice monitoring on wild salmonids , performed by ninas scientist in the summer of 2014 .
a university of alberta led research team has some positive news for british columbia ' s pink salmon populations , and the salmon farming industry that has struggled to protect both captive and wild salmon from sea lice infestations .
laboratory and field investigations of salmon lice [ lepeophtheirus salmonis ( krøyer ) ] infestation on atlantic salmon ( salmo salar l . ) post - smolts
tucker cs , norman r , shinn ap , bron je , sommerville c et al . ( 2002 ) a single cohort time delay model of the life - cycle of the salmon louse
browman hi , boxaspen k , kuhn p . the effect of light on the settlement of the salmon louse , lepeophtheirus salmonis , on atlantic salmon , salmo salar l . j fish dis . 2004 ; 27 ( 12 ) : 701–8 . pmid : 15575878 .
the level of shedding we observed is not unusual compared with previous studies where pink salmon were artificially infected ( abundance was reduced within 5 to 12 dpi ; [ 44 ] ) or naturally infected pink salmon were held [ 66 , 67 ] . a high rate of louse shedding is also of importance in mathematical models , where the incorporation of realistic shedding rates [ 67 ] reduces the predicted mortality of pink salmon owing to salmon louse infection by 95 % relative to an earlier model where shedding was not considered [ 10 ] . collectively , these findings of high rates of shedding of attached lice suggest that the majority of the salmon lice that successfully infect a fish will be shed before they reach motile and reproductive stages . clearly , the interactions between salmon lice , juvenile pink salmon and their environment are extremely complex and change temporally as both salmon louse and fish develop and the implications of this need to be considered in relation to conservation efforts .
] . this possibility was addressed by conducting a reciprocal host exposure study using lice collected from sockeye salmon or atlantic salmon . in the event of acclimation , we expected an enhanced parasite response when lice were allowed to feed on the species from which they had been collected . however , we consistently observed that lice responded strongly to atlantic salmon , irrespective of the source host species , thus corroborating the host - effect hypothesis and further illustrating the desirability of atlantic salmon to the pacific salmon louse .
krøyer , 1838 ) causes multi - million dollar commercial losses to the salmon farming industry world - wide , and strict lice control regimes have been put in place to reduce the release of salmon louse larvae from aquaculture facilities into the environment . for half a century , the
bailey rje , birkett m , ingvarsdóttir a , luntz jm , mordue w , shea bo , et al . the role of semiochemicals in host location and non - host avoidance by salmon louse (
like genes are not regulated in males . since both group 3 and 2 genes are down regulated after t1 , when the post - molting growth of adult female salmon louse takes place ( see figure
citation : price mhh , proboszcz sl , routledge rd , gottesfeld as , orr c , reynolds jd ( 2011 ) sea louse infection of juvenile sockeye salmon in relation to marine salmon farms on canada ' s west coast . plos one 6 ( 2 ) : e16851 . urltoken
yazawa r , yasuike m , leong j , von schalburg kr , cooper g , beetz - sargent m , et al . est and mitochondrial dna sequences support a distinct pacific form of salmon louse ,
] , which restricts the feeding area . however , in the succeeding pre - ad i and - ii and adult stages the salmon louse can move unrestricted on the host surface resulting in increased virulence [
orr c ( 2007 ) estimated sea louse egg production from marine harvest canada farmed atlantic salmon in the broughton archipelago , british columbia , 2003 - 2004 . n am j fish manage 27 : 187–197 .
lepeophtheirus salmonis , or the common salmon louse , now infests nearly half of scotland’s salmon farms . last year lice killed thousands of tonnes of farmed fish , caused skin lesions and secondary infections in millions more , and cost the scottish industry alone around £300m in trying to control them .
) , indicate that feeding on atlantic salmon was associated with pronounced metabolic activity .
krasnov a , wesmajervi breiland ms , hatlen b , afanasyev s , skugor s . sexual maturation and administration of 17β - estradiol and testosterone induce complex gene expression changes in skin and increase resistance of atlantic salmon to ectoparasite salmon louse . gen comp endocrinol . 2015 ; 212c : 34–43 .
citation : komisarczuk az , grotmol s , nilsen f ( 2017 ) ionotropic receptors signal host recognition in the salmon louse ( lepeophtheirus salmonis , copepoda ) . plos one 12 ( 6 ) : e0178812 . urltoken
this study characterized global transcriptomic responses of pacific salmon lice during infection of susceptible and resistant hosts . similar parasite responses during infection of coho or sockeye salmon , despite differences in natural immunity to infection between these host species , indicate that host susceptibility status alone does not drive the parasite response . we identified an enhanced louse response after feeding on atlantic salmon , characterized by up - regulation of virulence factors , energy metabolism and reproductive - associated transcripts . in contrast , the responses of lice infecting coho or sockeye salmon were weaker , with reduced expression of virulence factors . these observations indicate that the response of the louse is independent of host susceptibility and suggest that co - evolutionary host - parasite relationships may influence contemporary host - parasite interactions . this research improves our understanding of the susceptibility of atlantic salmon and may assist in the development of novel control measures against the salmon louse .
a salmon louse is very tiny when it attaches itself to a fish . this photo shows a fully grown female louse . the long , beige anterior threads contain eggs , which she releases into the water . new lice hatch and float around until they come across a host to attach to . ( photo : marit hommedal / ntb scanpix )
grimnes a , jakobsen pj . the physiological effects of salmon lice infection on post - smolt of atlantic salmon . journal fish biol . 1996 ; 48 : 1179–94 .
salmon lice have become a big problem for wild as well as farmed salmon . the parasites attach themselves to the salmon and live off the host’s blood , skin and slime . they can cause large sores and make the fish more vulnerable to infections .
the atlantic salmon , salmo salar l , is an important species both for traditional fishery and fish farming . many atlantic salmon stocks have been declining and a suspected main contributor to this decline is the salmon louse ( lepeophtheirus salmonis ) ; a parasitic copepod living off the salmonid hosts epidermal tissues and blood . contributing to the growing body of knowledge on the molecular biology of the salmon louse we have utilized a microarray containing 11 , 100 salmon louse genes to study the gene expression patterns in selected tissues . this approach has yielded information about potential functions of the transcripts and tissues . microarray analyses were preformed on subcuticular and frontal ( neuronal and gland enriched tissue ) tissues , as well as gut , ovary and testes of adult lice . tissue specific transcriptomes were evident , allowing us to address main traits of functional partitioning between tissues and providing valuable insight into the biology of the louse . the results furthermore represent an important tool and resource for further experiments .
outcomes of infections with the salmon louse lepeophtheirus salmonis vary considerably among its natural hosts ( salmo , oncorhynchus spp . ) . host - parasite interactions range from weak to strong host responses accompanied by high to low parasite abundances , respectively . parasite behavioral studies indicate that the louse prefers the host atlantic salmon ( salmo salar ) , which is characterized by a weak immune response , and that this results in enhanced parasite reproduction and growth rates . furthermore , parasite - derived immunosuppressive molecules ( e . g . , proteases ) have been detected at higher amounts in response to the mucus of atlantic salmon relative to coho salmon ( oncorhynchus kisutch ) . however , the host - specific responses of the salmon louse have not been well characterized in either of the genetically distinct sub - species that occur in the atlantic and pacific oceans .
our results show that survival is negatively correlated with abundance of lice on salmon farms , for both pink and coho salmon . this is consistent with previous analyses of spawner–recruit data for both species that used a multistock approach that used a fixed factor to group years when infestations of wild juvenile salmon were observed relative to years before infestations were observed ( 11 , 12 ) . our results here , which instead treat abundance of lice on farmed salmon as a time - varying covariate , indicate a direct link between survival and louse abundance on farms . however , this approach also reveals that the magnitude of the estimated effect of lice is sensitive to assumptions on the spatial distribution of lice among farms and the migration routes of wild juvenile salmon . further work is needed on juvenile salmon migration routes and timing to quantitatively link farm location , louse abundance , and salmon survival .
the scientific ( latin ) name of this creature is lepeophteirus salmonis . this parasite lives in salt water on salmon in the northern hemisphere . the louse has a diameter of 3–5 millimetres . these pictures have been coloured .
lepeophtheirus salmonis , the salmon louse , occurs in cold temperate waters of the northern hemisphere . l . salmonis is an ectoparasite which occur on all salmonid species ; salmon , trout and char . they may be found on other fish species as a stop - gap measure while seeking out their salmonid host .
each year the salmon louse ( lepeophtheirussalmonis krøyer , 1838 ) causes multi - million dollar commercial losses to the salmon farming industry world - wide , and strict lice control regimes have been put in place to reduce the release of salmon louse larvae from aquaculture facilities into the environment . for half a century , the lepeophtheirus life cycle has been regarded as the only copepod life cycle including 8 post - nauplius instars as confirmed in four different species , including l . salmonis . here we prove that the accepted life cycle of the salmon louse is wrong . by observations of chalimus larvae molting in incubators and by morphometric cluster analysis , we show that there are only two chalimus instars : chalimus 1 ( comprising the former chalimus i and ii stages which are not separated by a molt ) and chalimus 2 ( the former chalimus iii and iv stages which are not separated by a molt ) . consequently the salmon louse life cycle has only six post - nauplius instars , as in other genera of caligid sea lice and copepods in general . these findings are of fundamental importance in experimental studies as well as for interpretation of salmon louse biology and for control and management of this economically important parasite .
each year the salmon louse ( lepeophtheirus salmonis krøyer , 1838 ) causes multi - million dollar commercial losses to the salmon farming industry world - wide , and strict lice control regimes have been put in place to reduce the release of salmon louse larvae from aquaculture facilities into the environment . for half a century , the lepeophtheirus life cycle has been regarded as the only copepod life cycle including 8 post - nauplius instars as confirmed in four different species , including l . salmonis . here we prove that the accepted life cycle of the salmon louse is wrong . by observations of chalimus larvae molting in incubators and by morphometric cluster analysis , we show that there are only two chalimus instars : chalimus 1 ( comprising the former chalimus i and ii stages which are not separated by a molt ) and chalimus 2 ( the former chalimus iii and iv stages which are not separated by a molt ) . consequently the salmon louse life cycle has only six post - nauplius instars , as in other genera of caligid sea lice and copepods in general . these findings are of fundamental importance in experimental studies as well as for interpretation of salmon louse biology and for control and management of this economically important parasite .
the salmon farming industry has grown at breakneck speed since the 1970s . photograph : alamy
marty gd , saksida sm , quinn tj ( 2010 ) relationship of farm salmon , sea lice , and wild salmon populations . proc natl acad sci u s a .
hamre la , glover ka , nilsen f . establishment and characterisation of salmon louse ( lepeophtheirus salmonis ( kroyer 1837 ) ) laboratory strains . parasitology international . 2009 ; 58 ( 4 ) : 451–60 . pmid : 19732850 .
given the different levels of support for the four infection scenarios ( table 2 ) , we estimated the louse - induced mortality of pink and coho salmon for each scenario . there was substantial variation in the magnitude of estimated louse effect , c , among scenarios ( table 2 ) . the estimated mortality of wild salmon due to sea lice from salmon farms per generation of salmon is 1 − exp ( cl t + τ ) . these estimates suggest mortality from farm lice is biologically significant ( fig . 2 ) —sometimes large , but variable among scenarios and years due to variation in louse abundance and uncertainty in c ( tables 1 and 2 ) . for pink salmon , estimated mortality ranged from 88 % when lice were abundant down to 1 % when lice were less abundant . for coho salmon , estimated mortality reached 92 % when sea lice were abundant and was as low as 2 % when lice were rare ( table 3 ) .
peptidases from the different families may be involved in a wide range of cellular and biological processes making it difficult to infer the function based on database searches . host blood is a major component of the food for the salmon louse [
hamre urltoken the salmon louse lepeophtheirus salmonis ( copepoda : caligidae ) life cycle has only two chalimus stages , plosone 8 ( 9 ) . sept 12 , 2013 , doi : 10 . 1371 / journal . pone . 0073539 .
nylund a , watanabe k , nylund s , sævareid i , arnesen ce , karlsbakk e : salmon louse : a biological vector for a salmonid parasite . naturen . 2009 , 133 : 217 - 222 . ( in norwegian )
the results of the reproduction study were incorporated into a dynamic model with the aim of predicting the optimum louse density for treatment and how far this would affect the areas around the fish farms with regard to the total production of louse eggs . stormoen found the louse density on a farm is primarily driven by autoinfection but is triggered in the first instance by infection from nearby farms and possibly by infection from wild fish . this indicates that fish farms should keep louse density low at all times in order to reduce as much as possible the infection of neighbouring wild fish .
as the salmon farming industry has grown , the infestations of salmon lice have multiplied in coastal areas with aquaculture . salmon lice infestations can result in increased susceptibility to disease , reduced growth , and increased mortality in host fish . favourable conditions for the salmon lice ahead of the smolt migration may intensify the infection pressure at this critical stage for atlantic salmon . at the same time sea trout and arctic charr may experience a prolonged increase in infection pressure .
a laboratory strain of salmon louse ( lepeophtheirus salmonis ) was used in all experiments [ 33 ] and was maintained on farmed atlantic salmon ( salmo salar ) in sea water ( 34 . 5 ‰ ) at 10°c . before infection , salmon louse were hatched and cultivated to copepodid stage in single well , flow - through incubators , with water supply from the same source [ 33 ] . prior to lice sampling , the salmon were anaesthetized in a mixture of methomidate ( 5mg / l ) and benzocaine ( 60mg / l ) and lice removed with forceps [ 33 ] . all experimental procedures were performed according to the norwegian animal welfare legislation .
haugland m , holst jc , holm m , hansen lp . feeding of atlantic salmon (
salmon louse infections produce epidermal lesions , ionoregulatory disruptions and secondary infections in salmon [ 33 ] . ionoregulatory disruptions have been observed following artificial infection in larger salmonids : brown trout smolts ( salmo trutta , 40 g [ 34 ] , 90 g [ 35 ] ) , atlantic salmon post - smolts ( salmo salar , 40–60 g [ 36 – 38 ] ) and atlantic salmon adults ( s . salar , 600 g [ 39 ] ) . thus , the working hypothesis for pink salmon that were 100 - to 1000 - times smaller was that the physiological mechanism ( s ) through which juvenile pink salmon are affected by the salmon louse has its origin as an ionoregulatory disturbance . furthermore , the extent of this ionoregulatory disturbance would be in proportion to the parasite load on the fish , i . e . the greater the number of parasites , the greater the damage to the epidermal barrier and the greater the ionoregulatory disturbance .
frost p , nilsen f . validation of reference genes for transcription profiling in the salmon louse , lepeophtheirus salmonis , by quantitative real - time pcr . veterinary parasitology . 2003 ; 118 ( 1–2 ) : 169–74 . pmid : 14651887 .
maximum swimming performance ( u max ) of glendale river - caught fish artificially infected with l . salmonis copepodids . control fish ( black solid line ) and fish with salmon louse infection intensity of one ( mid - grey , dashed ) , two ( dark grey ) , three ( light grey ) and all infection intensities pooled ( black dashed line ) . an asterisk ( * ) denotes significant differences between control and infected ( pooled or individual ) values , while discontinuous horizontal lines denote a difference among the louse development stages ( independent of louse intensity ) and an uppercase letter indicates the single difference among louse intensity for a given louse development stage . numbers within parentheses are the number of fish used ( reading left to right ) for control , 1 louse , 2 and 3 lice per fish , respectively . values are mean ± standard error of the mean ( s . e . m . ) . ( from nendick et al . [ 13 ] ) .
however , recent work focusing on a single pink salmon stock complex concluded that salmon farms do not affect the productivity of wild salmon ( 15 ) . the study further advised against management and policy such as coordinated fallowing or closed containment technology that could reduce disease risk for wild salmon ( 15 ) . these conclusions and policy recommendations are based on a statistically nonsignificant result of a correlation test between pink salmon spawner–recruit data and l . salmonis abundance on salmon farms in the broughton archipelago . here , we reanalyze the data in ref . 15 , using a multistock model that assimilates data over broader temporal and spatial scales , and arrive at the opposite conclusion : local declines in pink salmon , as well as coho salmon , are correlated with l . salmonis abundance on salmon farms , consistent with previous work ( 11 , 12 ) .
. here we prove that the accepted life cycle of the salmon louse is wrong . by observations of chalimus larvae molting in incubators and by morphometric cluster analysis , we show that there are only two chalimus instars : chalimus 1 ( comprising the former chalimus i and ii stages which are not separated by a molt ) and chalimus 2 ( the former chalimus iii and iv stages which are not separated by a molt ) . consequently the salmon louse life cycle has only six post - nauplius instars , as in other genera of caligid sea lice and copepods in general . these findings are of fundamental importance in experimental studies as well as for interpretation of salmon louse biology and for control and management of this economically important parasite .
] , but currently there is no detailed description of the development of salmon louse after the final molt . our preliminary observations on t1 and t6 lice indicate clear differences in cuticula structure , particularly on the genital segment and abdomen . immature adult
pathogens are growing threats to wildlife . the rapid growth of marine salmon farms over the past two decades has increased host abundance for pathogenic sea lice in coastal waters , and wild juvenile salmon swimming past farms are frequently infected with lice . here we report the first investigation of the potential role of salmon farms in transmitting sea lice to juvenile sockeye salmon ( oncorhynchus nerka ) .
salmon louse is a parasite naturally occurring in norwegian waters , but due to high host density in the aquaculture industry , concentrations of the parasite can be extremely high in the vicinity of fish farms . it is therefore important to find out how to hinder parasitic infections spreading from the farms to wild fish . two genders are involved in the reproduction cycle of the salmon louse and a male and female must therefore be present on the host fish in order for the parasite to reproduce . when louse density is low , the chance of adult male and female lice meeting is less and this naturally reduces their rate of reproduction and thereby also the infection pressure . stormoen used a mathematic model to predict how high a proportion of the lice propagated in relation to different densities in the louse population .
the salmon louse is characterized by four main body parts . after the final molt into adult females , the genital segment and the posterior abdomen showed a substantial growth , whereas the large anterior cephalothorax and the small free thoracic segment remained constant ( figure
there is a significant knowledge gap regarding the response of the salmon louse during feeding . to this end , we applied a transcriptomic approach to assess the effect of host resistance on louse feeding responses . we hypothesized that the transcriptomic feeding response on more susceptible species ( atlantic , sockeye salmon ) would be enhanced in virulence factors and fitness - related pathways ( e . g . feeding , reproduction , energy metabolism ) relative to that elicited by a resistant species ( coho salmon ) . however , our results indicate a specific enhanced response to atlantic salmon that was not explained by host acclimation but that may be due to differences in co - evolutionary history of the parasite and the hosts .
a wee salmon from the eany beg and a lassoed sea trout , co . donegal , ireland
and the subsequent one obtained from atlantic salmon tissues . the new sequence , compiled from four infected
we assessed and compared the transcriptomic feeding response of the pacific salmon louse ( l . salmonis oncorhynchi , ) while parasitizing the highly susceptible atlantic salmon and sockeye salmon ( oncorhynchus nerka ) or the more resistant coho salmon ( oncorhynchus kisutch ) using a 38 k oligonucleotide microarray . the response of the louse was enhanced both in the number of overexpressed genes and in the magnitude of expression while feeding on the non - native atlantic salmon , compared to either coho or sockeye salmon . for example , putative virulence factors ( e . g . , cathepsin l , trypsin , carboxypeptidase b ) , metabolic enzymes ( e . g . , cytochrome b , cytochrome c ) , protein synthesis enzymes ( e . g . , ribosomal protein p2 , 60s ribosomal protein l7 ) , and reproduction - related genes ( e . g . , estrogen sulfotransferase ) were overexpressed in atlantic - fed lice , indicating heightened parasite fitness with this host species . in contrast , responses in coho - or sockeye - fed lice were more similar to those of parasites deprived of a host . to test for host acclimation by the parasite , we performed a reciprocal host transfer experiment and determined that the exaggerated response to atlantic salmon was independent of the initial host species , confirming our conclusion that the pacific salmon louse exhibits an enhanced response to atlantic salmon .
] . for pre - ad ii lice this could be related to the fact that the louse is attached to the salmon host through a frontal filament during molting . however , this is somewhat contradicted by the fact that the pre - ad ii transcribed
eichner c , nilsen f , grotmol s , dalvin s . a method for stable gene knock - down by rna interference in larvae of the salmon louse ( lepeophtheirus salmonis ) . experimental parasitology . 2014 ; 140 : 44–51 . pmid : 24632188 .
despite the lack of information on the direct effect of salmon lice on juvenile pink salmon , a model was developed that predicted imminent collapse of wild pink populations in the region owing to louse - induced mortality [ 16 ] . this model and output were challenged [ 14 , 17 ] and the challenge rebutted [ 15 ] , but the populations did not collapse suggesting something had changed and / or certain assumptions were invalid . more recently , marty et al . [ 9 ] analysed 10–20 years of fish farm data and 60 years of pink salmon data and concluded that wild salmon productivity is not associated with fish farm production or farm louse numbers . further analysis of the same dataset but using a different model yielded the opposite conclusion [ 42 ] . clearly , implying cause - and - effect from indirect associations is always problematic especially when inherently limited by a vast number of assumptions required to model such a complex system . while salmon louse infection remains a possibility for low pink salmon returns , it is only one factor that may be affecting pink salmon stocks . reducing the number of assumptions is critical to moving forward in understanding this complex system .
one of the reasons why these studies were initiated was that the salmon louse appeared to have an unusually large number of larval stages compared to related animals . originally , salmon louse was described to have nine larval stages , but this new study shows that in fact , it only has seven . - the two stages that have “disappeared” are chalimus stages , where the louse is attached to the host fish by a filament . these stages are difficult to follow since they are small and sitting on the fish . this is one of the reasons why the number of stages was determined wrongly . also , this new study has revealed that chalimus larvae grow in size between the molt events . normally , animal with an exoskeleton need to molt to expand in size , the researchers involved in the study says . according to them , it has now been established that the salmon louse chalimus larvae also expand in size between molts .
concerns regarding the impacts of net - pen aquaculture on the environment are also global , particularly the potential effects on local wild fish stocks of pathogens and parasites that have been incubated inadvertently on cultured fish [ 4 ] . for example , aquaculture has been implicated in salmon louse infections of sympatric wild salmon runs in norway [ 5 ] , scotland [ 6 ] , ireland [ 7 ] and canada [ 8 ] . indeed , some but not all [ 9 ] studies have found a negative correlation between the presence of net - pen aquaculture and local wild salmon population size . correlational studies , however , lack a direct linkage between salmon louse production and wild salmon populations , while empirical data for the large number of variables that span the time between the generation of salmon lice on farmed fish and the collapse of a wild salmon population are largely lacking for modelling purposes [ 10 ] . thus , until empirical data are generated , uncertainty will remain regarding the direct impact of aquaculture on wild fish populations .
salmon is the biggest - selling seafood in the uk . most uk production is carried out by six norwegian companies . there are about 250 salmon farms off the west coast of scotland and its islands
infection with the sea louse c . rogercresseyi , as a secondary pathogen , reduces the resistance of atlantic salmon to the pathogen p . salmonis . resistance to coinfection of piscirickettsia salmonis and caligus rogercresseyi in atlantic salmon is a heritable trait . the absence of a genetic correlation between the resistance to single infection and that to coinfection indicates that different genes control these processes . further studies are necessary to investigate the effects of coinfection when the sea louse is the primary pathogen . it is clear that coinfection of different pathogens and resistance to coinfection needs to be considered in future research on salmon farming , selective breeding and conservation .
the majority of canada ' s wild salmon and salmon aquaculture occur in british columbia ( bc ) . both wild and farmed salmon contribute substantially to the economy of canada . the commercial wild pacific salmon fishery is valued annually at $ 85–250 million ( 1990–1995 , anon 2002 ) , and the recreational fishery adds another $ 1 billion ( 1995 ; national survey , anon 1995 ) . salmon farming contributes nearly $ 0 . 5 billion ( in 2006 ) . this juxtaposition of wild and cultured salmon presents unique , and often conflicting , challenges in striking a responsible , sustainable balance in resource management . politically , salmon have been the focus of federal–provincial and federal–first nations conflicts , and even international dispute ( canada versus the usa ) ; salmon are cultural icons to the first nations , deeply rooted in their mythology .
kvamme bo , skern r , frost p , nilsen f . molecular characterisation of five trypsin - like peptidase transcripts from the salmon louse ( lepeophtheirus salmonis ) intestine . international journal for parasitology . 2004 ; 34 ( 7 ) : 823–32 . pmid : 15157765 .
pert cc , luntz ajm , fryer rj , o ' shea b , bricknell ir . the settlement and survival of the salmon louse , lepeophtheirus salmonis ( kroyer , 1837 ) , on atypical hosts . aquaculture . 2009 ; 288 ( 3–4 ) : 321–4 .
krkosek m , ford js , morton a , lele s , myers ra , lewis ma . declining wild salmon populations in relation to parasites from farm salmon . science . 2007 ; 318 : 1772–5 .
high salmon lice levels cause problems both for farmed and wild salmonids . photo © kari sivertsen / nina
krkosek m , ford js , morton a , lele s , myers ra , et al . ( 2007 ) declining wild salmon populations in relation to parasites from farm salmon . science 318 : 1772–1775 .
krkošek m , ford js , morton a , lele s , myers ra , et al . ( 2007 ) declining wild salmon populations in relation to parasites from farm salmon . science 318 : 1772–1775 .
atlantic salmon parr were obtained from a commercial salmonid hatchery , coho salmon parr were obtained from the chase river hatchery on vancouver island , british columbia ( b . c . ) , canada and sockeye salmon parr were obtained from the inch creek hatchery , chilliwack , b . c . , as previously described [
this close - up shows a salmon louse ( lepeophtheirus salmonis ) in the ‘chalimus’ stage which is about to shed its shell . a scientist with expertise in marine parasites thinks if a louse were to make it to the fresh fish counter in a retail market it would most likely have to be in this nearly microscopic stage . ( photo : r . skern - mauritzen and c . marlowe / institute of marine research , bergen )
kjoglum s , henryon m , assmundstad t , korsgaard i ( 2008 ) selective breeding can increase resistance of atlantic salmon to furunculosis , infectious salmon anemia and infectious pancreatic necrosis . aquac res 39 : 498–505 .
salmon farms are transferring parasitic sea lice to wild salmon over a much wider region than first thought . thats the conclusion of a newly published article called evidence of farm - induced parasite infestations on . . .
hamre la , eichner c , caipang cma , dalvin st , bron je , nilsen f , et al . the salmon louse lepeophtheirus salmonis ( copepoda : caligidae ) life cycle has only two chalimus stages . plos one . 2013 ; 8 ( 9 ) . artn e73539
) salmon . pathog : wild farmed fish sea lice . ellis horwood ; 1993 . p . 68–82 .


the wingspan is about 15 mm .

the ground colour of forewings is yellowish cream , strigulated ( finely streaked ) and reticulated ( a net-like pattern ) with brown .

the costa is suffused with brownish and the tornal and terminal areas are suffused with brownish grey .

the hindwings are creamish grey , but more cream at the costa where brownish reticulation is found .

arotrophora khasiasana

this is the place for khasiasana definition . you find here khasiasana meaning , synonyms of khasiasana and images for khasiasana copyright 2017 © urltoken
here you will find one or more explanations in english for the word khasiasana . also in the bottom left of the page several parts of wikipedia pages related to the word khasiasana and , of course , khasiasana synonyms and on the right images related to the word khasiasana .
arotrophora khasiasana is a species of moth of the tortricidae family . it is found in india , where it has been recorded from the khasi hills .
khasiasana razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 37 . tl : india , khasias hills . holotype : bmnh . male .
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tubulosa razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 49 . tl : fiji , holotype : bmnh . female .
gilligani razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 43 . tl : formosa [ taiwan ] , holotype : bmnh . female .
paiana razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 39 . tl : india , khasias hills . holotype : bmnh . male .
cherrapunji razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 41 . tl : india , assam , cherapunji . holotype : bmnh . female .
fijigena razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 43 . tl : fiji , viti levu , suva . holotype : bmnh . male .
obrimsocia razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 46 . tl : thailand , doi inthanon national park . holotype : bmnh . male .
inthanona razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 42 . tl : thailand , doi inthanon n . p . . holotype : bmnh . male .
bernardmyo razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 47 . tl : burmah [ myanmar ] , bernardmyo , ruby mines . holotype : bmnh . male .
utarana razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 48 . tl : indonesia , sulawesi utara , dumoga bone national park . holotype : bmnh . female .
diadela common , 1963 ( arotrophora ) , austral . j . zool . 11 : 103 . tl : australia , western , 8 mi nw nornalup . holotype : anic . female .
kundasanga razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 45 . tl : sabah , mt . kinabalu , nr kundasang golf course . holotype : bmnh . male .
charopa razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 44 . tl : thailand , doi inthanon n . p . , km 31 . holotype : bmnh . male .
ericirra common , 1963 ( arotrophora ) , austral . j . zool . 11 : 93 . tl : australia , new south wales , mt . victoria . holotype : anic . male .
siniocosma turner , 1926 ( arotrophora ) , trans . r . soc . s . austral . 50 : 136 . tl : australia , byfield , yeppoon . holotype : anic . female .
hongsona razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 36 . tl : thailand , mae hong son , pai district , doi mae ya . holotype : bmnh . male .
charistis meyrick , 1910 ( arotrophora ) , proc . linn . soc . n . s . w . 35 : 261 . tl : australia , queensland , cooktown . lectotype : bmnh . male .
charassapex razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 39 . tl : thailand , chiang mai , chiang dao , san pakia rfd , watershed station . holotype : bmnh . female .
khatana razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 38 . tl : thailand , chiang mai , doi chiang dao , den yaa kat , subst . holotype : bmnh . male .
canthelias meyrick , 1910 ( arotrophora ) , proc . linn . soc . n . s . w . 35 : 263 . tl : australia , new south wales , mittagong . holotype : bmnh . female .
salebrata meyrick , 1910 ( arotrophora ) , proc . linn . soc . n . s . w . 35 : 265 . tl : australia . victoria , gisbourne . syntype ( s ) : bmnh . 1 female .
khunmaei razowski , 2009 ( arotrophora ) , polskie pismo entomol . 78 : 40 . tl : thailand , chiang mai , doi chiang dao ws , highway 1322 to wiang haeng , 3 km from khun mae ngaai c ' point . holotype : bmnh . female .
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anemarcha lower , 1902 ( tortrix ) , trans . r . soc . s . austral . 26 : 236 . tl : australia , new south wales , sydney . holotype : sama . female .
arcuatalis walker , 1865 ( scopula ) , list specimens lepid . insects colln . br . mus . 34 : 1474 . tl : australia , new south wales , sydney . lectotype : bmnh . male .
submarginellus walker , 1866 ( crambus ) , list specimens lepid . insects colln . br . mus . 35 ( suppl . ) : 1760 . tl : australia . holotype : bmnh . female .
transcissella walker , 1866 ( eromene ) , list specimens lepid . insects colln . br . mus . 35 : 1762 . tl : australia . new south wales , sydney . holotype : bmnh . male .
euides turner , 1927 ( tortrix ) , pap . r . soc . tasmania 1926 : 127 . tl : australia , tasmania , mt . wellington , springs . holotype : anic . male .
ochraceellus walker , 1863 ( crambus ) , list specimens lepid . insects colln . br . mus 28 : 177 . tl : australia , damel . lectotype : bmnh . female .
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lepidochrysops victoriae , the victoria blue or lake victoria giant cupid , is a butterfly in the lycaenidae family .

it is found in burkina faso , ghana , togo , benin , nigeria , cameroon , the democratic republic of the congo , sudan , uganda and kenya .

the habitat consists of savanna .

lepidochrysops victoriae

lepidochrysops is a genus of butterfly in the lycaenidae family . the members ( species ) are found in the afrotropical ecozone .
libert , m . 2001 euchrysops butler et lepidochrysops hedicke : deux genres distincts ? description de quatre nouvelles especes et de deux nouvelles sous - especes ( lepidoptera , lycaenidae ) . lambillionea 101 , 351 - 371 .
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to cite this page : myers , p . , r . espinosa , c . s . parr , t . jones , g . s . hammond , and t . a . dewey . 2018 . the animal diversity web ( online ) . accessed at https : / / animaldiversity . org .
disclaimer : the animal diversity web is an educational resource written largely by and for college students . adw doesn ' t cover all species in the world , nor does it include all the latest scientific information about organisms we describe . though we edit our accounts for accuracy , we cannot guarantee all information in those accounts . while adw staff and contributors provide references to books and websites that we believe are reputable , we cannot necessarily endorse the contents of references beyond our control .
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an extremely diverse african genus . most of the species are endemic to the cape region of south africa . larvae feed on lamiaceae and verbenaceae in early instars , and then are taken into ant nests , where they are tended by the ants , consuming ant larvae and pupae , until they pupate ( larsen 2005 ) .
ackery , p . r . , smith , c . r . & vane - wright , r . i . ( ed . ) 1995 carcasson ' s african butterflies . canberra : csiro .
larsen , t . b . 2005 butterflies of west africa . stenstrup , denmark : apollo books .
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curators : konstantin efetov , vasiliy feoktistov , svyatoslav knyazev , evgeny komarov , stan korb , alexander zhakov .
species catalog enables to sort by characteristics such as expansion , flight time , etc . .


solanderia ericopsis is a hydroid in the family solanderiidae , the group commonly known as tree hydroids or sea fan hydroids .

s. ericopsis forms very large , conspicuous colonies from 5 to 50 cm in height , which are often noted by divers .

they are usually strictly fan-shaped but can sometimes be bushy .

the colonies can be unusually long-lived : during long-term monitoring of defined rock areas around the poor knights islands , one researcher observed a single colony of s. ericopsis over fifteen years , during which it reached 50 cm in height .

solanderia ericopsis

a commonly found new zealand species is solanderia ericopsis ( carter , 1873 ) , which is found all around the country at depths ranging from 2 to 200 metres .
i also wish to thank the director of the australian museum , sydney , n . s . w . , for access to material of chitina . ericopsis and solanderia fusca .
chitina ericopsis carter , 1873 ( a
doubtful
genus according to vervoort , distribution new zealand ) .
no one has contributed data records for solanderia yet . learn how to contribute .
taxonomic drawings of solanderia ericopsis , including the colony ( a ) , and a close up view of a branch showing polyps and the gonophores ( b ) . [ image from schuchert , 1996 , fig . 84 , page 140 ]
solanderia leuckarti marshall , 1892 ( described as a
doubtful
species by vervoort , distribution unknown , but probably the pacific ) .
in situ photograph of a species of solanderia taken by niwa diver crispin middleton at the poor knights islands . [ crispin middleton , niwa ]
solanderia duchassaing & michelin , 1846 , which is commonly known as the tree hydroid or sea fan hydroid , is a genus of athecate hydrozoan .
five infertile colonies , 4 - 12 cm tall , of the gymnoblastic hydroid , solanderia misakinensis ( inaba , 1892 ) , from auckland harbour , and two infertile colonies from wellington harbour , one 30 cm tall and the other 6 cm tall , are described . comparison of growth features between the auckland and wellington specimens determines the auckland specimens as young colonies . the relationships of s . misakinensis to other species of the genus , in particular those recorded from new zealand and australia , are reviewed . chitina ericopsis carter , 1873 is almost certainly conspecific with the present material . a specimen of solanderia fusca ( gray , 1868 ) collected by pennycuik is probably the species solanderia secunda ( inaba , 1892 ) .
the status of the new zealand species of the family solanderiidae is discussed , and material from auckland and wellington harbour is recognized as solanderia misakinensis ( inaba , 1892 ) .
a portion of a branch of chitina ericopsis ( dried material only ) cannot be distinguished in structure from that seen in a branch of equivalent dimensions of the present material . chitina may therefore be inseparable from solanderia , as vervoort suggests ( 1962 , p . 537 ) . however as no description of soft parts of chitina exists , it is difficult to see how any living or well - preserved specimen can ever be assigned to this genus .
the histology of a species of solanderia duchassaing & michelin , 1846 from auckland harbour , new zealand , with special reference to the internal skeleton of the solanderiidae ( coelenterata , hydrozoa ) .
close up photograph of the terminal branches of a species of solanderia . if you look closely you can see small round light orange balls which are its reproductive structures . [ crispin middleton , niwa ]
schuchert , p . ( 2013 ) . solanderia duchassaing & michelin , 1846 . in : schuchert , p . ( 2015 ) world hydrozoa database . accessed at urltoken on 2016 - 04 - 20
in situ photograph of a species of solanderia at houhora harbour channel rock , northland . [ mike page , niwa . photo from the terramarine pharmaceuticals ( tmp ) marine natural products ( mnp ) photo collection ]
it is often noticed and photographed by divers around new zealand because of its beautiful shape , large size , and the colour of its colony . solanderia is the only genus from the family solanderiidae , and includes seven species .
in situ photograph of a species of solanderia at rakitu island ( arid island ) , great barrier island . [ mike page , niwa . photo from the terramarine pharmaceuticals ( tmp ) marine natural products ( mnp ) photo collection ]
the material on which this study is based is a collection of five colonies preserved in formalin , from 4 to 12 cms high , taken from auckland harbour , n . z . , and two colonies , one 30 cms high and one 6 sms high , taken from wellington harbour , n . z . specimens of solanderia fusca ( gray , 1868 ) from new south wales and queensland , australia , and a specimen of chitina ericopsis carter , 1873 were studied to aid in identifying the auckland and wellington harbour species which unfortunately were devoid of reproductive organs , so that descriptions of these organs were not made .
underwater photography of jason mirabilis nudibranch by new zealand photojournalist and underwater photographer richard robinson . jason mirabilis order : nudibranchia suborder : aeolidina family : glaucidae distribution : three kings to fiordland occurrence : common size : up to 65mm food : solanderia hydroid .
( of chitina ericopsis carter , 1873 ) carter h . j . 1873 . transformation of an entire shell into chitinous structure by the polype hydractinia , with short descriptions of the polypidoms of five other species . annals and magazine of natural history ( 4 ) 11 : 1 - 15 , plate 1 . , available online at urltoken page ( s ) : 13 [ details ]
the solanderia hydroid belongs to the order anthoathecata ( comprising of around 1000 species ) , known as athecate hydroids . athecate hydroids do not have a skeletal covering for their polyps , as opposed to the thecate hydroids ( order leptothecata ) , which do . some species of athecate hydroid are only known from their medusa stage or their polyp stage , or both . solanderia known from its polyp , or hydroid stage , is colonial , and produces gonophores ( containers holding sexual products ) which release sperm and eggs for reproduction .
in the course of identifying the present material two specimens labelled as solanderia fusca ( gray , 1868 ) were studied . one was collected in sydney , australia , ( australian museum , no . y . 509 ) and the other from queensland , collected by dr . pamela pennycuik . the specimen from sydney is undoubtedly s . fusca and agrees in every detail of skeletal structure with the specimen ceratella fusca gray , 1868 described by spencer ( 1891 ) . the specimen from queensland , however , is certainly not s . fusca . the skeleton is very similar to that of solanderia secunda ( inaba , 1892 ) with a flattened , thorn shaped projection either side of the polyp base and no hydrophore as in s . fusca . the colour of the queensland specimen is dark brown as in s . secunda , and the method of branching is similar . as the distribution of s . secunda is tropical and subtropical regions of the pacific ocean ( vervoort , 1962 ) it seems very likely that the queensland specimen is in fact s . secunda .
critter of the week : the brightly coloured and aptly named clown nudibranch , ceratosoma amoenum .
critter of the week : the king of the ocean , the king crab lithodes aotearoa .
this week ' s critter is the sand - dollar associate oxydromus sp . , a hesionid polychaete .
class hydrozoa is part of the phylum cnidaria , which means they are related to corals and anemones ( order anthozoa ) , and jellyfish ( order scyphozoa ) . surprising to some , hydrozoa is the most diverse group of cnidarians , comprising of about 3500 species . the freshwater genus hydra is probably the most well - known hydrozoan , but there are many other forms of hydroid and the majority are actually marine animals .
hydroids are remarkably varied and some are known only by certain life stages . they have polyps which are found usually on the end of stems or along branches , and live together either as a colony or solitary . some species produce a jelly - like swimming medusa ( which are often confused with jellyfish ) as a form of reproduction .
hydroids share a known characteristic of cnidarian animals – they sting ! hydroids have a stinging capsule called a nematocyst , used to paralyse their prey . their prey , such as fish larvae and copepods , are captured by the tentacles arising from the polyp , and with help from their nematocysts , are then transferred to the mouth and stomach for digestion .
schuchert , p . ( 1996 ) . the marine fauna of new zealand : athecate hydroids and their medusae ( cnidaria , hydrozoa ) . 147 p . new zealand oceanographic institute memoir 106 .
schuchert , p . ( 2016 ) . world hydrozoa database . accessed at urltoken on 2016 - 04 - 20
vervoort , w . ; schuchert , p . & van der land , j . ( 2000 - 2007 ) . as a contribution to unesco - ioc register of marine organisms . ( look up in imis ) [ details ]
cairns , s . d . ; gershwin , l . ; brook , f . j . ; pugh , p . ; dawson , e . w . ; ocaña o . v . ; vervoort , w . ; williams , g . ; watson , j . e . ; opresko , d . m . ; schuchert , p . ; hine , p . m . ; gordon , d . p . ; campbell , h . j . ; wright , a . j . ; sánchez , j . a . ; fautin , d . g . ( 2009 ) . phylum cnidaria : corals , medusae , hydroids , myxozoans . in : gordon , d . p . ( ed . ) ( 2009 ) . new zealand inventory of biodiversity : 1 . kingdom animalia : radiata , lophotrochozoa , deuterostomia . pp . 59 - 101 . , available online at urltoken [ details ] available for editors [ request ]
schuchert , p . , 1996 . the marine fauna of new zealand : athecate hydroids and their medusae ( cnidaria : hydrozoa ) . new zeal . oceanog . inst . mem . 106 : 1 - 159 . page ( s ) : 139 , fig . 84a - g [ details ]
biology the gonophores can be released as free swimming medusoids ( unpublished observations p . schuchert ) . [ details ]
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the colonies from auckland and wellington harbours are erect and have no hydrophore or supporting structure of any kind at the base of the polyps . this eliminates them from many of the species described by vervoort ( 1962 ) , but leaves them as possible members of the following genera and species .
the colony growth form of the auckland specimens used in this study is identical with that of s . gracilis except that the polyps on the branch tips are borne in all planes , and not only in the plane of flattening of the colony . the skeleton of s . gracilis is purple coloured , but the skeletons of the auckland and wellington specimens preserved in formalin are a uniform light brown .
the present material lacks tubercles of fused fibres on fine branches such as are described for s . leuckarti .
s . misakinensis , as described by vervoort ( 1962 ) possesses a much closer , denser form of branching than the auckland specimens , but is identical to the largest ( 30 cm high ) wellington harbour colony . growing from the same tangled root - like base of the wellington material a little to the side of the large colony is a colony 6 cm high , and this smaller one has the same growth pattern as the auckland harbour specimens . there is little doubt that the auckland and wellington specimens are members of the species s . misakinensis , and that the auckland material is at an earlier stage of development than that which is figured and described by vervoort .
a histological study of the auckland harbour material confirms vervoort ' s findings ( 1966 ) that the chitinous skeleton is ectodermal in origin . the pattern of growth , and the formation of the skeleton is described for a branch tip of a colony .
described from the skeleton by carter in 1873 . the collection locality is stated simply as new zealand . the skeletons of several colonies were dredged from soft mud in wellington harbour some ten years ago , but the first colonies from new zealand waters with identifiable soft parts
are those described here from auckland , collected in 1960 . this year ( 1967 ) the largest complete new zealand colony was dredged from bottom mud at 8 fathoms in wellington harbour .
early systematic studies were based mainly on the growth form of the colonies and on the structure of the skeleton , in particular the structure of the hydrophore or
supporting cup
which is found at the base of polyps in certain species .
several tips of branches about 1 cm long were stained in delafield ' s haematoxylin and embedded in wax . some of these blocks were cut to give transverse serial sections from the stem tip , and others were cut to give longitudinal serial sections . the sections were placed on slides in series , over - stained in delafield ' s haematoxylin and differentiated in acid alcohol , countersigned in eosin ( 0 . 5 % soln . in 90 % alcohol ) and mounted in dpx mountant . most sections were cut at 10μ on a rocker microtome , but one transverse series was cut at 5μ . a thicker piece of stem ( 1cm × . 5mm × . 4mm ) was embedded , cut in transverse section at 10μ and stained and mounted as above .
in addition , a 1cm length of stem from the tip of a branch was denuded of soft tissues by dipping into
janola
( a commercial solution of sodium hypochlorite ) , and the remaining skeleton was washed and stained in a 0 . 5 % soln . of lignin pink in cellosolve for 48 hours . after this time the skeleton was mounted in dpx for observation . three lengths of stem from the tip to the thicker parts of the branch were also rid of soft tissues by the same method and were stained in the lignin pink soln . for ½ hour . after this time they were removed to absolute alcohol .
from one series of transverse sections of a branch tip , a model of the soft parts ( endoderm only ) was constructed to illustrate the method of branching of coenosarc tubes within a branch tip . ( it was assumed that the growth pattern in a branch tip is indicative of the growth pattern of the colony as a whole ) .
the colony is erect , arising from a flattened , root - like base from which is formed a strong stem . this stem branches irregularly forming large and small branches which , near the base of a colony , have the appearance of being formed of intertwined branches , and which may anastomose if they come into contact . branching in small colonies ( 4 - 12cms high ) is in one plane only , so that the colony has a flattened , fan - shaped appearance . larger colonies have a more bushy appearance . the colour of the colony skeleton is an overall brown , but is paler on the small branch tips . the polyps ( white in preservative ) are borne on all branches , but do not arise directly from the tip of any of the branches . they are elongate ( up to 2½ mm in length in the preserved state ) naked cylindrical structures with a conical hypostome . the base of the polyp is without hydrophore or supporting bract of any kind . tentacles are given off throughout the length of the polyp and normally appear irregularly placed , but in a well extended polyp are seen to be arranged in a spiral at intervals along the polyp , except for an oral whorl of four tentacles .
fig . 1 the colony x 3 / 5 . fan shaped , and flattened in the plane of branching .
fig . 2 longitudinal section of a polyp to show 3 distinct regions : hypostome ; glandular region ; region of large endodermal cells .
fig . 4 the skeleton of a branch tip . flattened , longitudinal fibres are joined by struts ( transverse fibres ) .
co , coelenteron ; ect , ectoderm ; end , endoderm ; gl , gland - cell region ; hyp , hpostome ; long fib , longitudinal fibre ; trans fib , transverse fibre ; t , tentacle .
fig . 1 the glandular region of a polyp . cells packed with acidophil globules line the gastric cavity .
fig . 2 longitudinal section of a tentacle . it is capitate , and solid .
figs . 3 , 4 cross section through a stem at a polyp base . the sections are 10μ apart . no skeletal supporting cup or hydrophore is present . the skeleton is lined with
inner
ectoderm which is continuous with the
outer
ectoderm . co , coelenteron ; ect , ectoderm ; ect ' ,
outer
ectoderm ; ect
,
inner
ectoderm ; end , endoderm ; gl , gland cells ; mes , mesoglea ; n , nematocysts ; sk , skeleton .
internal structure : the polyp ( plate i , figs . 2 , 3 ; plate 2 , figs . 1 , 2 ) .
in longitudinal section ( plate 1 , fig . 2 ) the polyp has three distinct regions , namely ( a ) —the hypostome , in which the main feature is the very strongly developed endothelial muscular cells ; ( b ) —a secretory region of from ⅓ to ⅔ the length of the polyp consisting of many cells opening into the coelenteron and its branches [ these cells are packed with acidophilic globules ( plate 2 , fig . 1 ) ] ; and ( c ) —at the base of the polyp there is a region of large vacuolated endodermal cells which extends for approximately a third of its length . the nuclei and cytoplasm of these cells are distally placed , and each cell usually subtends , at its base , two or three ectodermal cells .
the ectoderm of the polyp is somewhat cuboidal and is continuous with that over the surface of the whole colony . in extended polyps it is drawn out into a very thin layer ( plate 1 ) .
the mesoglea is prominent in retracted zooids , but is thin when the zooids are extended . it is light staining , and appears structureless . in retracted polyps a very large number of cut ends of myonemes from the ectodermal cells are seen embedded in the mesoglea , and myonemes can be seen in the ectodermal cells .
the tentacles have a solid core of vacuolated endodermal cells and are capitate . batteries of nematocysts occur in their swollen
cap - like
distal ends ( plate 2 , fig . 2 ) . nematocysts are sometimes seen in the ectoderm towards the base of a polyp , but apart from this are confined to the tentacles . only stenoteles ( penetrating nematocysts ) have been seen , and they are usually about 5μ long , but often may be as large as 10μ long .
the branch tip ( plate 3 , figs . 1 , 2 , 3 , 4 ) .
thicker branches of the colony give the appearance of being formed of intertwined smaller branches . the very tips of branches , although of small diameter show a similar structure when seen in transverse section .
in plate 3 , figs . 1 and 3 are transverse sections through a typical branch tip and are 10μ apart . the stem or branch tip is seen to be composed of several coenosarc tubes . there is a central tube ( that is endoderm , mesoglea , and ectoderm ) and radially - placed coenosarc tubes .
between these tubes are the skeletal elements . the skeleton is not formed around the whole circumference of the stem , but only between the inner ectoderm layer of adjacent coenosarc tubes ( plate 2 ) . the whole stem is covered with a columnar epithelium .
the
inward facing
layer of the ectoderm of the outer coenosarc tubes , and the ectoderm of the central coenosarc tube are composed of vacuolate cells with the cytoplasm and nucleus distally placed . these ectodermal cells are clearly delimited from the endoderm of the tubes by a thin layer of structureless , lightly staining mesoglea . small eosinophil particles are frequently present in the ectodermal cells , especially those cells which abut against the skeleton . the coelenteron of the coenosarc tubes appears as narrow branching channels ( plate 2 ) . gland cells packed with large eosinophil globules are seen in the endoderm of the tubes , especially in thicker stems , even though the coelenteron cannot be seen . in some transverse sections of a branch tip the coelenteron can be followed through the polyp to the endoderm of a coenosarc tube , but in the latter the coelenteron is not prominent . the
closing - over
of the coelenteron in the coenosarc tubes is probably due to contraction during preservation .
fig . 1 cross section through a branch tip . note the columnar ectoderm enclosing skeletal elements and endoderm . the regular arrangement of coenosarc tubes , and therefore of skeletal elements , is clearly seen .
fig . 2 an enlarged portion of fig . 1 . secretory ectodermal cells are seen at the junction of 3 ribs of skeleton .
fig . 3 cross section of a branch tip 10μ from fig . 1 .
fig . 4 the area of fig . 3 corresponding to the area shown in fig . 2 . the skeletal structures are reduced , but in their place are secretory ectoderm cells which show a granular cytoplasm .
ect , ectoderm ; end , endoderm ; p , polyp base ; sec ect , secretory ectoderm ; sk , skeleton .
the ectodermal and endodermal cells are markedly different . endodermal cells take stain more readily than do ectodermal cells ; they also differ in the characteristics of their nuclei . both the outer columnar and the inner secretory ectoderm cells have round nuclei of about 3μ . diameter , while endodermal nuclei may be up to 6μ diameter and are often irregular in outline . the nucleus of the ectodermal cells (
) has a purplish staining nucleolus which is surrounded by about six small , darkly staining , chromatin bodies . from each of these small chromatin bodies there is a fine darkly staining radial process which connects with a small peripheral body . the nucleoplasm is irregularly granular . the nucleus of the endodermal cells (
) has a nucleolus which stains a brighter red , and fewer darkly staining bodies . but these bodies are larger than in the ectodermal cell nucleus , and are found irregularly scattered throughout the nucleoplasm . the nucleoplasm of the endodermal cell nucleus is much less granular than that of the ectodermal cell nucleus .
bipolar and multipolar nerve cells occur between endoderm and ectoderm of the coenosarc tubes . the nucleus of these cells occupies the greater part of the cell body and stains very darkly . the cytoplasm is also deeply stained , and is agranular .
although the outer ectoderm appears to be free of nematocysts , except at the base of a polyp , nematocysts occur in the internal etcoderm . in the latter cell layer , they total about 40 % of the ectodermal cell number in thicker branches ( plate 2 , figs . 3 and 4 ) . both large ( 10μ ) and small ( 5μ ) stenoteles are present , and many stages of development can be seen .
typical endodermal and secretory ectodermal cells . a , endodermal cells . the cytoplasm contains large acidophil globules . the nucleus has a nucleolus and irregularly placed chromatin bodies . b , secretory ectodermal cells . the cytoplasm is vacuolated . fine chromatin strands radiate from the nucleolus to peripheral chromatin bodies in the nucleus .
chr , chromatin body ; cy , cytoplasm ; gl , globules ; n , nucleus ; nuc , nucleolus ; st , chromatin strand .
the skeleton ( plate 1 , fig . 4 ; plate 2 , fig . 3 ) .
the skeleton of a branch tip is a network of
chitinous
fibres ( plate 1 , fig . 4 ) . there are major fibres running longitudinally which curve to meet at the tip of the branch . these main fibres are joined by struts which are flattened in the direction of the branch and which occur about 0 . 09 mm apart . combining the information given in the accompanying plates , the skeleton of a branch tip can be described as a network cylinder surrounding the central coenosarc tube , with radially arranged , longitudinal strips of chitinous material which are flattened laterally , and joined to the central cylinder at intervals by transverse struts . these separate the peripheral coenosarc tubes from each other . in a well preserved specimen the whole skeleton is enclosed by soft tissue .
the skeletal fibres are of lamellar construction ( plate 2 , fig . 3 ) . a branch tip skeleton had to be left in a 0 . 5 % solution of lignin pink for 48 hours before it stained evenly throughout its length . in three pieces of skeleton taken in series from a branch tip , the colour deepened greatly away from the tip of the branch when they were all stained for ½ hour . the tip stained very faintly , while the furthermost piece stained deeply .
the fact that the skeleton of the solanderiidae is internal and is completely covered by a layer of epithelial cells in the living animal has undoubtedly led to the earlier belief that the skeleton is mesogleal in origin . however , it is evident from this study that each branch of a colony is composed of several coenosarc tubes . the appearance given in cross sections of a branch tip ( pl . 3 , figs . 1 and 3 ) is very similar to that of a cable containing many wires , cut in cross section . each of the coenosarc tubes consists of endoderm , mesoglea , and ectoderm , and therefore could be expected to be capable of producing a perisarc , just as are other skelton - bearing hydroids .
the outer epithelium of the colony probably is formed by fusion of the superficial layer of the ectoderm of the peripheral coenosarc tubes in each branch . this idea is given weight by the fact that the outer epithelium can be seen to be continuous with
inner
ectoderm of the coenosarc tubes , especially at polyp bases ( pl . 2 , figs . 3 and 4 ) .
the
inward facing
ectoderm of peripheral coenosarc tubes and the ectoderm of the other coenosarc tubes contained in a stem apparently become modified into a secretory tissue which forms the skeletal fibres . skeletal material is secreted only where the ectoderm of two or more coenosarc tubes make contact . the skeleton is thus a
perisarc
contributed to by two or more coenosarc tubes . the cross sections shown in plate 3 support this interpretation , and there is no doubt that the skeleton is ectodermal in origin . the skeleton may differ in composition in young and older parts of the stem . lignin pink , which is considered a specific stain for chitin , does not stain the skeleton of branch tips as readily as it does the skeleton from thicker parts of the stem .
the method of growth of the colony can be seen from serial sections of a branch tip . from the tip to the thicker parts of a branch there is a central coenosarc tube , with peripheral tubes which anastomise with the central tube and with each other ( but the central tube anastomoses far more frequently with the peripheral tubes than do the latter with each other ) . the polyps communicate with more than one coenosarc tube at their base ( plate 3 , fig . 1 ) , and this base may be very large and extend over two or more skeletal
holes
. ( plate 2 , figs . 3 and 4 ) .
a serial reconstruction of the soft parts ( endoderm only ) ( text fig . 2 ) shows these and other features of a stem tip . the central coenosarc tube has no terminal polyp . some peripheral tubes may have a terminal polyp , but others do not . this type of anastomosing of coenosarc tubes is intermediate between that described for clathrozoon wilsoni and plumularia procumbens by spencer in 1890 , although there are fewer tubes in any one branch tip .
the skeleton shown in text fig . 2 was not reconstructed from serial sections . skeletal rods were drawn between the peripheral endoderm tubes and then joined through the holes between the anastomosing tubes . this showed a skeleton of a branch tip similar to that described from serial cross sections as illustrated in plate 3 .
the stem is clearly a fasicled or bundled structure . but the status of each of the elements composing it is more difficult to define . the alternative possibilities are firstly , that the central coenosarc tube is equivalent to a hydrocaulus and is surrounded by its branches and stolons , which anastomose with it and with each other , and secondly , that the whole stem is a rhizocaulome , being composed of upright , branching and joining stolons .
two features indicate that the first alternative is the more likely because ( a ) the stem tip clearly has a central coenosarc tube , and ( b ) the fact that this central tube anastomoses much more frequently with the peripheral tubes than the peripheral ones do with themselves . this suggests that the central tube is a primary structure , and the others are secondary to it .
the method of growth seems to be
secondary monopodial
( hyman 1940 , p . 406 ) in which the hydrocaulus and branches end in non - polyp bearing growing points . the growing points elongate and bud off laterally both polyps and new branches ( this method is more typical of thecate hydroid colonies ) — ( hyman 1940 , p . 405 ) . the picture is obscured somewhat , however , by the hydrorhizal elements of the stem .
diagrammatic reconstruction of the soft parts ( endoderm only ) of a branch tip from serial sections . one polyp is shown with ectoderm and tentacles . note the central and peripheral endodermal tubes anastomosing freely ; endodermal
feet
of the polyps . the skeleton ( black ) is formed by placing flattened longitudinal fibres between peripheral endodermal tubes and joining them through the holes left by anastomosing tubes .
the branches of the colony are fasicled structures consisting of a central coenosarc tube ( corresponding to a hydrocaulus ) which branches , and which anastomoses with its own branches and with hydrorhizal elements of the stem . these latter elements also branch and anastomose with each other .
the method of growth of the colony is
secondary monopodial
. that is , the hydrocaulus and its branches end in permanent growing points , and elongate by budding off polyps and other branches laterally .
i would like to acknowledge the assistance given by dr . patricia m . ralph and professor j . a . f . garrick of the zoology department , victoria university of wellington . dr . ralph suggested this study and provided specimens to make it possible , and with professor garrick offered much constructive criticism during the writing of this paper .
, e . a . , 1918 : descriptions of two new hydroids , and a revision of the hydroid fauna of lord howe island .
, j . e . , 1868 : notes on the ceratelladae , a family of keratose sponges .
, m . , 1892 : soshu , miura , misaki ni oide edaru hydroidea . ( the hydroids collected at miura and misaki in soshu ) .
, w . , 1892 : spongiologische beiträge . festschrift zur siebzigsten wiederkehr des geburtstages von rudolf leuckart . leipzig , pp . 1 - 336 .
, w . j . , 1957 : evolutionary trends in the classification of capitate hydroids and medusae .
duchassaing and michelin 1846 and general notes on the family solanderiidae ( coelenterata : hydrozoa ) .
— , 1966 : skeletal structure in the solanderiidae and its bearing on hydroid classification . in the cnidaria and their evolution . edited by w . j . rees . academic press .
colonies arborescently branched in one plane , several main branches arising from a thick , short trunk ; trunk of largest colony 4 mm thick near base ; in older colonies many orders of branching , the branches thinning to growing tips . skeletal meshwork on younger branches penetrated by lines of oval to quadrangular perforations aligned parallel to axis of branch , this pattern often obscured in older branches and stem .
mean of 50 hydranths per cm along length of branch ; in life , hydranths large , cylindrical , supported on prominent bicuspid skeletal spines ; all tentacles capitate , four oral and 15 - 20 others scattered over body .
gonophores male , eumedusoid , large , globular , with four radial canals ( not visible in preserved material ) and a small raised apical cap ; peduncle very short ; no nematocysts .
i ) large stenoteles , capsule subspherical , 17 - 17 . 5 x 13 - 14 µm , shaft 25 µm long with several long spines , tubule thick ; moderately abundant .
ii ) smaller stenoteles , capsule ovoid , 8 . 5 - 9 x 6 . 5 - 7 µm shaft ( partially discharged ) about same length as capsule ; tubule not seen ; abundant .
iii ) ? isorhizas , capsule subspherical , i 0 x 9 µm , tubule 25 µm ( partially discharged ) finely spinous ; rare in some hydranths , absent from others .
colour : colonies black in situ , under stereo - microscope deep purple , fading to mauve on tips of branches –or - brown , fading to yellowish on tips of branches . hydranths white , gonophores scarlet ( leaching to white in alcohol ) , radial canals white .