clubiona rosserae , or rosser 's sac spider , is a rare species of sac spider native to wetlands of great britain .

though once feared to be extinct , a colony was discovered in 2010 at chippenham fen in cambridgeshire .

it can also be found at the cavenham-icklingham heaths site of special scientific interest ( sssi ) in north suffolk .

clubiona rosserae

there you are ! a rosser ' s sac spider ( clubiona rosserae ) seen for the first time in 10 years .
rosser ' s sac - spider ( clubiona rosserae ) has historically been known from only 2 sites in the uk , both in the cambridgeshire fens . however its current population size in the uk is unknown . it is listed as a priority species by the uk biodiversity action plan , and conservation action is ongoing .
rosser ' s sac spiders ( clubiona rosserae ) are elusive critters . they have been spotted in only two places in britain since their discovery in the 1950s . before the new sighting in september , and the colony discovery in mid - october , these spiders have been overlooked since 2000 . the first photographs of live rosser ' s sac spiders , both a male with large palps a pair of short limbs in front of the legs , used during sexual intercourse in adult spiders and a female , were taken by peter harvey , who took part in the second survey .
a spider that was feared extinct in the uk has been photographed for the first time after a new colony of the species was found .
the rosser ' s sac spider , which had not been seen for 10 years , has been discovered at chippenham fen in cambridgeshire .
it makes its home in wetland areas and had been found only once before , at lakenheath fen in suffolk .
fears were growing that the spider had died out due to loss of habitat .
the light brown spider was first discovered in the 1950s , but the draining of the fens and changing farming practices since the world war ii had put it under threat .
spider enthusiast ian dawson spotted a rosser ' s sac spider in september at the cambridgeshire site , and a further search in october revealed 10 spiders .
he said :
i was extremely surprised to find the first one and then when we went back a month later it was great to find more of them .
if we ' ve managed to find 10 of them , i think there must be quite a sizeable population of rosser ' s at that particular site .
the first photographs of live rosser ' s sac spiders were taken by peter harvey , who took part in the second survey .
matt shardlow , chief executive of insect conservation charity buglife said :
this spider is globally endangered .
it ' s fantastic that it ' s still creeping around in the british countryside and we ' re ecstatic that people can now see what it looks like for the first time in history .
if we want future generations to be able to see the live animal , we will need to take great care of the tiny remaining fragments of wild wetlands in this country and reinstate large areas of lost fen .
mike taylor , of natural england , which manages the chippenham fen reserve , said :
rosser ' s sac spiders spend their days hidden in tubular silken retreats , often in a folded leaf , a bit like a sleeping bag .
it ' s a member of the clubionid family of spiders who like to hunt their prey rather than catch them in a web .
the foreign secretary quits , telling theresa may
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only known from two sites in britain : chippenham fen , cambridgeshire - the type locality - where it has been recorded on a number of occasions since it was first found there in 1951 ; and a single female found in a water trap at botany bay , lakenheath fen rspb reserve , suffolk in april 2000 . the record from tuddenham fen , west suffolk mapped in the provisional atlas is now known to be erroneous . in europe it is recorded from only a few countries , including the netherlands and poland .
confined to fens where it is found among cut sedge and reeds and in sedge tussocks . adults have been collected in every month between february and october , except march and august , suggesting an extended period of adult activity .
uk biodiversity action plan priority species . known from two sites , one the type locality , where it has been recorded on a number of occasions , and at the other just one specimen has been found . the population at chippenham fen appears to be established but dedicated survey work between 2002 and 2005 failed to refind it there or at lakenheath fen
chippenham fen is a national nature reserve , and lakenheath fen an rspb reserve . in its principal site at chippenham fen , water abstraction in the surrounding area is thought to have reduced water levels in the fen .
management at chippenham fen is aimed at maintaining a high ground water table and preventing carr woodland encroaching on open sedge beds by a regime of annual mowing and grazing . grazing has also been reintroduced to botany bay by the rspb , and water levels are controlled to keep the site wet . further survey work is needed to establish the continued presence of this species at these two sites , and to discover new sites , and then to carry out research on its ecology to enable best management practice to benefit the species .
text based on dawson , i . k . , harvey , p . r . , merrett , p . & russell - smith , a . r . ( in prep . ) .
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museum für naturkunde leibniz - institut für evolutions - und biodiversitätsforschung invalidenstr . 43 10115 berlin germany e - mail : fauna - eu ( at ) mfn - berlin . de website : urltoken
a rare wetland spider missing in action for 10 years and feared extinct is back .
an entire colony of the fuzzy brown spiders , called rosser ' s sac spiders , was uncovered in chippenham fen , a nature reserve in cambridgeshire , england . the discovery was announced by the conservation group buglife .
i was extremely surprised to find the first one and then when we went back a month later it was great to find more of them ,
said ian dawson , who spotted the camera - shy spider .
if we ' ve managed to find 10 of them , i think there must be quite a sizeable population of rosser ' s at that particular site .
finding these spiders is usually easy just look for the spider in the leaf sleeping bag .
rosser ' s sac spiders spend their days hidden in tubular silken retreats , often in a folded leaf , a bit like a sleeping bag ,
said mike taylor of natural england , which manages the chippenham reserve .
it ' s a member of the clubionid family of spiders who like to hunt their prey rather than catch them in a web . we were delighted that they have been spotted recently .
the rosser ' s sac spider prefers wetland areas , but its homelands have been disappearing over the years .
this spider is globally endangered ,
said matt shardlow , chief executive of buglife .
it ' s fantastic that it ' s still creeping around in the british countryside and we ' re ecstatic that people can now see what it looks like for the first time in history .
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long list of key species from the 1995 steering group report . inclusive of all species on middle and short lists . no longer in use .
taxa in danger of extinction and whose survival is unlikely if the causal factors continue operating . superseded by new iucn categories in 1994 , but still applicable to lists that have not been reviewed since 1994 .
species “of principal importance for the purpose of conserving biodiversity” covered under section 41 ( england ) of the nerc act ( 2006 ) and therefore need to be taken into consideration by a public body when performing any of its functions with a view to conserving biodiversity .
the uk list of priority species and habitats contains 1150 species and 65 habitats that have been listed as priorities for conservation action under the uk biodiversity action plan ( uk bap ) .
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national inventory of natural heritage , website : https : / / inpn . mnhn . fr .
this project will help to conserve one of the uk ' s rarest and most elusive spiders , known from only two sites in the cambridgeshire fens .
project aims to secure rosser ' s sac - spider from extinction in east anglia and the uk , and improve the management of fenland habitats for spiders in general .
what is buglife doing ? buglife is chairing the steering group and managing the field worker who is studying rosser ' s sac - spider and surveying current and potential sites . anglian water is sponsoring the work on the spider . english nature is providing additional financial support and is planning to support a university of east anglia phd student who will study spider ecology . the british arachnological society is providing volunteer specialists and spider expertise .
at the end of the project we should know exactly where the spider occurs in england , its ecological requirements and whether more action is required to prevent the species becoming extinct in the uk . in addition , we will learn more about fenland management for spiders and this will be made available to landowners .
in september 2010 ian dawson of the british arachnological society found a female in a pile of cut vegetation very close to where the species was seen in the early 1990s . this is the first record from the uk for 10 years and the first record from chippenham fen for 14 years . a buglife survey of lakenheath fen rspb reserve this year failed to relocate that population .


proserpinus vega ( vega sphinx moth ) is a moth of the family sphingidae .

it is found from southern arizona , new mexico and texas south into mexico .

the wingspan is 61 – 67 mm .

the forewing upperside is similar to proserpinus terlooii but with an additional dark green basal band .

the hindwing upperside is as in proserpinus juanita .

there is one generation per year with adults on wing in august .

the larvae feed on onagraceae species , including oenothera , gaura and epilobium species .

proserpinus vega

no one has contributed data records for proserpinus vega yet . learn how to contribute .
proserpinus vega , male , underside . united states , new mexico , 20 mi . s of mountainair
proserpinus vega , male , upperside . united states , new mexico , 20 mi . s of mountainair
proserpinus vega , female , underside . united states , texas , davis mountains , nr . fort davis
evidence of repeated and independent saltational evolution in a peculiar genus of sphinx moths ( proserpinus . sphingidae ) .
family : sphingidae , latreille , 1802 subfamily : macroglossinae , harris , 1839 tribe : macroglossini , harris , 1839 genus : proserpinus hubner , [ 1819 ] . . . . . . . . . . . species : vega dyar , 1903
additional notes on proserpinus clarkia and arctonotus lucidus ( sphingidae ) life histories from the pacific coast of n . america
transferred to arctonotus by draudt , 1931 , in seitz ( ed . ) , die gross - schmett . erde 6 : 886 ; then to proserpinus by hodges , 1971 , in dominick et al . , moths amer . n . of mexico 21 : 138 ( key ) , 141 .
( wing span : 2 3 / 8 - 2 5 / 8 inches ( 6 . 1 - 6 . 7 cm ) ) , flies in arizona , new mexico , and texas south into mexico .
the upperside of the forewing is green - gray with darker green at the base , median area , and tip . the upperside of the hindwing is red - orange with a black outer margin and a tan patch on the inner margin .
adults fly as a single brood in august . adults fly during the afternoon , nectaring from flowers .
females call in the males with a pheromone released from a gland at the tip of the abdomen .
eggs hatch about 10 days after the female deposits them on the host plant , and the newly - hatched caterpillars eat their eggshells .
forewing upperside is green - gray with darker green at the base , median area , and tip . hindwing upperside is red - orange with a black outer margin and a tan patch on the inner margin .
population status , ecological requirements , and conservation needs , if any , should be determined .
g2 - imperiled globally because of rarity ( 6 to 20 occurrences ) , or because of other factors demonstrably making it very vulnerable to extinction throughout its range . ( endangered throughout its range ) .
photographs are the copyrighted property of each photographer listed . contact individual photographers for permission to use for any purpose .
hodges , r . w . , 1971 . moths of america north of mexico , fascicle 21 : p . 141 ; pl . 13 . 7 . order
tuttle , j . p . , 2007 . hawk moths of north america : p . 191 ; pl . 3 . 19 .
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upcoming events 2018 bugguide gathering in virginia july 27 - 29 : registration and discussion photos of insects and people from the 2015 gathering in wisconsin , july 10 - 12 photos of insects and people from the 2014 gathering in virginia , june 4 - 7 . photos of insects and people from the 2013 gathering in arizona , july 25 - 28 photos of insects and people from the 2012 gathering in alabama photos of insects and people from the 2011 gathering in iowa photos from the 2010 workshop in grinnell , iowa photos from the 2009 gathering in washington
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contributors own the copyright to and are solely responsible for contributed content . click the contributor ' s name for licensing and usage information . everything else copyright © 2003 - 2018 iowa state university , unless otherwise noted .
contributed by maury j . heiman on 15 november , 2013 - 9 : 23am
contributed by maury j . heiman on 23 february , 2013 - 4 : 21pm
contributed by maury j . heiman on 10 february , 2011 - 12 : 34am
the hawk moths of north america , a natural history study of the sphingidae of the united states and canada .
this book is not out yet but pre - orders are being taken now . pre - orders here : urltoken
bombycine moths of america north of mexico , including their transformations and origin of the larval markings and armature .
packard , a . s . , 1895 . bombycine moths of america north of mexico , including their transformations and origin of the larval markings and armature . memoirs of the national academy of sciences 7 : 5 - 390 .
contributed by maury j . heiman on 11 june , 2018 - 10 : 34pm
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fj001516 genomic dna translation : aci23302 . 1 fj001517 genomic dna translation : aci23303 . 1
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tridacna squamosa , known commonly as the fluted giant clam and scaly clam , is one of a number of large clam species native to the shallow coral reefs of the south pacific and indian oceans .

it is distinguished by the large , leaf-like fluted edges on its shell called ' scutes ' and a byssal opening that is small compared to those of other members of the family tridacnidae .

normal coloration of the mantle ranges from browns and purples to greens and yellows arranged in elongated linear or spot-like patterns .

tridacna squamosa grows to 40 centimetres ( 16 in ) across .

sessile in adulthood , the clam 's mantle tissues act as a habitat for the symbiotic single-celled dinoflagellate algae ( zooxanthellae ) from which it gets a major portion of its nutrition .

by day , the clam spreads out its mantle tissue so that the algae receive the sunlight they need to photosynthesize .

fluted giant clam

fluted giant clam ( tridacna squamosa ) on sealife base : technical fact sheet .
fluted giant clam ( tridacna squamosa ) on the nparks flora and fauna website .
movement and aggregation in the fluted giant clam ( tridacna squamosa l . ) - sciencedirect
a fluted giant clam , tridacna squamosa , at omahas henry doorly zoo and aquarium .
tridacna squamosa ( veneroida : cardiidae ) fluted giant clam by tricia poh shi min , 2015 , on taxo4254 .
tridacna squamosa ( veneroida : cardiidae ) fluted giant clam , tricia poh shi min , 2015 , on taxo4254 .
previous to this study it was thought that only one species of giant clam was found in the territory , tridacna squamosa ( fluted giant clam ) ,
he said .
his thesis is entitled
ecological assessment of the fluted giant clam , tridacna squamosa , in the northern territory , australia
.
what is a giant clam ? stories of divers trapped by giant clams are legendary , but completely untrue . five of the seven species of giant clam are found in the waters of north western australia . they include the largest of all clams , the giant clam ( tridacna gigas ) , whose shell can grow up to 140 centimetres long and weigh up to 260 kilograms . the others are the fluted giant clam ( tridacna squamosa ) , the burrowing or crocus clam ( tridacna crocea ) , the elongate giant clam ( tridacna maxima ) and , least like the others , the horse - hoof clam ( hippopus hippopus ) .
can artificial substrates enriched with crustose coralline algae enhance larval settlement and recruitment in the fluted giant clam ( tridacna squamosa ) ? a study of singapore ' s fluted giant clams by mei lin neo , peter a . todd , serena lay - ming teo and loke ming chou on hydrobiologia , jun 2009 .
also known as bivalves , molluscs , clams , fluted clam , fluted giant clam seashell , scaly giant clam , scaly clam , scaled clam and squamosa clam . found on coral and rocky reefs and in lagoons . they feed on plankton . highly variable in colour . length 40cm depth 2 - 25m widespread indo - pacific most bivalves are permanently anchored in fissures or depressions in the rock surface of the reef , some may become covered in algae and other marine life . other bivalves swim free , either by a well developed foot or propelled along by a jet of water from their mantle cavity .
the fluted giant clam is usually firmly attached to a hard surface . sisters island , jan 04 the burrowing giant clam are often embedded inside corals . pulau hantu , mar 05 when submerged , the fleshy body expands like thick lips ! pulau hantu , feb 06 pulau semakau , mar 05
embed this arkive thumbnail link (
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after traditional owners expressed concerns the fluted giant clam was on the brink of extinction , charles darwin university phd graduate , shane penny , began his search to find out more about these colourful giants .
dr penny said his research raised some interesting questions about the genetics of the fluted giant clam in the northern territory waters , which he found to be genetically distinct from other species in south east asia .
todd pa , guest jr ( 2008 ) giant clam conservation and research in singapore . tentacle 16 : 24 .
the largest of all mollusks , the giant clam prefers the warm waters around australia ' s great barrier reef .
eckman w , vicentuan - cabaitan k & todd pa ( 2014 ) observations on the hyposalinity tolerance of fluted giant clam ( tridacna squamosa , lamarck 1819 ) larvae . nature in singapore , 7 : 111–116 .
found at the sandy bottom of coral reefs at depths of around 15 to 20 metres , the fluted clam is typically anchored amidst acropora corals ( 9 ) .
a researcher who has spent the past six years scouring the territory ' s coastline in search of a disappearing giant clam , has discovered three new clam species in northern australian waters .
dr shane penny has spent the past six years scouring the territory ' s coastline in search of giant clam species .
the fluted clam is classified as least concern ( lc ) on the iucn red list ( 1 ) , and listed on appendix ii of cites ( 3 ) .
this means it looks very similar to one or more common giant clam species , but they are genetically distinct .
neo ml , todd pa , chou lm & teo sl - m ( 2011 ) spawning induction and larval development in the fluted giant clam , tridacna squamosa ( bivalvia : tridacnidae ) . nature in singapore , 4 : 157–161 .
where do they live ? giant clams live in all of the marine parks in western australia’s north - west , in protected shallow water areas on the shore side of coral reefs . the giant , burrowing and horsehoof clams are found only in the central indo - pacific . the elongate giant clam is found as far south as the houtman abrolhos islands off geraldton and extends to south africa . the fluted giant clam is also widely distributed as far as africa , japan and south to the north west cape .
the fluted clam is known from the red sea and east african coast across the indo - pacific to the pitcairn islands , and an introduced population exists in the waters around hawaii ( 2 ) .
citation : neo ml , erftemeijer pla , van beek jkl , van maren ds , teo sl - m , todd pa ( 2013 ) recruitment constraints in singapore ' s fluted giant clam ( tridacna squamosa ) population—a dispersal model approach . plos one 8 ( 3 ) : e58819 . urltoken
dr penny surveyed 17 sites across the top end , to uncover more about what was thought to be the only species of giant clam found in the territory .
the fluted clam ( tridacna squamosa ) , also known as the scaled clam , can be identified by the large , leaf - like fluted scales on its shell ( 4 ) ( 5 ) , which are often used as shelter by organisms such as small crabs , clams , and other invertebrates ( 6 ) . the mantle is normally brown , generally mottled with vivid green and blue spots or wavy lines ( 5 ) ( 7 ) ( 8 ) .
fluted giant clam tridacna squamosa family tridacnidae updated oct 2016 where seen ? this beautifully sculptured giant clam is sometimes seen on our undisturbed southern shores , near living reefs . features : 15 - 30cm . the two - part shell has 5 - 6 rows of deep open flutes on the valves . the wavy shell opening faces the sunlight , while the hinged side is firmly attached to rocks or coral rubble in relatively shallow water near living reefs . it does not burrow into coral . status and threats : the fluted giant clam ( tridacna squamosa ) is listed as ' endangered ' on the red list of threatened animals of singapore . according to the singapore red data book :
large specimens have virtually disappeared from our shores . young specimens are occasionally but infrequently seen
.
unlike most other bivalves , the giant clam harbours symbiotic zooxanthellae ( a kind of single - celled algae ) in its fleshy body . the zooxanthellae produce food through photosynthesis which it shares with the clam . to maximise the productivity of its
farm
, the clam faces the shell opening ( and thus the body containing the algae ) to sunlight .
the fluted clam is bred in captivity in a number of countries , supplying domestic and international demand . harvest of wild specimens is either regulated or prohibited completely in many range states , although illegal harvesting may still occur ( 2 ) .
neo mei lin & loh kok sheng . 5 september 2014 . giant clam shells ‘graveyard’ at semakau landfill , tridacna squamosa . singapore biodiversity records 2014 : 248 - 249 .
how you can protect the giant clam : if you see a giant clam please marvel at its beautiful appearance and colouring but leave it for others to enjoy . you may not collect shells , even those that are dead , from below the high water mark of most marine parks in wa , as they often provide homes for other marine animals .
fluted giant clam ( tridacna squamosa ) in the bivalves section by j . m . poutiers in the fao species identification guide for fishery purposes : the living marine resources of the western central pacific volume 1 : seaweeds , corals , bivalves and gastropods on the food and agriculture organization of the united nations ( fao ) website .
mei lin neo , paul l . a . erftemeijer , jan k . l . van beek , dirk s . van maren , serena l - m . teo , peter a . todd . 13 march 2013 . recruitment constraints in singapore ' s fluted giant clam ( tridacna squamosa ) population—a dispersal model approach . plos one .
conservation status : giant clams are very common in many parts of northern australia .
heslinga ga , watson tc , isamu t ( 1990 ) giant clam farming . pacific fisheries development foundation ( nmfs / noaa ) , honolulu , hawaii , usa . 179 p .
the giant clam gets only one chance to find a nice home . once it fastens itself to a spot on a reef , there it sits for the rest of its life .
he said using underwater videos , genetics and traditional ecological knowledge , he was able to confirm that giant clam species are a lot more diverse in our northern waters than previously thought .
what they eat and how : giant clams filter water through their gills to extract tiny animals and / or minute plants for food . all giant clams also contain microscopic algae , known as zooxanthellae , in their mantles . the algae ( tiny plants ) produce food that can also be used by the clam . these microscopic plants contribute to the beautiful colours and patterns on the clam .
distribution patterns of giant clam larvae on local coral reefs at the end of transport phase for the three spawning periods : a ) 22 january , b ) 10 april and c ) 18 june 2004 .
giant clam ( tridacna squamosa ) tan , leo w . h . & ng , peter k . l . , 1988 . a guide to seashore life . the singapore science centre , singapore . 160 pp .
the giant clam has an extensive digestive system to extract the nutrients produced by the symbiotic algae . and enlarged excretory organs to deal with the large load of by - products of the algae . although giant clams are highly dependent on the symbiotic algae , they are still able to filter feed like other bivalves .
do giant clams trap divers in their shells ? this myth dispelled on the psychedelic nature blog .
what do they look like ? the most obvious feature of the giant clams is their beautifully patterned deep blue mantle , which can be seen between the gaping shells . they also have light and pressure - sensitive spots that look like a row of eyes along the edge of the mantle . the shells of most species of giant clam are white , though the horsehoof clam has cream shells with reddish spots . the shells are extremely thick .
deboer ts , subia md , ambariyanto , erdmann mv , kovitvongsa k , et al . ( 2008 ) phylogeography and limited genetic connectivity in the endangered boring giant clam across the coral triangle . conserv biol 22 : 1255–1266 .
the adductor muscle of the giant clam is actually considered a delicacy , and overharvesting of the species for food , shells , and the aquarium trade have landed it on at least one group ' s
vulnerable
list .
charles darwin university phd graduate shane penny speaking about his research on giant clams in the northern territory .
egg and larval transport was modelled using a three - dimensional ( 3d ) hydrodynamic model and an eulerian transport model coupled with mathematical definitions of larval characteristics , including estimates of sedimentation velocity , growth , behaviour and development of giant clam larvae .
giant clams can live to 30 - 40 years , the largest giant clams can live up to 100 years [ but ] what i found is a lot of our population seem to be about 10–18 years .
threats : thankfully , most australians would not molest , harm or remove a living giant clam and they are generally left on the reef for all to enjoy . in some other countries , however , they are taken for their meat and shells .
hopefully my work and the genetics as well highlights how special some of these populations of giant clams are .
when tridacna clams first attain sexual maturity , they are male , but about a year later become hermaphrodites , possessing both male and female reproductive organs . however , the release of sperm and eggs are separate in order to prevent self - fertilisation , although self - fertilisation can occur . the breeding season of the fluted clam occurs in winter ( 11 ) .
it is a mistaken belief that divers can be trapped underwater if the giant clam closes over their foot or hand . many of these peaceful clams can ' t even close their shells completely . they certainly don ' t eat people ! more about this on the
james r . guest , peter a . todd , eugene goh , balasubramaniam s . sivalonganathan , konda p . reddy . 10 august 2007 . can giant clam ( tridacna squamosa ) populations be restored on singapore ' s heavily impacted coral reefs ? aquatic conservation .
dr penny said understanding the diversity of giant clams had important consequences for conservation and the future management of the species .
the fluted clam is a popular food item and is traded domestically and internationally , with 34 countries recorded to export the species over the period from 1994 to 2003 ( 2 ) . live specimens have also been exported for the aquarium trade ( 2 ) . however , export has reduced and is now minimal , with significant international trade only really coming from the solomon islands ( 2 ) .
dr penny said he would work with traditional owners into the future to ensure the conservation of giant clams in top end waters .
munro pe , editor ( 1993 ) genetic aspects of conservation and cultivation of giant clams . iclarm conference proc 39 . 47 p .
dr penny said the biggest threat to giant clams in northern australian waters was a high mortality rate in their early years of maturity .
giant clams have a wildly undeserved reputation as man - eaters , with south pacific legends describing clams that lie in wait to trap unsuspecting swimmers or swallow them whole . no account of a human death by giant clam has ever been substantiated , and scientists say its adductor muscles , used to close the shell , move far too slowly to take a swimmer by surprise . even the largest specimen would simply retreat into its shell rather than attempt to sample human prey .
copland jw , lucas js , editors ( 1988 ) giant clams in asia and the pacific . aciar monograph no . 9 . 274 p .
gomez ed , mingoa - licuanan ss ( 2006 ) achievements and lessons learned in restocking giant clams in philippines . fish res 80 : 46–52 .
giant clams are considered a delicacy and in some places , an aphrodisiac . the large shells of these magnificent creatures are often turned into tacky souvenirs like ash - trays . there are efforts to cultivate giant clams on a commercial basis so as to reduce over - collection of wild clams .
there was something going on in the environment that was causing this high mortality of giant clams which was turning over the populations quite frequently .
giant clams achieve their enormous proportions by consuming the sugars and proteins produced by the billions of algae that live in their tissues . in exchange , they offer the algae a safe home and regular access to sunlight for photosynthesis , basking by day below the water ' s surface with their fluted shells open and their multi - colored mantles exposed . they also use a siphon to draw in water to filter and consume passing plankton .
giant clams mature first as males then eventually become hermaphrodites , producing both eggs and sperm . sperm is released first , probably to avoid self fertilisation .
one of the things i discovered was that a lot of these populations of giant clams in the northern territory are quite young ,
he said .
ellis s ( 1998 ) spawning and early larval rearing of giant clams ( bivalvia : tridacnidae ) . center for tropical and subtropical aquaculture publication number 130 . 55 p .
neo ml & todd pa ( 2013 ) conservation status reassessment of giant clams ( mollusca : bivalvia : tridacninae ) in singapore . nature in singapore , 6 : 125–133 .
in some areas we had some of the highest densities of giant clams , of this particular species , in the northern territory and the wider indo - pacific region .
dr penny said despite protection under international treaties , giant clams continued to be harvested and were rapidly becoming extinct near easily accessible sites , particularly in south - east asia .
neo ml , todd pa ( 2012 ) giant clams ( mollusca : bivalvia : tridacninae ) in singapore : history , research and conservation . raffles b zool 25 : 67–78 .
green a , craig p ( 1999 ) population size and structure of giant clams at rose atoll , an important refuge in the samoan archipelago . coral reefs 18 : 205–211 .
while analysing genetic tissue samples to establish the conservation status of giant clams in the territory , dr penny also detected a new species in western australia alongside researchers from the university of queensland .
mei lin neo and peter a . todd . 25 june 2013 . conservation status reassessment of giant clams ( mollusca : bivalvia : tridacninae ) in singapore . nature in singapore 2013 6 : 125–133
in the north central great barrier reef . in : copland jw , lucas js , editors . giant clams in asia and the pacific . aciar monograph no . 9 , canberra , australia . pp . 89–94 .
in relation to reef reseeding and mariculture . in : copland jw , lucas js , editors . giant clams in asia and the pacific . aciar monograph no . 9 , canberra , australia . pp . 78–81 .
mei lin neo , peter a . todd . 6 mar 2012 . population density and genetic structure of the giant clams tridacna crocea and t . squamosa on singapore’s reefs . aquatic biology vol . 14 : 265–275 .
normally the species would co - occur with other giant clams but my research has shown in shore they are in very high abundance on some reefs and that makes them quite significant within this south east asia region .
giant clams are broadcast spawners with high fecundity but poor early life survivorship [ 9 ] . published recruitment studies of giant clams are few in number [ 10 ] , [ 11 ] , and none address larval dispersal mechanisms despite the well - documented importance of larval transport for many marine invertebrate species [ 12 ] , [ 13 ] . with a planktonic phase of approximately nine days [ 14 ] , their larvae are likely to have a substantial dispersal capability ( as larvae can potentially be transported hundreds of kilometres in that timeframe ) , which may facilitate connectivity among populations [ 15 ] , [ 16 ] . conversely , results from giant clam genetic studies have indicated restricted gene flow , suggesting lower levels of exchange [ 17 ] , [ 18 ] . ocean current patterns have been invoked to explain such genetic divergences among marine invertebrate populations [ 19 ] , as they can influence temporal and spatial physical processes that potentially restrict larval dispersal and gene flow [ 20 ] , [ 21 ] .
bell jd ( 1999 ) restocking of giant clams : progress , problems and potential . in : howell br , moskness e , svasand t , editors . stock enhancement and sea ranching . blackwell science , oxford . pp . 437–452 .
video clips of singapore giant clams from links shared by neo mei lin on her blog . an animal behavior film project in partial fulfilment for nus lsm4253 animal behaviour ay2008 / 09 . done by : neo meilin pamela soo daniel storisteanu nicholas yap
to assess low - density constraints to fertilisation efficacy , dispersal potential of giant clam eggs between donor and recipient clams within known singapore localities was analysed from the point of release ( 0 hours ) to 6 hours later ( estimated viability of eggs ; unpublished data ) . connectivity between t . squamosa individuals was limited to either the dense clusters of > 2 clams ( raffles lighthouse and biola , beting bemban besar and semakau ) or paired clam individuals that were in close proximity ( within jong and within kusu ) ( table 4 ) . based on the results , for eggs to arrive over their nearest - neighbour clams within the period of their viability , clams must be within a vicinity of no more than 2000 m . however , the number of eggs arriving at recipient clams varied across sites , regardless of time or distance ( table 4 ) .
m . l . neo and peter a . todd . jun 2012 . giant clams ( mollusca : bivalvia : tridacninae ) in singapore : history , research and conservation . raffles bulletin of zoology 2012 supplement no . 25 : 67 - 78 .
15 - 40cm . giant clams are among the largest bivalves to have ever existed on our planet ! the two - part shell is thick and usually has a wavy opening that never closes completely . the shell opening faces the sunlight , while the hinged side is at the bottom , attached to a hard surface by a large byssus mass that emerges from a gap between the valves near the hinge . some giant clams burrow into coral , with most of the shell hidden and only the shell opening facing sunlight .
the shell opening never closes completely even at low tide , and the body is exposed . the body expands under water and appears like colourful thick lips in between the wavy shell opening . the brightly coloured spots in the body protect against excessive sun . the clam has transparent lenses that focus sunlight onto the algae that are found deeper in the flesh .
dispersal patterns from regional donor reefs to singapore—this scenario examined the potential of regional coral reefs to donate giant clam larvae to reefs in singapore ( i . e . recipient reefs ) , modelled using the hydrodynamics simulated for 22 january , 10 april and 18 june 2004 over a period of 15 days of transport . eight release points , i . e . possible donor sites , were examined individually ( 8 separate runs ) : koh racha yai ( thailand ) , port dickson ( malaysia ) , north and south batam , bintan , bangka - belitung and anambas ( all indonesia ) , and tioman island ( malaysia ) ( see figure 1a for exact localities ) .
giant clam larval transport success appears to be largely driven by variability in annual hydrodynamics ( for the year that was modelled ) . consistent westward residual currents in the outer straits of singapore during january and in april drive larval transport towards the west , with higher larval retention in the northwestern reefs . in contrast , the lack of residuals in june allows much higher retention in the northern and southern reefs with higher larval settlement . in singapore , broadcasting corals annually spawn in late march or mid april [ 66 ] . while the moderate residuals during this time may be favourable for coral larvae with short settlement periods [ 73 ] those with longer life cycles , such as giant clams , may experience dilution of larvae into the outer straits when released during this period . the near absence of residual currents in june favours retention of clam larvae , reducing offshore dispersal . larval mortality also greatly influences transport success , which in turn affects juvenile recruitment on reefs [ 60 ] . sedimentation velocity and diel vertical migration , however , have negligible effects on transport success , suggesting that ocean currents primarily influence larval dispersal [ 74 ] . results from this modelling study should be interpreted with caution , bearing in mind the various assumptions made . the transport success and dispersal distances predicted by the model probably do not equate to actual recruitment success in the field .
stage 5 : during the last metamorphosis stage , the velum and fully developed foot of pediveligers allows them to alternately swim and crawl on the benthos ; over time , these larvae become increasingly sedentary [ 11 ] , [ 56 ] . transport is completed after this metamorphosis stage . in stage 5 , juveniles ( 8 to 9 days old ) either continue to exhibit the behaviour of stage 4 larvae , or settle onto the coral reefs . giant clam larvae respond to settlement cues such as the presence of crustose coralline algae [ 11 ] and / or conspecific adults [ 57 ] , [ 58 ] , both of which are found on coral reefs . hence , in our model , larval settlement was mimicked when larvae passed over coral reef areas ( see figure 2 ) .
egg dispersal potential—time - series plots describing the arrival time of eggs over certain clams was determined by plotting larval density ( number per m 2 ) in the model at each observation point ( usually one grid cell ) showing the accumulation of eggs over any specified coral reef area . donor - recipient clams were identified with the following parameters : distance between clam pairs , arrival time of eggs , and peak number of eggs arrived per m 2 .
as giant clams continue to be threatened by anthropogenic activities , active conservation measures are needed [ 51 ] , [ 85 ] , [ 86 ] . their sedentary mode of life makes giant clams highly amenable candidates for restocking and stock enhancement [ 9 ] , [ 51 ] and depleted clam populations [ 10 ] , [ 57 ] are currently being restored through these means in fiji , palau and the philippines [ 9 ] , [ 30 ] , [ 58 ] . however , none of these efforts accounted for whether the transplant sites were effective as source habitats to encourage recruitment in sink sites [ 87 ] . the designation of effective restocking sites requires closer examination of metapopulation dynamics , habitat quality and recruitment processes [ 67 ] , [ 85 ] and their potential to augment recruitment [ 88 ] , [ 89 ] . the results from the present study enable the identification and selection of potential source and sink sites for more effective restocking efforts . metapopulation enhancement can thus be optimised by restocking source populations and subsequently will encourage recruitment in sink populations via larval dispersal [ 67 ] . an added strategy to enhance current metapopulations of t . squamosa in singapore waters is to perform in situ spawning induction of populations during favourable current periods ( e . g . june ) to maximise larval retention and settlement .
spawning seasonality in t . squamosa varies among localities [ 4 ] , [ 48 ] , [ 49 ] but mature gametes can generally be found throughout most of the year [ 50 ] . since the actual spawning periods in singapore are unknown , three time points representing local seasonality were selected to investigate the effects of spawning times on recruitment success . spawning in giant clams often occurs during full moon or new moon [ 51 ] , [ 52 ] and this was therefore taken into account with the transport of either eggs or larvae modelled assuming each simulation was a single spawning event on the following lunar periods : 22 january ( new moon ) , 10 april ( full moon ) and 18 june ( new moon ) 2004 . giant clams are benthic spawners , hence all eggs were released in the lowest 10 % of the model layer representing the water column .
sensitivity analyses of the release times indicated that successful settlement of giant clam larvae on singapore ' s reefs could potentially be achieved throughout the year , with the greatest chances of successful larval settlement when gametes were released during june . density of larval settlement on reefs increased over the months : january < april < june ( figure 3 ) . january is the period with the greatest westward flow velocity whereas eastward flow peaks in june–july ( with april being the transitional period ) ; settlement is therefore expected to decrease again after june–july . settlement success varied among islands , where in january and april , the northwestern reefs had higher densities of settled larvae , while northern and southern reefs had higher densities of settled larvae in june ( figure 3 ) . variations in the larval sedimentation velocity , following a diel vertical migration pattern , did not affect larval transport success ( figure 4 ) . however , mortality rates for each larval stage had a significant effect on transport success . highest mortality rates ( see table 1 ) resulted in almost no larval settlement on the reefs ( figure 4 ) .
behaviour : adult giant and horsehoof clams are so heavy that they do not need to attach themselves to the seabed . the other species have byssal threads to attach themselves to the seafloor or other surfaces . if they sense danger , such as a diver swimming overhead , the shell valves are clamped shut by a large muscle . the clams are capable of producing pearls that weigh up to six kilograms , but they lack the lustrous sheen of those produced by the pearl oyster .
transport of giant clam eggs and larvae was modelled using the water quality module of delft3d ( delft3d - waq ) [ 43 ] . delft3d - waq is a transport model that has been successfully applied to dispersal simulations of seagrass seeds , fish larvae and mangrove propagules [ 13 ] , [ 44 ] , [ 45 ] , [ 46 ] . the model calculates the concentrations of ‘substances’ ( in this case : either eggs or larvae ) for each time - step as a function of the initial concentrations , advective and dispersive transport , and biological characteristics and processes . delft3d - waq is an eulerian model based on the finite - volume method ( i . e . multiplication of fluxes with concentrations to obtain masses across internal and external boundaries ) . both finite - volume methods and particle tracking model approaches can ( in principle ) provide comparable results [ 47 ] . with our focus on mid - field and far - field effects , the waq model ( including the extensive and well - validated biological process library ) is more appropriate than a particle - tracking method . the main advantages of particle - tracking are that it offers sub - grid model resolution as well as the opportunity to track individual seedlings , both of which are not very relevant to our study . the actual water system is represented within delft3d - waq by means of computational elements ( segments ) . the flow between segments is derived from the hydrodynamic model ( delft3d - flow ) of the same resolution ( i . e . down to 100 m around the southern islands ) .
the poor larval connectivity from regional reefs to singapore could be explained by the strong surface currents flowing between the andaman sea and south china sea during the monsoons [ 75 ] that move larvae out of the singapore strait with little retention . poor larval connectivity with most external potential donor reefs may also be attributed to peninsular malaysia . phylogeographic studies of marine invertebrates and mangroves have shown that this peninsular acts as a barrier that disrupts gene flows between the east and west coasts , corresponding to the western sunda shelf barrier [ 18 ] , [ 19 ] , [ 76 ] . population genetic breaks in t . crocea populations on the sunda shelf and western indonesia also provide evidence for limited connectivity in this region [ 17 ] , [ 18 ] . in contrast , offshore coral reefs located to the southeast of singapore , combined with the favourable westward residuals along the straits [ 77 ] and absence of significant land barriers , encourage high larval settlement and retention . as predicted by the model , t . squamosa populations in batam and bintan could provide a significant stock of source larvae for the clam - depauperate reefs in singapore waters ; possibly facilitating the natural recovery of populations .
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tridacna clams have muscles for opening and closing their shell and a foot for attaching themselves to rocks . they breathe through gills and feed through a mouth ( 10 ) . most clams fulfill their nutritional requirements by filter feeding and absorbing dissolved organic compounds from the water , but tridacnid clams have gone further than this by using zooxanthellae algae in their tissue to manufacture food for them ( 10 ) ( 11 ) . the zooxanthellae transforms carbon dioxide and dissolved nitrogen , such as ammonium , into carbohydrates and other nutrients for their hosts ( 11 ) .
lukan , e . m . ( 2000 ) critter corner : tridacna squamosa . fish ‘n’ chips : a monthly marine newsletter , 2000 : 0 . available at : urltoken
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invertebrates animals with no backbone , such as insects , crustaceans , worms , molluscs , spiders , cnidarians ( jellyfish , corals , sea anemones ) , echinoderms , and others . mantle in molluscs , the fold of skin lining the outer surface of the shell , which encloses a space ( the mantle cavity ) containing the gills .
lukan , e . m . ( 2000 ) critter corner : tridacna squamosa . fish ‘n’ chips : a monthly marine newsletter , 2000 . available at : urltoken
lukan , e . m . ( 1999 ) critter corner : tridacnid clams : the basics . fish ‘n’ chips : a monthly marine newsletter , 1999 . available at : urltoken
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funding : the research presented in this work was carried out as part of the building with nature singapore supportive modelling project ( 1201442 . 002 ) . this study was also supported by the national parks board ' s coastal & marine environment grant number r - 154 - 000 - 504 - 490 and singapore - delft water alliance ' s marine & coastal research programme ( theme 2 ) grant number r - 264 - 001 - 001 - 272 . the funders had no role in study design , data collection and analysis , decision to publish , or preparation of the manuscript .
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here we used a locally refined version [ 39 ] of the singapore regional model ( see [ 40 ] ) . this model is composed of three domains [ 41 ] . the model ' s outer domain has a grid cell size decreasing from 30 km near the boundaries to ∼300 m around singapore ( see figure 1 ) . the middle domain ( in red ) has the same resolution ( 300 m ) , but the local domain ( in blue ) around singapore ' s islands are refined by a factor three compared to the outer and middle domains , leading to grid cell sizes down to 100 m .
this model is composed of 3 domains . a ) the overall outer domain including peninsular malaysia and the 8 regional release points ( green dots ) . the red and blue domains represent the refined grid resolutions for singapore ' s coastal waters . b ) the blue grid encompasses the waters surrounding singapore ' s southern islands . the red dots represent the 28 release points ( i . e . the positions of t . squamosa in singapore ) .
the model was forced at its three open boundaries ( the andaman sea in the northwest , the south china sea in the northeast , and the java sea in the southeast ) by 8 tidal constituents and a mean annual cycle of the monsoon - induced water level , derived from 15 years of topex - poseidon and jason - 1 satellite altimetry ( see [ 40 ] , [ 42 ] ) .
the hydrodynamics in singapore coastal waters are complex , with predominantly semi - diurnal water level variations but diurnal currents . superimposed on this are compound tides generated by semi - diurnal and diurnal constituents with a periodicity equal to the spring neap cycle ( approximately 2 weeks ) , and monsoon currents [ 39 ] . within singapore ' s southern islands area , dominant flow is eastward from april / may to september / october , and westward during the other months . this seasonal variation , and the two - weekly variations , is well reproduced by the model . it should be noted that the stations banyan and sawa are within the southern islands area , where large - scale clockwise circulation generates more pronounced eastward currents than in the open singapore strait south of the islands [ 41 ] . therefore residual currents within the southern islands group in april tend to be directed eastward while in the open strait they may be directed westward .
specific release points outside of singapore ( 8 points ) ( figure 1a ) and within the southern islands ( 28 points ) ( figure 1b ) were selected as initial spawning points for modelling the transport of eggs and larvae . factors that are known to affect larval growth and development were incorporated into the transport model : spawning periods , different stages of larval development ( with different behavioural rules ) , larval swimming behaviour and mortality of larvae at respective stages . the details of larval stages , specific behavioural rules , processes and parameters incorporated into the model are described below .
in the model , five developmental stages [ 25 ] were distinguished based on their behavioural and physical traits in relation to horizontal and vertical transport .
stage 1 : passive horizontal pelagic transport of eggs homogenously distributed within the water column . at day 0 , eggs were assumed to have neutral buoyancy while being passively transported by currents .
stage 2 : passive horizontal pelagic transport of trochophores as in stage 1 . assuming all the released eggs were fertilised , upon hatching after 24 hours , the trochophores have limited overall locomotion [ 53 ] and are largely transported by currents . with their poor swimming ability , vertical transport with diel migration is limited at this stage ( see “sensitivity analyses” below ) . the distinction between eggs and pelagic trochophores was made to facilitate growth parameter settings such as mortality rates and sedimentation velocity .
stage 3 : passive horizontal pelagic transport of veliger larvae . locomotion of early veligers ( 2 to 4 days old ) is primarily through ciliary band movement [ 54 ] , [ 55 ] , which affects vertical position but is negligible in the horizontal dimension compared to the strength of the currents . therefore , only vertical movement was simulated in the model , by varying the larvae ' s sedimentation velocity ( see “sensitivity analyses” below ) . stage 3 mortality rates and sedimentation velocity were different to those in stage 2 .
stage 4 : passive horizontal pelagic transport of veliger larvae . in stage 4 ( 5 to 7 days old ) , late veligers develop a primitive foot—an initiation of their sedentary lifestyle , but still rely on swimming to move between the surface water and bottom layers . the sedentary component of stage 4 distinguishes it from stage 3 .
coral reef areas ( in colour ) among singapore ' s southern islands used to estimate transport success . each colour corresponds to a distinct potential sink site .
growth parameters of the various stages were estimated using existing data obtained from laboratory experiments [ 25 ] and mariculture literature [ 53 ] , [ 59 ] , [ 60 ] . the average values for concentrations of egg release and development rates for each stage were chosen as default model settings ( see “sensitivity analyses” below ) . for each dispersal scenario , the transport model was run for a period of 15 days [ 52 ] as previous work indicated this was the time during which t . squamosa larval settlement occurs ( unpublished data ) .
tridacna squamosa have a high fecundity , releasing eggs of 420 , 000 to 46 , 000 , 000 eggs released per individual each spawning [ 25 ] , [ 49 ] . in the model , a fixed average initial concentration of 4 , 500 , 000 eggs was released over a 15 - minute time step . based on the sensitivity analyses , default settings were used for all transport models . three main scenarios were considered in the investigation of larval connectivity and the effects of hydrodynamics on larval recruitment .
dispersal patterns within southern islands , singapore—this scenario examined source - sink dynamics via larval dispersal within the southern islands reefs , modelled using the hydrodynamics simulated for 10 april 2004 over a period of 15 days of transport . transport model was performed in april 2004 based on the mass coral spawning in singapore [ 66 ] , assuming that it was an ‘ideal’ period for larval dispersal . for this study , source reefs are habitats optimal for restocking while sink reefs are habitats where restocking is likely to be fruitless , but can serve as locations for the recruitment of larvae via source reefs [ 67 ] . to identify respective source and sink reefs within the southern islands , reefs supporting the current t . squamosa population ( n = 28 ) in singapore [ 3 ] were individually examined as possible sources of larvae in this scenario . release points were as follows : raffles lighthouse 01–02 , biola 01–03 , senang , pawai , berkas , sudong , salu , beting bemban besar 01–02 , terumbu raya , semakau 01–05 , terumbu semakau , jong 01–02 , terumbu pempang tengah , hantu , sisters 01–02 , kusu 01–02 and cyrene .
egg dispersal potential—this scenario examined egg dispersal movement within the southern islands reefs ; modelled using the hydrodynamics simulated for 10 april 2004 over a period of 6 hours . as egg masses are known triggers for eliciting a spawning response ( resulting in either release of sperm or eggs ) in adult clams [ 68 ] , [ 69 ] , transport of eggs was of greatest interest . release points represented the current t . squamosa population ( as described earlier ) and eggs were released at each location ( 28 separate runs ) .
dispersal patterns from regional donor reefs to singapore—at each time point , the percentage of successful settlers that had arrived on singapore ' s coral reefs at the end of the model run was summed to calculate transport success from respective donor locations .
dispersal patterns within southern islands , singapore—the density of successful settlers ( i . e . number of larvae per 10 , 000 m 2 ) that had arrived on the local coral reefs was computed at the end of the model run . the model grid area was subdivided into 19 reef sections ( figure 2 ) , delimited by the 20 m - depth contour . for each section , the number of larvae per compartment was summed to determine the transport success .
sensitivity testing on the effect of mortality and sedimentation velocity settings on numbers of settled larvae for three different timings of release ( january , april , june ) .
transport successes of larvae to singapore from five donor localities in neighbouring countries ( koh racha yai , port dickson , bangka - belitung , tioman island and anambas ) were very poor ( ∼0 % ) ( table 2 ) . three other donor localities ( north and south batam , and bintan ) had more positive transport success . larvae from north batam had the highest settlement success of 61 . 58 % on singapore ' s reefs in june , while bintan had high settlement success throughout the year ( january : 30 . 86 % , april : 44 . 53 % , june : 19 . 40 % ) ( table 2 ) .
a summation matrix of total bottom larvae was produced to identify the prospective source and sink sites on southern islands reefs for analysis of local reef connectivity . assuming all 19 sections were potential sink sites , larval transport success ( per 10 , 000 m 2 of reef area ) was low among southern islands reefs ( table 3 ) . the eastern islands , such as sisters ' and kusu islands ( figure 2 ) , could be potential source reefs as , when larvae were released from these locations , surrounding reefs were able to receive high numbers of settled larvae per 10 , 000 m 2 ( table 3 ) . four most potential sink sites were identified : cyrene , tekukor , raffles lighthouse and salu , where from a single source site ( sisters 02 ) each of the mentioned reefs received 68 . 6 , 50 . 2 , 46 . 2 and 38 . 8 settled larvae per 10 , 000 m 2 respectively ( table 3 ) . coral reefs found within the central area , such as pulau hantu , semakau , pulau sudong ( figure 2 ) , were generally poor or moderate sources and / or sinks , with the majority of sites receiving fewer than 20 larvae per 10 , 000 m 2 .
thank you to harriette holzhauer for providing gis support . the authors gratefully acknowledge the support and contributions of the ecoshape ‘building with nature’ ( bwn ) programme .
conceived and designed the experiments : mln pe jvb dvm pt . performed the experiments : mln pe jvb dvm . analyzed the data : mln pe jvb dvm . contributed reagents / materials / analysis tools : pe jvb dvm . wrote the paper : mln pe jvb dvm pt st .
) populations be restored in singapore ' s heavily impacted coral reefs ? aquat conserv 18 : 570–579 .
wada sk ( 1954 ) spawning in tridacnid clams . jpn j zool 11 : 273–285 .
cowen rk , lwiza kmm , sponaugle s , paris cb , olson db ( 2000 ) connectivity of marine populations : open or closed ? science 287 : 857–859 .
gascoigne jc , lipcius rn ( 2004 ) allee effects in marine systems . mar ecol prog ser 269 : 49–59 .
hobday aj , tegner m , haaker pl ( 2001 ) over - exploitation of a broadcast spawning marine invertebrate : decline of the white abalone . rev fish biol fisher 10 : 493–514 .
heslinga ga , fitt wk ( 1987 ) the domestication of reef - dwelling clams . bioscience 37 : 332–339 .
, at michaelmas reef , central great barrier reef , australia . aust j mar fresh res 42 : 241–262 .
knights am , crowe tp , burnell g ( 2006 ) mechanisms of larval transport : vertical distribution of bivalve larvae varies with tidal conditions . mar ecol prog ser 326 : 167–174 .
bolle lj , dickey - collas m , van beek jkl , erftemeijer pla , witte jij , et al . ( 2009 ) variability in transport of fish eggs and larvae . iii . effects of hydrodynamics and larval behaviour on recruitment in plaice . mar ecol prog ser 390 : 195–211 .
) populations from reefs in the western coral sea . coral reefs 11 : 135–141 .
becker bj , levin la , fodrie fj , mcmillan pa ( 2007 ) complex larval connectivity patterns among marine invertebrate populations . p natl acad sci usa 104 : 3267–3272 .


the red-faced crombec ( sylvietta whytii ) is a species of african warbler , formerly placed in the family sylviidae .

it is found in burundi , ethiopia , kenya , malawi , mozambique , namibia , rwanda , south sudan , tanzania , uganda , and zimbabwe .

its natural habitats are subtropical or tropical dry forests , subtropical or tropical moist montane forests , and subtropical or tropical dry shrubland .

red - faced crombec

red - faced crombec ( sylvietta whytii ) is a species of bird in the macrosphenidae family .
pearson , d . ( 2018 ) . red - faced crombec ( sylvietta whytii ) . in : del hoyo , j . , elliott , a . , sargatal , j . , christie , d . a . & de juana , e . ( eds . ) . handbook of the birds of the world alive . lynx edicions , barcelona . ( retrieved from urltoken on 9 july 2018 ) .
thank you for taking the time to provide feedback on the iucn red list of threatened species website , we are grateful for your input .
9 cm ; 8–12·5 g . a grey - backed crombec with plain tawny face . nominate race has top of head and upperparts light grey , face and underparts tawny - buff , paler on belly and . . .
this locally common resident in miombo & teak woodland and riparian forest is slightly smaller than the long - billed crombec . it can be further differentiated from the latter by its rufous face and underparts , as well as the lack of a grey eye stripe .
recommended citation birdlife international ( 2018 ) species factsheet : sylvietta whytii . downloaded from urltoken on 09 / 07 / 2018 . recommended citation for factsheets for more than one species : birdlife international ( 2018 ) iucn red list for birds . downloaded from urltoken on 09 / 07 / 2018 .
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del hoyo , j . , collar , n . j . , christie , d . a . , elliott , a . , fishpool , l . d . c . , boesman , p . and kirwan , g . m . 2016 . hbw and birdlife international illustrated checklist of the birds of the world . volume 2 : passerines . lynx edicions and birdlife international , barcelona , spain and cambridge , uk .
justification : this species has an extremely large range , and hence does not approach the thresholds for vulnerable under the range size criterion ( extent of occurrence < 20 , 000 km2 combined with a declining or fluctuating range size , habitat extent / quality , or population size and a small number of locations or severe fragmentation ) . despite the fact that the population trend appears to be decreasing , the decline is not believed to be sufficiently rapid to approach the thresholds for vulnerable under the population trend criterion ( > 30 % decline over ten years or three generations ) . the population size has not been quantified , but it is not believed to approach the thresholds for vulnerable under the population size criterion ( < 10 , 000 mature individuals with a continuing decline estimated to be > 10 % in ten years or three generations , or with a specified population structure ) . for these reasons the species is evaluated as least concern .
the global population size has not been quantified , but the species is described as locally fairly common ( del hoyo et al . 2006 ) . trend justification : the population is suspected to be in decline owing to the destruction of miombo woodlands for agriculture ( del hoyo et al . 2006 ) .
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proposed race nemorivaga ( nw zimbabwe ) usually considered indistinguishable from nominate . four subspecies currently recognized .
mearns , 1911 – sw ethiopia ( addis ababa s to yabelo and l abiata ) , se south sudan , ne uganda ( karamoja ) and nw kenya ( s turkana s to kapenguria ) .
sharpe , 1897 – uganda ( except ne ) , sw & c kenya , rwanda , burundi , n & c tanzania ( e to kilimanjaro and iringa ) .
ogilvie - grant , 1900 – se kenya and ne tanzania ( extending inland to tsavo , taveta and morogoro ) .
shelley , 1894 – se tanzania , malawi , n & c mozambique and zimbabwe .
song a thin “wee see - see , wee see - see” or “esee - sisi - seee , see - sisi - seee” , notes all on same pitch . . .
insects , including caterpillars ; also spiders ( araneae ) , small worms . forages mainly in trees or tall bushes , usually in pairs , commonly . . .
breeds just before or in early part of rains in e africa ; aug–dec in s . monogamous ; territorial . nest a thick - walled oval pouch with . . .
not globally threatened . locally fairly common ; generally common and widespread in e africa . density 3 pairs / 100 ha in brachystegia woodland in zimbabwe . adversely affected . . .
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recently delineated family , comprising macrosphenus , sphenoeacus , melocichla , achaetops , sylvietta and cryptillas # r ; in addition , graueria tentatively included here , but its affinities are still uncertain , as no molecular data published .
previously placed in a broad sylviidae ( see page 498 ) , or more recently in acrocephalidae . numerous forms described in “ sylviella ” , an unjustified emendation of present genus name .
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calls from one of a pair of birds moving at mid - height through dense scrub and open dry forest at the base of a tall cliff .
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this species has an extremely large range , and hence does not approach the thresholds for vulnerable under the range size criterion ( extent of occurrence < 20 , 000 km2 combined with a declining or fluctuating range size , habitat extent / quality , or population size and a small number of locations or severe fragmentation ) . despite the fact that the population trend appears to be decreasing , the decline is not believed to be sufficiently rapid to approach the thresholds for vulnerable under the population trend criterion ( > 30 % decline over ten years or three generations ) . the population size has not been quantified , but it is not believed to approach the thresholds for vulnerable under the population size criterion ( < 10 , 000 mature individuals with a continuing decline estimated to be > 10 % in ten years or three generations , or with a specified population structure ) . for these reasons the species is evaluated as least concern .
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english - german online dictionary developed to help you share your knowledge with others . more information ! contains translations by tu chemnitz and mr honey ' s business dictionary ( german - english ) . thanks on that account ! links to this dictionary or to single translations are very welcome ! questions and answers
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howard and moore 4th edition ( incl . corrigenda vol . 1 - 2 ) :
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i recorded this member of the almost tailles crombecs in september 2011 while birding the gardens of the seravo lion hill game lodge in the lake nakure national park , kenya .
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