anthozoa is a class of marine invertebrates which includes the sea anemones , stony corals , soft corals and gorgonians .

adult anthozoans are almost all attached to the seabed , while their larvae can disperse as part of the plankton .

the basic unit of the adult is the polyp ; this consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles .

sea anemones are mostly solitary , but the majority of corals are colonial , being formed by the budding of new polyps from an original , founding individual .

colonies are strengthened by calcium carbonate and other materials and take various massive , plate-like , bushy or leafy forms .

anthozoa is included within the phylum cnidaria , which also includes the jellyfish , box jellies and parasitic myxozoa and polypodiozoa .

the two main subclasses of anthozoa are the hexacorallia , members of which have six-fold symmetry and includes the stony corals , sea anemones , tube anemones and zoanthids ; and the octocorallia , which have eight-fold symmetry and includes the soft corals and gorgonians ( sea pens , sea fans and sea whips ) , and sea pansies .

the smaller subclass , ceriantharia , consists of the tube-dwelling anemones .

anthozoans are carnivores , catching prey with their tentacles .

many species supplement their energy needs by making use of photosynthetic single-celled algae that live within their tissues .

these species live in shallow water and many are reef-builders .

other species lack the zooxanthellae and , having no need for well-lit areas , typically live in deep-water locations .

unlike other members of this phylum , anthozoans do not have a medusa stage in their development .

instead , they release sperm and eggs into the water .

after fertilisation , the planula larvae form part of the plankton .

when fully developed , the larvae settle on the seabed and attach to the substrate , undergoing metamorphosis into polyps .

some anthozoans can also reproduce asexually through budding or by breaking in pieces .

more than 6,100 species have been described .

anthozoa

a . e . verrill , “additions to the anthozoa and hydrozoa of the bermudas . anthozoa , ” in
grzegorz jagodziński added the polish common name
koralowce
to
anthozoa
.
( anthozoa : hexacorallia : zoantharia ) from japan . fauna ryukyuana 29 : 37–40
( cnidaria : anthozoa : actiniaria ) from the gulf of mexico and caribbean .
( anthozoa : actiniaria ) from southern patagonia : morphological study and new records .
maggie whitson set
image of anthozoa
as an exemplar on
sabellida
.
anthozoa : blumentiere . . . staurozoa : stiel - oder becherquallen . . . cub…
( anthozoa , zoantharia , sphenopidae ) in okinawa , japan . biol bull 220 : 23–31
( cnidaria : anthozoa : zoantharia : sphenopidae ) from okinawajima island , japan . zookeys 606 : 11–24
( anthozoa : hexacorallia ) attached to eunicid worm tubes from the pacific ocean . zookeys 562 : 49–71
species ( anthozoa , tabulata ) from the lower devonian of colle ( spain , cantabrian mountains ) .
( anthozoa : hexacorallia ) from southwestern japan with description of two new species . zool sci 23 : 261–275
the oldest fossils seem to be medusae , but the most basal branch , anthozoa , has only polyps .
kotrc , b . 2005 . anthozoa : subgroups fossil groups . university of bristol . retrieved august 2 , 2008 .
nomenclature and biology of astrangia poculata ( = a . danae , = a . astreiformis ) ( cnidaria : anthozoa )
the oldest fossils seem to be of solitary forms , but the most basal branch , anthozoa , is primarily colonial .
( cnidaria : anthozoa : antipatharia ) supports classification of antipatharians within the subclass hexacorallia . mol phylogen evol 42 : 776–788 .
chen ca , odorico dm , ten louis m , veron jen , miller dj ( 1995 ) systematic relationships within the anthozoa ( cnidaria anthozoa ) using the 5′ - end of the 28s rdna . mol phylogenet evol 4 ( 2 ) : 175–183 .
s . cairns , c . den hertog , and c . arneson , “class anthozoa ( corals , anemones ) , ” in
the class anthozoa includes the sea anemones and corals . for anthozoans , the dominant stage in the life cycle is the polyp .
anthozoa is the largest of the four classes of cnidaria with over 6 , 000 species ( france 2004 ) . they are found worldwide in all oceans , from the arctic to the antarctic . anthozoa means
flower animals ,
which is descriptive of this class of invertebrates .
schmidt , h . 1974 . on evolution in the anthozoa . proceedings of the second international coral reef symposium 1 : 533 - 560 .
sanamyan , n . , & sanamyan , k . ( 1998 ) . some actiniaria from the commander islands ( cnidaria : anthozoa ) .
cairns sd ( 1995 ) the marine fauna of new zealand : scleractinia ( cnidaria anthozoa ) . nzoi mem . 103 . 210 p .
sexual - organisms in the anthozoa class can reproduce sexually by forming eggs and sperm , which fertilize like the other organism classes in cnidaria .
search for mesophotic octocorals ( cnidaria , anthozoa ) and their phylogeny : i . a new sclerite - free genus from eilat , northern red sea
may , a . 2006 , radiastraea ( anthozoa , rugosa ) from the . . . bulletin of geosciences , 81 , 151 - 162 .
the phylum cnidaria encompasses five classes : anthozoa , cubozoa , hydrozoa , scyphozoa , and staurozoa . anthozoa is the most speciose of these classes and is further subdivided into two diverse subclasses hexacorallia ( hard corals and sea anemones ) and octocorallia ( soft corals , sea pens , and gorgonians ) [
paulay g , puglisi mp , starmer ja ( 2003 ) the non - scleractinian anthozoa ( cnidaria ) of the mariana islands . micronesica 35 : 138–155
fautin , daphne g . and sandra l . romano . 2000 . anthozoa . sea anemones , corals , sea pens . version 03 october 2000 .
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fujii t , reimer jd ( 2011 ) phylogeny of the highly divergent family microzoanthidae ( anthozoa , hexacorallia ) from the pacific . zool scr 40 : 418–431
fautin , d . g . ( 2016 ) . catalog to families , genera , and species of orders actiniaria and corallimorpharia ( cnidaria : anthozoa ) .
daly m , fautin dg , cappola va ( 2003 ) systematics of the hexacorallia ( cnidaria : anthozoa ) . zool j linn soc 139 : 419–437 .
spp . ( dinophyceae , suessiales ) within closely related host genera : zoanthids ( cnidaria : hexacorallia : anthozoa ) as a case study . galaxea 10 : 3–13
( drayton in dana , 1846 ) ( cnidaria : anthozoa ) , two common actiniid sea anemones from the south east pacific with a discussion of related genera .
the anthozoa subphylum consists of sea anemones and corals . most anthozoa organisms are sessile creatures , and anemones found within the united states tidal zones have minimal toxicity . the sea anemone phyllodiscus semoni ( night or wasp - sea anemone ) located in the western pacific ocean is reported to cause fulminant dermatitis and acute renal failure in humans
] . here we show that paraphyletic anthozoa does not result from unbalanced taxon sampling . in addition , a principal component analysis of the amino acid composition ( additional file
england , k . w . , & robson , e . a . ( 1984 ) . a new sea anemone from south africa ( anthozoa , ptychodactiaria ) .
cairns sd ( 1999 ) cnidaria anthozoa : deep - water azooxanthellate scleractinia from vanuatu , and wallis and futuna islands . mem mus nat hist nat 180 : 31–167 .
anatomy and taxonomy of three species of sea anemones ( cnidaria : anthozoa : actiniidae ) from the gulf of california , including isoaulactinia hespervolita daly , n . sp .
( hydrozoans ) ; scyphozoa ( scyphozoans ) ; anthozoa ( anthozoa ns ) ; and cubozoa ( cubozoans ) . all cnidarians share several attributes , supporting the theory that they had a single origin . variety and symmetry of body forms , varied coloration , and the sometimes complex life histories of cnidarians fascinate layperson and scientist alike . inhabiting all marine and some…
presence of abyssoanthus sp . ( anthozoa : zoantharia ) in the mediterranean sea : indication of a new cold seep or of ecological tolerance of abyssoanthus to non - chemotrophic environments ?
chen , c . a . , d . m . odorico , m . ten lohuis , j . e . n . veron , and d . j . miller . 1995 . systematic relationships within the anthozoa ( cnidaria : anthozoa ) using the 5 ' - end of the 28s rdna . molecular phylogeny and evolution 4 : 175 - 183 .
cappola , v . a . , & fautin , d . g . ( 2000 ) . all three species of ptychodactiaria belong to order actiniaria ( cnidaria : anthozoa ) .
daly , m . , fautin , d . g . , & cappola , v . a . ( 2003 ) . systematics of the hexacorallia ( cnidaria : anthozoa ) .
riemann - zürneck , k . 1969 . sagartia troglodytes ( anthozoa ) biologie und morphologie einer schlick bewohnenden aktinie . veröff . inst . meeresforsch . bremerhaven , 12 : 169–230 .
filkorn hf , allor jp ( 2004 ) a new early cretaceous coral ( anthozoa ; scleractinia ; dendrophylliina ) and its evolutionary significance . j paleont 78 ( 3 ) : 501–512 .
to cite this page : myers , p . and j . burch 2001 .
anthozoa
( on - line ) , animal diversity web . accessed july 09 , 2018 at urltoken
, a new family , new genus and new species of deep - sea zoanthid ( anthozoa : hexacorallia : zoantharia ) from a northwest pacific methane cold seep . invertebr syst 21 : 255–262
berntson ea , france sc , mullineaux ls ( 1999 ) phylogenetic relationships within the class anthozoa ( phylum cnidaria ) based on nuclear 18s rdna sequences . mol phylogen evol 13 : 417–433 .
reimer jd , albinsky d , yang sy , lorion j ( 2014a ) zoanthid ( cnidaria : anthozoa : hexacorallia : zoantharia ) species of coral reefs in palau . mar biodivers 44 : 37–44
a . acosta , m . casas , c . a . vargas , and j . e . camacho , “lista de zoantharia ( cnidaria : anthozoa ) del caribe y de colombia , ”
] included a dense sampling of both anthozoan and medusozoan taxa . however , studies based on mitochondrial dna data suggest that anthozoa is paraphyletic , with octocorals forming a sister group relationship with medusozoans [
zibrowius h , gili jm ( 1990 ) deep - water scleractinia ( cnidaria : anthozoa ) from namibia , south africa , and walvts ridge , southeastern atlantic . sci mar 54 : 19–46 .
fautin , d . g . , and s . l . romano . 2000 . anthozoa . sea nemones , corals , sea pens tree of life web project . retrieved august 2 , 2008 .
chen , c . a . , d . m . odorico , m . ten lohuis , j . e . n . veron , and d . j . miller . 1995 . systematic relationships within the anthozoa ( cnidaria : anthozoa ) using the 5 ' - end of the 28s rdna molecular phylogeny and evolution 4 ( 2 ) : 175–183 . pmid 7663762 . retrieved august 2 , 2008 .
anthozoa is a class of marine invertebrates within the phylum cnidaria that are unique among cnidarians in that they do not do not have a medusa stage in their development . these exclusively polypoid cnidarians are characterized by a tubular body with tentacles around the mouth and most are sedentary after the larval stage . anthozoa includes the sea anemones , corals , sea pens , sea pansies , and sea fans , among others .
reimer jd , ono s , sinniger f , tsukahara j ( 2008b ) distribution of zooxanthellate zoanthid species ( zoantharia : anthozoa : hexacorallia ) in southern japan limited by cold temperatures . galaxea 10 : 57–67
reimer jd , sinniger f , irei y ( 2013c ) preliminary list of macrocnemic zoanthid diversity ( anthozoa : hexacorallia : zoantharia ) from southern shikoku , japan . kuroshio biosphere 9 : 1–x + 2 pls
sinniger f , montoya - burgos ji , chevaldonne p , pawlowski j ( 2005 ) phylogeny of the order zoantharia ( anthozoa , hexacorallia ) based on the mitochondrial ribosomal genes . mar biol 147 : 1121–1128
y . h . fadlallah , r . h . karlson , and k . p . sebens , “a comparative study of sexual reproduction in three species of panamanian zoanthids ( coelenterata : anthozoa ) , ”
f . sinniger , j . i . montoya - burgos , p . chevaldonné , and j . pawlowski , “phylogeny of the order zoantharia ( anthozoa , hexacorallia ) based on the mitochondrial ribosomal genes , ”
t . l . shearer , m . j . h . van oppen , s . l . romano , and g . wörheide , “slow mitochondrial dna sequence evolution in the anthozoa ( cnidaria ) , ”
daly , m . , chaudhuri , a . , gusmão , l . c . , & rodriguez , e . ( 2008 ) . phylogenetic relationships among sea anemones ( cnidaria : anthozoa : actiniaria ) .
scholarspace at university of hawaii at manoa : anatomy and taxonomy of three species of sea anemones ( cnidaria : anthozoa : actiniidae ) from the gulf of california , including isoaulactinia hespervolita daly , n . sp .
j . d . reimer , s . ono , f . sinniger , and j . tsukahara , “distribution of zooxanthellate zoanthid species ( zoantharia : anthozoa : hexacorallia ) in southern japan limited by cold temperatures , ”
data on the ecology and distribution in the estuarine region of the rivers rhine , meuse and scheldt are given for ten species of anthozoa . these data have been correlated with several environmental variables , but especially salinity .
cairns , s . d . , den hartog , j . c . , & arenson , c . ( 1986 ) . anthozoa . in w . sterrer & c . schoepfer - sterrer ( eds . ) ,
england , k . w . ( 1992 ) . certain actiniaria ( cnidaria : anthozoa ) from hong kong with additional data on similar species from aden , bahrain and singapore . in b . morton ( ed . ) ,
unlike the dichotomous anthozoa - medusozoa , our strongly supported finding that anthozoa is paraphyletic further supports the idea that bilateral symmetry , a step of foremost importance in metazoan evolution as it is exhibited as part of most animal body plans ( bauplan ) , was anciently acquired prior to the divergence between cnidaria and bilateria . in fact in cnidaria , increasing evidence supports the presence of bilateral symmetry in corals and sea anemones , where it is represented by the siphonoglyph [
won j , rho b , song j : a phylogenetic study of the anthozoa ( phylum cnidaria ) based on morphological and molecular characters . coral reefs . 2001 , 20 : 39 - 50 . 10 . 1007 / s003380000132 .
( drayton in dana , 1846 ) ( cnidaria : anthozoa : actiniidae ) , an actiniid sea anemone from chile and perú with special fighting tentacles ; with a preliminary revision of the genera with a “frond - like” marginal ruff .
forsman zh , guzman hm , chen ac , fox ge , wellington gm ( 2005 ) an its region phylogeny of siderastrea ( cnidaria : anthozoa ) : is s . glynni endangered or introduced ? coral reefs 24 : 343–347 .
burnett wj , benzie jah , beardmore ja , ryland js ( 1997 ) zoanthids ( anthozoa , hexacorallia ) from the great barrier reef and torres strait , australia : systematics , evolution and a key to species . coral reefs 16 : 55–68
fautin , d . g . ( 2005 ) . three species of intertidal sea anemones ( anthozoa : actiniidae ) from the tropical pacific : description of anthopleura buddemeieri , n . sp . , with remarks on anthopleura asiatica and gyractis sesere .
reimer jd , kim s , arai s , keshavmurthy s , choi k - s ( 2016b ) first records of zooxanthellate zoanthus ( anthozoa : hexacorallia : zoantharia ) from korea and japan ( east ) sea . mar biodiv ( in press )
berntson ea , france sc , mullineaux ls : phylogenetic relationships within the class anthozoa ( phylum cnidaria ) based on nuclear 18s rdna sequences . mol phylogenet evol . 1999 , 13 : 417 - 433 . 10 . 1006 / mpev . 1999 . 0649 .
citation : kitahara mv , cairns sd , stolarski j , blair d , miller dj ( 2010 ) a comprehensive phylogenetic analysis of the scleractinia ( cnidaria , anthozoa ) based on mitochondrial co1 sequence data . plos one 5 ( 7 ) : e11490 . urltoken
daly m . 2004 . anatomy and taxonomy of three species of sea anemones ( cnidaria : anthozoa : actiniidae ) from the gulf of california , including isoaulactinia hespervolita daly , n . sp . . pac sci 58 ( 3 ) : 377 - 390 .
h . fukami , c . a . chen , a . f . budd et al . , “mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not ( order scleractinia , class anthozoa , phylum cnidaria ) , ”
berntson , e . a . , s . c . france , and l . s . mullineaux . 1999 . phylogenetic relationships within the class anthozoa ( phylum cnidaria ) based on nuclear 18s rdna sequences . molecular phylogenetics and evolution 13 : 417 - 433 .
rodríguez , e . , & lópez - gonzález , p . j . ( 2013 ) . new records of antarctic and sub - antarctic sea anemones ( cnidaria , anthozoa , actiniaria and corallimorpharia ) from the weddell sea , antarctic peninsula , and scotia arc .
rodríguez , e . , barbeitos , m . , daly , m . , gusmão , l . c . , & häussermann , v . ( 2012 ) . toward a natural classification : phylogeny of acontiate sea anemones ( cnidaria , anthozoa , actiniaria ) .
france sc , rosel pe , agenbroad je , mullineaux ls , kocher td ( 1996 ) dna sequence variation of mitochondrial large - subunit rdna provides support for a two - subclass organization of the anthozoa ( cnidaria ) . mol mar biol biotechnol 5 : 15–28 .
reimer jd , wee hb , put a jr , hoeksema bw ( 2015 ) zoantharia ( cnidaria : anthozoa : hexacorallia ) of the south china sea and gulf of thailand : species list based on past reports and new photographic records . raffles bull zool 63 : 334–356
citation : aratake s , tomura t , saitoh s , yokokura r , kawanishi y , shinjo r , et al . ( 2012 ) soft coral sarcophyton ( cnidaria : anthozoa : octocorallia ) species diversity and chemotypes . plos one 7 ( 1 ) : e30410 . urltoken
fritzenwanker , j . h . , and technau , u . ( 2002 ) . induction of gametogenesis in the basal cnidarian nematostella vectensis ( anthozoa ) . dev . genes evol . 212 , 99–103 . doi : 10 . 1007 / s00427 - 002 - 0214 - 7
class anthozoa exclusively polypoid with biradial symmetry . oral end a disk with central mouth and hollow tentacles arising at margin and / or on surface . mouth leads to coelenteron via stomodaeum that has ciliated troughs ( siphonoglyphs ) for water transport into and out of coelenteron . coelenteron divided by radial…
kitahara mv , cairns sd , stolarski j , blair d , miller dj : a comprehensive phylogenetic analysis of the scleractinia ( cnidaria , anthozoa ) based on mitochondrial co1 sequence data . plos one . 2010 , 5 : e11490 - 10 . 1371 / journal . pone . 0011490 .
fukami h , knowlton n : analysis of complete mitochondrial dna sequences of three members of the montastraea annularis coral species complex ( cnidaria , anthozoa , scleractinia ) . coral reefs . 2005 , 24 : 410 - 417 . 10 . 1007 / s00338 - 005 - 0023 - 3 .
w . j . burnett , j . a . h . benzie , j . a . beardmore , and j . s . ryland , “zoanthids ( anthozoa , hexacorallia ) from the great barrier reef and torres strait , australia : systematics , evolution and a key to species , ”
france sc , rosel pe , agenbroad je , mullineaux ls , kocher t : dna sequence variation of mitochondrial large - subunit rrna provides support for a two - subclass organization of the anthozoa ( cnidaria ) . mol . mar . biol . biotechnolog . 1996 , 5 : 15 - 28 .
anthozoa ( class ) , bio - eye® hydroxyapatite implant , calcium carbonate matrix , carbonate bone replacement graft ( brg ) , coral carbonate , coral grafts , coral watert , coralline , goniopora species , hydroxyapatite , natural coral , natural coral calcium , nc ( porites ) , sea coral calcite .
wells , j . w . and d . hill . 1956 . anthozoa - general features . pp . f161 - f165 in : r . c . moore ( ed . ) , treatise on invertebrate paleontology part f : coelenterata . geological society of america and university of kansas press , lawrence .
fukami h , chen ca , budd af , collins a , wallace c , et al . ( 2008 ) mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not ( order scleractinia , class anthozoa , phylum cnidaria ) . plos one 3 : e3222 .
brugler mr , france sc : the complete mitochondrial genome of the black coral chrysopathes formosa ( cnidaria : anthozoa : antipatharia ) supports classification of antipatharians within the subclass hexacorallia . mol phylogenet evol . 2007 , 42 : 776 - 788 . 10 . 1016 / j . ympev . 2006 . 08 . 016 .
mcfadden cs , france sc , sánchez ja , alderslade p : a molecular phylogenetic analysis of the octocorallia ( cnidaria : anthozoa ) based on mitochondrial protein - coding sequences . mol phylogenet evol . 2006 , 41 : 513 - 27 . 10 . 1016 / j . ympev . 2006 . 06 . 010 .
reimer j . d . , fujii t . ( 2017 ) zoantharia ( cnidaria : anthozoa : hexacorallia ) diversity research in japan : current state and future trends . in : motokawa m . , kajihara h . ( eds ) species diversity of animals in japan . diversity and commonality in animals . springer , tokyo
with about 6 , 000 species , the class anthozoa includes about two - thirds of extant cnidarian phylum . but unlike other cnidarians , anthozoans do not have a medusa stage in their development . some of species harbor a type of algae ( dinoflagellates called zooxanthellae ) , with which they form a symbiotic relationship . [ 1 ]
brugler mr , france sc : the mitochondrial genome of a deep - sea bamboo coral ( cnidaria , anthozoa , octocorallia , isididae ) : genome structure and putative origins of replication are not conserved among octocorals . j mol evol . 2008 , 67 : 125 - 136 . 10 . 1007 / s00239 - 008 - 9116 - 2 .
summary of the debate ) . anthozoa are traditionally divided into two or three groups , either recognising the black corals and tube anemones , which both have singly occurring mesenteries as a shared feature , as a subclass ( ceriantipatharia ) or demoting them to orders within the zoantharia . the latter scheme ( of hyman , 1940 ) is used here .
the class anthozoa includes a variety of animals that have polyps with a flower - like appearance . in these forms , the gastrovascular cavity is large . it is divided by walls or septa , which arise as folds from the body wall . these folds , along with the mouth and pharynx , are usually arranged in a biradially symmetric pattern .
emblem å , karlsen bo , evertsen j , johansen sd : mitogenome rearrangement in the cold - water scleractinian coral lophelia pertusa ( cnidaria , anthozoa ) involves a long - term evolving group i intron . mol phylogenet evol . 2011 , 61 : 495 - 503 . 10 . 1016 / j . ympev . 2011 . 07 . 012 .
france , s . c . , p . e . rosel , j . e . agenbroad , l . s . mullineaux , and t . d . kocher . 1996 . dna sequence variation of mitochondrial large - subunit rrna provides support for a two subclass organization of the anthozoa ( cnidaria ) . molecular marine biology and biotechnology 5 : 15 - 28 .
] . we also included sequences from two octocoral orders penatulacea and helioporacea , and two hexacoral orders antipatharia and ceriantharia . our analyses suggest that the paraphyly of anthozoa does not result from poor taxon sampling . we also found the groupings [ discomedusae + hydrozoa ] and [ coronatae + [ cubozoa + staurozoa ] ] , contradicting the current rdna - based phylogenetic hypothesis within medusozoa .
though taxonomic classification is a dynamic process , there are currently three recognized cnidaria subphyla . the subphylum medusozoa contains five classes : ( 1 ) hydrozoa , ( 2 ) scyphozoa , ( 3 ) cubozoa , ( 4 ) polypodiozoa , and ( 5 ) staurozoa . species from each class have caused human envenomations . the subphyla anthozoa and myxozoa have also been implicated in envenomation .
theoretically , members of cnidaria have life cycles that alternate between asexual polyps ( the body as a vase shaped form ) , and sexual , free - swimming forms called medusae ( singular medusa ; the body in a bell - shaped form ) . however , members of anthozoa live only as polyps . the anthozoa larva , once fusing with the substratum and developing into the polyp stage , grows benthic or sessile , meaning it no longer metamorphoses into the medusal stage . ( members of scyphozoa live most of their life cycle as medusa , the hydrozoa live as polyps , medusae , and species that alternate between the two , and those of the class cubozoa are named for their cube - shaped medusae , which form the dominant part of their life cycle . )
fautin , d . g . and r . n . mariscal . 1991 . cnidaria : anthozoa . pp . 267 - 358 in f . w . harrison and j . a . westfall ( eds . ) , microscopic anatomy of invertebrates , volume 2 : placozoa , porifera , cnidaria , and ctenophora . wiley - liss , inc . , new york and other cities .
rodríguez , e . , barbeitos , m . , brugler , m . r . , crowley , l . m . , grajales , a . , gusmão , l . c . , et al . ( 2014 ) . hidden among sea anemones : the first comprehensive phylogenetic reconstruction of the order actiniaria ( cnidaria , anthozoa , hexacorallia ) reveals a novel group of hexacorals .
soft corals ( cnidaria : anthozoa : octocorallia ) often equal or exceed the total coverage of scleractinian corals in coral reef ecosystems [ 1 ] – [ 4 ] , and as dominant space - occupiers , important structural components of coral reef communities , and contributors to coral reef biomass [ 4 ] , [ 5 ] , have been the subjects of biological studies since the nineteenth century .
: figure s4 ) . by comparison , under bi we found no support for the validity of anthozoa ( pps = 0 ; bv = 0 ) , acraspeda ( pps = 0 ; bv = 0 ) , scyphozoa ( pps = 0 ; bv = 0 ) , and semaeostomeae ( pps = 0 ; bv = 0 ) in any of our trees under both gtr and catgtr models .
pearson , c . v . , rogers , a . d . , and sheader , m . ( 2002 ) . the genetic structure of the rare lagoonal sea anemone , nematostella vectensis stephenson ( cnidaria ; anthozoa ) in the united kingdom based on rapd analysis . mol . ecol . 11 , 2285–2293 . doi : 10 . 1046 / j . 1365 - 294x . 2002 . 01621 . x
france , s . c . , p . e . rosel , j . e . agenbroad , l . s . mullineaux , and t . d . kocher . 1996 . dna sequence variation of mitochondrial large - subunit rrna provides support for a two subclass organization of the anthozoa ( cnidaria ) molecular marine biology and biotechnology 5 ( 1 ) : 15–28 . pmid 8869515 . retrieved august 2 , 2008 .
scleractinian corals belong to the phylum cnidaria . they form the basis of many tropical reefs ecosystems , but are also abundant in colder waters . there are four classes : hydrozoa ( hydroids ) , scyphozoa ( jellyfishes ) , cubozoa ( sea wasps ) , and anthozoa ( scleractinian corals , corallimorpharians , sea fans , sea anemones , zoanthids and black corals ) , distinguished on the basis of life history and morphology . they are united by certain characteristics : radial symmetry , a central mouth surrounded by tentacles , a single opening through which food is ingested and expelled ( coelenteron ) , a jelly - like middle germ layer ( the mesoglea ) , and intracellular stinging structures called nematocysts . members of the remaining class , anthozoa , exist only as polyps , either solitary or forming colonies ( for a more detailed insight on cnidarian taxonomy , try this link ) .
anthozoa is one of four classes of the invertebrate phylum , the others being hydrozoa ( portuguese man o ' war , obelia , etc . ) , scyphozoa ( true jellyfish ) , and cubozoa ( box jellies ) . all are aquatic and most are marine . the name of the phylum comes from cnidocytes , which are specialized cells that carry stinging secretions that are the cnidarians ' main form of offense or defense and function .
members of most species of anthozoa are suspension feeders , capturing small planktonic invertebrates , phytoplankton , bacteria , and other suspended organic matter ( france 2004 ) . most common are passive methods of capturing prey , when it comes in contact with the tentacles . all cnidarian species can feed by catching prey with nematocysts , with large sea anemones capable of catching fish , crabs , and bivalves , and corals are capable of catching plankton .
the origins of the anthozoa lie in the precambrian , but concrete evidence is sketchy . a number of the vendian , or latest precambrian , soft - bodied
medusoids
are now thought to represent benthic polyp - like organisms . some of the frondlike fossils of the time could represent colonial anthozoans similar to living
sea pens ,
eoporpita is one such vendian fossil that could be a single anthozoan polyp , and charnia is a frondlike fossil that in the past has been linked with
sea pens
or soft corals . however , this issue has not been resolved to everyone ' s satisfaction , although some well - preserved frondlike fossils of the genus charniodiscus from australia may show spicules and individual polyps ( jenkins 1989 ) . in any case , there is molecular evidence to suggest that the anthozoa are the earliest branch of the phylum cnidaria ( bridge et al . 1992 ) .
: figure s3 ) , the other analyses resulting in the near absence of phylogenetic resolution . when some resolution was achieved , the codon analyses yielded similar results to those from the amino acid dataset . we found paraphyletic anthozoa , with medusozoa the sister taxon to octocorallia ( pp > 0 . 95 ) in all codon analyses , but monophyletic cnidaria only in the qmm analysis of the codalim75tx - ser3 dataset ( pp = 0 . 85 , additional file
fukami h , chen ca , budd af , collins a , wallace c , chuang y - y , chen c , dai c - f , iwao k , sheppard c , knowlton n : mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not ( order scleractinia , class anthozoa , phylum cnidaria ) . plos one . 2008 , 3 : e3222 - 10 . 1371 / journal . pone . 0003222 .
] . however , the latter view has only slight phylogenetic support in the currently accepted cnidarian phylogeny , where the most parsimonious scenario involves the gain of the polyp form in the ancestral cnidaria and of the medusa form in medusozoa . alternatively , both the polyp and the medusa forms could have been acquired in the ancestral cnidarian , and the medusa form subsequently lost in the branch leading to anthozoa . the multiple losses of the medusa stage in different medusozoan lineages suggest that this character is indeed evolutionary labile .
) . in addition , gtr - based analyses do not significantly reject the validity of anthozoa ( au = 0 . 63 ; kh = 0 . 41 ; sh = 0 . 93 ) , scyphozoa ( au = 0 . 10 ; kh = 0 . 08 ; sh = 0 . 42 ) , or the clade acraspeda [ cubozoa + scyphozoa ] ( au = 0 . 80 ; kh = 0 . 59 ; sh = 0 . 99 ) , even after removal of the long - branch coronate
fautin , d . g . , crowther , a . l . & wallace , c . c . ( 2008 ) . sea anemones ( cnidaria : anthozoa : actiniaria ) of moreton bay . in davie , p . j . f . & phillips , j . a . ( eds . ) , proceedings of the thirteenth international marine biological workshop , the marine fauna and flora of moreton bay , queensland . memoirs of the queensland museum — nature 54 ( 1 ) : 35–64 . brisbane . issn 0079 - 8835 .
we used an extended dataset of mitochondrial protein genes to reevaluate the phylogeny of cnidaria , paying attention to common biases in phylogenetic reconstructions resulting from insufficient taxon sampling and using more simplistic models of sequence evolution . our phylogenetic analyses suggest the grouping of octocorallia and medusozoa to the exclusion of hexacorallia , resulting in paraphyletic anthozoa . we also recovered the [ discomedusae + hydrozoa ] and [ coronatae + [ cubozoa + staurozoa ] ] relationships within medusozoa . it should be noted , however , that although our data provide little or no support for the clades anthozoa , acraspeda and scyphozoa , they are not rejected with statistically significant support in the maximum - likelihood framework . using the new mito - phylogenomic view , we reconstructed the evolution of several morphological characters in medusozoans . in particular , our phylogenetic hypothesis provided additional evidence for the “polyp first” theory , where the ancestral cnidarian was a bilateral polyp - like organism , and that a radially symmetrical and vagile medusa evolved in the branch leading to medusozoa . our analyses support the view that the ancestor of cnidarians and bilaterians ( ureumetazoa ) possessed bilateral symmetry [
cnidarian mitochondrial genomic data contain phylogenetic signal informative for understanding the evolutionary history of this phylum . mitogenome - based phylogenies , which reject the monophyly of anthozoa , provide further evidence for the polyp - first hypothesis . by rejecting the traditional acraspeda and scyphozoa hypotheses , these analyses suggest that the shared morphological characters in these groups are plesiomorphies , originated in the branch leading to medusozoa . the expansion of mitogenomic data along with improvements in phylogenetic inference methods and use of additional nuclear markers will further enhance our understanding of the phylogenetic relationships and character evolution within cnidaria .
the phylogenetic relationships within the anthozoa were re - evaluated based on 41 morphological characters and nuclear sequences of 18s ribosomal dna ( 29 anthozoans as ingroups and 3 hydrozoans as outgroups ) . the parsimony trees derived from the morphological data did not coincide closely with the molecular data , and the presence of several polytomies at some nodes of the trees resulted in ambiguities among the systematic relationships . on the other hand , the combined analysis using total evidence presents a more resolved and highly supported topology , as is indicated by higher bootstrap values and decay indices than either analysis alone . however , strict and semi - strict consensus trees derived from taxonomic congruence show a poorer resolution for the phylogeny of anthozoa . the trees constructed from the molecular data , using neighbor - joining and maximum - likelihood methods , are nearly congruent with the result from the total evidence . based on these results , anthozoa is divided into three subclasses : alcyonaria , zoantharia , and ceriantipatharia . the ceriantipatharia now includes only one order , ceriantharia , since the order antipatharia is more closely related to orders within the zoantharia . the alcyonaria is a monophyletic group , in which the order pennatulacea is basal , and orders alcyonacea and telestacea branch later . the order gorgonacea is divided into two suborders , holaxonia and scleraxonia . bellonela is more related to order stolonifera , forming a monophyletic group . in zoantharia , the order zoanthinaria is basal , and the remaining taxa are divided into two clades : one includes the order actiniaria and the other includes orders antipatharia , corallimorpharia , and scleractinia . the latter two orders form a monophyletic group . this study presents a different phylogeny of actiniarians from the earlier hypothesis of scleractinian ancestry .
the class anthozoa also includes many kinds of corals , including many reef - building species . reefs are formed by the calcareous skeletons of many generations of coral polyps . the polyps inhabit only the surface of the reefs . these reefs are among the most productive environments of the world , housing thousands of species of fish and invertebrates , not to mention plants and protists . like some anemones , many corals are inhabited by symbiotic algae called zooxanthellae . these photosynthetic algae are essential for those coral , which generally do not live at depths to which light does not penetrate .
class anthozoa is traditionally considered to have two or three subclasses . hyman ( 1940 ) divided the class into alcyonaria and zoantharia , based largely on polyp symmetry and tentacle form and number . wells and hill ( 1956 ) recognized a third subclass , ceriantipatharia ( listed also by dunn 1982 ) , based on similarity of the ceriantharian larval stage to the antipatharian polyp , on the very weak mesentery musculature in both groups , and on the insertion of new mesenterial couples only in the dorsal intermesenterial space of members of both orders . evidence from morphology ( hand 1966 ) , nematocysts ( hand 1966 , schmidt 1974 ) , and dna ( france et al . 1996 , song and won 1997 , berntson et al . 1999 ) does not support the monophyly of the ceriantharia and antipatharia . indeed , hand ( 1966 ) suggested division of anthozoa into four subclasses ( antipatharia , ceriantharia , zoantharia , and alcyonaria ) could be justified . while the most complete molecular data available ( berntson et al . 1999 ) do not support the monophyly of the ceriantharia and antipatharia , placement of the ceriantharia remains uncertain . the ceriantharia may merit subclass status but more data are necessary to determine its phylogenetic position ( berntson et al . 1999 ) .
we expanded the sampling of cnidarian mitochondrial genomes , particularly from medusozoa , to reevaluate phylogenetic relationships within cnidaria . our phylogenetic analyses based on a mitochogenomic dataset support many prior hypotheses , including monophyly of hexacorallia , octocorallia , medusozoa , cubozoa , staurozoa , hydrozoa , carybdeida , chirodropida , and hydroidolina , but reject the monophyly of anthozoa , indicating that the octocorallia + medusozoa relationship is not the result of sampling bias , as proposed earlier . further , our analyses contradict scyphozoa [ discomedusae + coronatae ] , acraspeda [ cubozoa + scyphozoa ] , as well as the hypothesis that staurozoa is the sister group to all the other medusozoans .
: figure s5 ) suggests that compositional bias is also an unlikely explanation . the amino acid composition of hexacorallia is rather divergent , but not similar to those of the two outgroups ( porifera and placozoa ) ; in fact , the composition similarity between octocorallia and the outgroups would favor the alternative possibility of anthozoa paraphyly [ medusozoa + hexacorallia ] , which is not observed in our analyses . to further test the possible impact of compositional bias , we analyzed our alignments using the catgtr model with a dayhoff recoding strategy , despite the fact that it implies a loss of signal resulting in increasing the stochastic error . interestingly , octocorallia remained sister - group of medusozoa , even if the statistical support was reduced ( data not shown ) .
cnidaria ( corals , sea anemones , hydroids , jellyfish ) is a phylum of relatively simple aquatic animals characterized by the presence of the cnidocyst : a cell containing a giant capsular organelle with an eversible tubule ( cnida ) . species within cnidaria have life cycles that involve one or both of the two distinct body forms , a typically benthic polyp , which may or may not be colonial , and a typically pelagic mostly solitary medusa . the currently accepted taxonomic scheme subdivides cnidaria into two main assemblages : anthozoa ( hexacorallia + octocorallia ) – cnidarians with a reproductive polyp and the absence of a medusa stage – and medusozoa ( cubozoa , hydrozoa , scyphozoa , staurozoa ) – cnidarians that usually possess a reproductive medusa stage . hypothesized relationships among these taxa greatly impact interpretations of cnidarian character evolution .
anthozoans have two mainly related structures , the actinopharynx and the mesenteries , which are unique among cnidarian polyps . the actinopharynx , or stomodeum , is a tubular gullet extending all the way from mouth to the coelenteron . the actinopharynx of most species contains at least one siphonoglyph , flagellated longitudinal channel , that drives water into the coelenteron . most of corals and sea anemones have two siphonoglyphs situated directly opposite on one another in the actinopharynx . siphonoglyphs and their associated structures make the polyps bilateral or a biradial symmetry . [ 4 ] mesenteries , longitudinal sheets of tissue , increase surface area for respiration and especially for absorption of food , they also provide support . perhaps because mesenteries increase , some polyps of anthozoa can grow much larger than any other polyps in other class of cnidaria . [ 5 ]
in 1913 carglren , who was probably the most active researcher on this order , said “among the anthozoa ( … ) there is hardly a group which is so uniform in its morphological characteristics as the zoantharia …” [ 23 ] . nearly a hundred years later , despite numerous taxonomical investigations of the morphological characteristics of this order , carlgren ' s statement is still accurate . the sphincter position has been traditionally used to identify zoanthid genera , although lwowsky [ 24 ] illustrated the risks of misidentification using this character . this is exemplified in the parazoanthidae , in which recent taxonomic work casts doubts on the significance of the sphincter muscle position ( the main distinguishing feature of isozoanthus ) as a valid character [ 7 ] and recent studies based on morphology assigned various unrelated zoanthids to the genus isozoanthus [ 25 ] – [ 28 ] , none of which matched with the ecological characteristics of previously described isozoanthus species . similarly , swain [ 29 ] showed clearly that the sphincter position did not allow proper identification at the genus level and does not represent the evolutionary history of this group .
cnidarians comprise four classes of toxic marine animals : anthozoa , cubozoa , scyphozoa and hydrozoa . they are the largest and probably the oldest phylum of toxic marine animals . any contact with a cnidarian , especially the box jellyfish ( chironex fleckeri ) , can be fatal , but most cnidarians do not possess sufficiently strong venomous apparatus to penetrate the human skin , whereas others rarely come into contact with human beings . only a small , almost negligible percentage of the vast wealth of cnidarian toxins has been studied in detail . many polypeptide cnidarian toxins are immunogenic , and cross - reactivity between several jellyfish venoms has been reported . cnidarians also possess components of innate immunity , and some of those components have been preserved in evolution . on the other hand , cnidarian toxins have already been used for the design of immunotoxins to treat cancer , whereas other cnidarian toxins can modulate the immune system in mammals , including man . this review will focus on a short overview of cnidarian toxins , on the innate immunity of cnidarians , and on the mode of action of cnidarian toxins which can modulate the immune system in mammals . emphasis is palced on those toxins which block voltage activated potassium channels in the cells of the immune system .
one of the most common groups of organisms on the reefs of florida and the greater caribbean is the zoanthids . in fact , some zoanthids ( anthozoa : hexacorallia ) are so common that a portion of the shallow intertidal zone has been called the “ zoanthus zone” [ 7 ] . like many reef - building hard corals , most shallow tropical and subtropical zoanthids are in symbiosis with symbiodinium ( = zooxanthellae ) species , endosymbiotic , photosynthetic dinoflagellates . despite being an obvious and ubiquitous part of the caribbean coral reef ecosystem , the taxonomy and diversity of zoanthids worldwide are poorly understood , and even species identification remains problematic [ 8 – 10 ] . however , recent research utilizing different mitochondrial and nuclear dna markers has allowed researchers to begin to reassess zoanthid species identification [ 9 , 10 ] . in this study , we apply these molecular methods to investigate the diversity of shallow water zoanthids in florida . phylogenetic species or species groups were then compared with original species descriptions in an attempt to formally identify specimens . our results ( 1 ) demonstrate the utility of molecular methods in zoanthid identification , ( 2 ) indicate that previously undescribed zoanthid diversity may be common in the caribbean sea despite overall diversity being likely lower than in the taxonomic literature , and ( 3 ) highlight the considerable taxonomic problems of shallow water brachycnemic zoanthids in the caribbean sea .
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cambrian - age localities with soft - bodied organisms preserved also include some soft - bodied sea anemones and
sea pens ,
such as mackenzia and thaumaptilon from the burgess shale and xianguangia from the chengjiang biota of china . a few of the cambrian
small shelly fossils
are spicules  nearly microscopic , mineralized , needle - like pieces  that appear similar to the spicules of living octocorals ( bengtson et al . 1990 ) .
a few mineralized corals and coral - like organisms also appeared as early as the lower cambrian ( e . g . , sorauf and savarese 1995 ; tynan 1983 ) . a minor group of corals , the cothoniida , is known from the middle cambrian . however , it was not until the ordovician that mineralized corals became important parts of marine ecosystems . by the middle of the ordovician , several lineages of corals had become distinct : the tabulata , the rugosa , and the smaller heliolitida . the best - known rugose corals are the
horn corals ,
solitary polyps , usually with a conical or horn - like shape , that are abundant at many paleozoic localities ( such as the large middle devonian fossil heliophyllum pictured at the top of this page ) . however , all three groups of corals could and did form massive reefs . heliolitids went extinct in the late devonian , at the time of a mass extinction event that also impacted the rugosa and , to a lesser extent , the tabulata . however , these two groups soon recovered and flourished until the end of the permian .
both tabulate and rugose corals disappeared in the permo - triassic mass extinction about 245 million years ago . in the middle
. the scleractinia do not appear to be close relatives of either the tabulata or the rugosa , and probably evolved from sea anemone - like ancestors that have not been preserved as fossils . like earlier corals , the scleractinians soon evolved massive colonial species that formed great reefs . the image above shows an early scleractinian reef , now a massive limestone layer preserved in dunlap canyon , nevada , near the town of mina . ( note the person standing on top for scale . ) colonial scleractinians have continued to dominate most tropical reef habitats since the triassic , while other scleractinians live as solitary polyps in a wide range of habitats .
the fossil record of octocorals is sparse . as mentioned , there are some cambrian fossils that indicate their presence . there are also a few paleozoic fossil
sea pens
and
sea fans
( e . g . , bengtson 1981 ; glinski 1956 ) . however , most of the known fossil octocorals are cretaceous and cenozoic in age ( e . g . , deflandre - rigauld 1956 ; kocurko 1993 ) . fossil octocorals may be more common than is usually suspected , but probably go unrecognized when found .
bengtson , s . 1981 . atractosella , a silurian alcyonacean octocoral . journal of paleontology 55 : 281 - 294 .
bengtson , s . , s . conway morris , b . j . cooper , p . a . jell , and b . n . runnegar . 1990 . early cambrian fossils from south australia . memoirs of the association of australasian palaeontologists 9 : 1 - 364 .
bridge , d . , c . w . cunningham , b . schierwater , r . desalle , and l . w . buss . 1992 . class - level relationships in the phylum cnidaria : evidence from mitochondrial gene structure . proceedings of the national academy of sciences of the usa 89 : 8750 - 8753 .
conway morris , s . 1993 . ediacaran - like fossils in cambrian burgess shale - type faunas of north america . palaeontology 36 : 593 - 635 .
deflandre - rigaud , m . 1956 . les sclèrites d ' alcyonaires fossiles . élèments d ' une classification . annales de palèontologie 42 ( 4 ) : 1 - 24 .
glinski , a . 1956 . plumalina conservata n . sp . ( gorgonaria ) aus dem mittel - devon der eifel . senckenbergiana lethaea 37 : 53 - 57 .
jenkins , r . j . f . 1989 . the
supposed terminal precambrian extinction event
in relation to the cnidaria . memoirs of the association of australasian palaeontologists 8 : 307 - 317 .
kocurko , m . j . 1993 . eunicella sp . , octocorallia from the red bluff formation , lower oligocene , mississippi . tulane studies in geology and paleontology 26 : 35 - 40 .
sorauf , j . e . , and m . savarese . 1995 . a lower cambrian coral from south australia . palaeontology 38 : 757 - 770 .
tynan , m . g . 1983 . coral - like microfossils from the lower cambrian of california . journal of paleontology 57 : 1188 - 1211 .
greek , ippos = horse + greek , kampe = curvature ( ref . 45335 )
marine ; reef - associated ; non - migratory ; depth range 16 - 40 m ( ref . 30915 ) . tropical ; 3°n - 23°s
indo - west pacific : japan to queensland , australia eastward to vanuatu . conservation status : data deficient ( ref . 30915 ) . international trade is monitored through a licensing system ( cites ii , since 5 . 15 . 04 ) .
maturity : l m 1 . 3 range ? - ? cm max length : 2 . 4 cm ot male / unsexed ; ( ref . 31803 )
dorsal spines ( total ) : 0 ; dorsal soft rays ( total ) : 13 - 15 . description based on 4 specimens : adult height , less than 2 . 0 cm . rings , 11 - 12 + 31 - 34 . snout length is greater than 4 . 0 in head length . dorsal fin rays , 13 - 15 covering 1 + 1 rings . pectoral fin rays , 10 . coronet , a rounded knob . spine , as irregular bulbous tubercles scattered over body and tail ; a single prominent rounded eye spine ; a single low rounded cheek spine . other distinctive characters : head and body very fleshy , mostly without recognizable body rings ; ventral portion of trunk segments incomplete ; snout extremely short . color pattern : two color morphs are known : ( a ) pale grey or purple with pink or red tubercles ( found on gorgonian coral muricella plectana ) and ( b ) yellow with orange tubercles ( found on gorgonian coral muricella paraplectana ) .
only known to occur on gorgonian corals of the genus muricella , with up to 28 pairs on a single gorgonian . the tubercles and truncated snout of this species match the color and shape of the polyps of the host gorgonian , while its body matches the gorgonian stem . so extreme is this camouflage that the original specimens were only noticed after their host gorgonian had been collected and observed in an aquarium . post - pelagic young settle on various hosts , but to breed , they appear to prefer the red polyp muricella spp . that usually grow in depths over 20 m ( ref . 48635 ) . ovoviviparous ( ref . 205 ) . the male carries the eggs in a brood pouch which is found under the tail ( ref . 205 ) .
possibly monogamous in the wild ( ref . 30915 ) . male carries the eggs in a brood pouch ( ref . 205 ) .
lourie , s . a . , a . c . j . vincent and h . j . hall , 1999 . seahorses : an identification guide to the world ' s species and their conservation . project seahorse , london . 214 p . ( ref . 30915 )
) : 25 . 9 - 29 , mean 27 . 7 ( based on 134 cells ) .
phylogenetic diversity index ( ref . 82805 ) : pd 50 = 0 . 5000 [ uniqueness , from 0 . 5 = low to 2 . 0 = high ] .
bayesian length - weight : a = 0 . 00427 ( 0 . 00164 - 0 . 01111 ) , b = 3 . 00 ( 2 . 78 - 3 . 22 ) , in cm total length , based on lwr estimates for this ( sub ) family - body shape ( ref . 93245 ) .
trophic level ( ref . 69278 ) : 3 . 4 ±0 . 5 se ; based on size and trophs of closest relatives
resilience ( ref . 69278 ) : high , minimum population doubling time less than 15 months ( fec = 34 ) .
vulnerability ( ref . 59153 ) : low vulnerability ( 10 of 100 ) .
knowledge of scleractinian coral reproduction has expanded greatly over the past 10 years into one of most intensely studied aspects of coral biology . review by richmond and hunter ( 1990 ) provides overview of status of knowledge . reproductive data are now available for about 210 of approx . 600 spp . of reef corals . what is most impressive is the variety and versatility of coral reproduction ( according to region , varies even within same species ) and can be both sexual and asexual ( veron , 2000 ) . the individual coral polyp can be male , female , both or may not be reproductively active at all . if a polyp is just of one sex then it is termed gonochoric . a polyp that is both male and female is known as a hermaphrodite . egg and sperm production can occur on the same mesentery or on differentiated mesenteries in same polyp , in different polyps of same colony , or at different times in same colony ( i . e . sequential as well as simultaneous hermaphroditism ) .
: corals are immobile organisms with separate sexes ( 25 % of all known species ; veron , 2000 ) . they rely on precise timing in order to bring their gametes together . species which spawn must release their gametes into the water simultaneously . this is done in response to environmental cues , sexual reproduction offers two opportunities for new genetic combinations to occur :
b ) the genetic contribution of two different parents when an egg is fertilized by a sperm .
to prevent self - fertilization , male and female gametes in hermaphroditic corals never mature at the same time .
broadcasters ( spawners ) : in hermatypic corals , spawners outnumber brooders ; about 75 % of all known coral species spawn positively buoyant gametes ( eggs and sperm ) at very specific times so as to ensure fertilization ( veron , 2000 ) . broadcasting is typical of corals in buttress and forereef zones of massive colonial forms with indeterminate growth ; broadcasters have high larval mortality but successful recruits can invade new environments with lower competition with surviving colonies that can live 100s of years . fertilization is external at the water surface . many coral species mass spawn ; i . e . within a 24 hour period , all the corals from one species and often within a genus release their eggs and sperm at the same time ; e . g . montastraea , montipora , platygra , galaxea , favia , and favites ( wallace , 1994 ) . intraspecies fertilization is common but mass spawning raises the possibility of hybridization by congeneric species ( wallace , 1994 - breaking with the dogma of species as a biological unit ) . the zygote develops into a larvae ( called planulae ) which attaches itself to a suitable substrate , metamorphoses to a founder polyp , and grows into a new colony . brooders : most ahermatypic corals are brooders as are hermatypes living in disturbed , nearshore reef zones . likewise , species in zones with high adult mortality , have high competition for spaces , and are exposed to intense bioerosion , require high rates of recruitment . in this strategy , sperm , but never eggs , are released into the water . brooding produces mature , often negatively buoyant planulae ready to settle ; ( e . g . favia fragum broods embryos for 3 weeks ; brooding also found in goniopora , diaseris , and agaricia ) . asexually brooded planulae larvae may be developed by a kind of budding ; i . e . internal fertilization , brooding of zygote , and release of a positively buoyant planulae . the larvae float to the top , sink back , settle , and metamorphose into a founder polyp , to become later on another colony . species of acropora release brooded larvae ( vivipary ) .