Gorgonia ventalinaCommon sea fan

Ge­o­graphic Range

The ge­o­graphic range of Gor­gonia ven­talina is from Bermuda to Cu­ra­cao, in­clud­ing the Florida Keys and West­ern Caribbean. How­ever, it is not found in the Gulf of Mex­ico. In ge­o­graphic ranges, it is found in the south­east­ern part of the of the nearc­tic re­gion and the north­west­ern part of the neotrop­i­cal re­gion. (Colin, 1978)

Habi­tat

Gor­gonia ven­talina is dis­trib­uted in a clumped, non-ran­dom dis­tri­b­u­tion on coral reefs. Usu­ally the most com­mon gor­gon­ian in coral reef habi­tats, it is pri­mar­ily found on band and patch reefs. In ad­di­tion, the G. ven­talina can be found in near-shore areas with heavy wave ac­tion and also on deeper reefs (depths greater than 15 m). (Colin, 1978)

Phys­i­cal De­scrip­tion

Gor­gonia ven­talina is usu­ally pur­ple but can vary to its less com­mon col­ors of yel­low-or­ange, yel­low, and brown. In some cases, the color of the sea fan is a re­sult of the en­vi­ron­ment and the chem­i­cals in the en­vi­ro­ment. The prin­ci­ple pig­ments of the sea fan are fixed in the spicules (nee­dle-like parts of solid cal­cium car­bon­ate). Col­ors re­sult from chem­i­cal pig­ments pro­duced in the spicules. Since the color of the fan varies, the shape of the spicules is the only pos­i­tive iden­ti­fier of G. ven­talina. The spicules are small and fusiform. The polyps of the G. ven­talina pro­trude from the spicules as tiny frag­ile white flow­ers. It is these in­di­vid­ual polyps that form the sea fan.

Gor­gonia ven­talina can be up to 180 cm tall and 150 cm wide, with anas­to­mose branches, which form uni­pla­nar, retic­u­late, fan-shaped colonies. The branches are round or slightly com­pressed in the plane of the fan branch. (Colin, 1978; Kester, 1900; Ster­rer, 1986)

  • Range length
    180 (high) cm
    70.87 (high) in

De­vel­op­ment

Once a plan­u­lae polyp is set­tled on a hard sur­face, the young polyp cre­ates a hori­zona­tal layer of arag­o­nite called the basal disk. As the polyp grows up­ward, the base's mar­gin also turns up­ward, form­ing a cup called the ep­itheca, which con­tains daily growth bands. These and other sturctures called septa form the skele­tal bound­aries found at the bot­tom of the coral polyps, which are left be­hind as a re­sult of the up­ward growth of the polyp. (Cary, May 15, 1915; Druf­fel, Au­gust 5, 1997)

Re­pro­duc­tion

Gor­gon­ian corals re­pro­duce asex­u­ally by cloning or frag­men­ta­tion, with ex­ter­nal fer­til­iza­tion. The lar­vae typ­i­cally spend sev­eral days as plank­ton be­fore set­tling on a hard sur­face to begin for­ma­tion of a colony. (Druf­fel, Au­gust 5, 1997; Gotelli, April 1991)

  • Parental Investment
  • no parental involvement

Lifes­pan/Longevity

There are sev­eral po­ten­tial causes of death for G. ven­talina. The great­est cause of mor­tal­ity is the dis­at­tach­ment of a colony from the sub­strate, most likely by wave ac­tion and storms. The over­growth of the sea fan by other or­gan­isms is also an­other lead­ing cause of death, es­pe­cially by the hy­dro­co­ralline Mil­li­pora al­ci­cor­nis and some en­crust­ing bry­ozoa. The cause of death is at­trib­uted to the lack of food and oxy­gen to the polyp. Re­cently, mor­tal­ity has also been at­trib­uted to tumor growth. The tu­mors ob­served on G. ven­talina ex­posed to en­vi­ron­men­tal stresses in­clude the pres­ence of pol­lu­tants, ris­ing water tem­per­a­ture, in­creased nu­tri­ent con­cen­tra­tions, and in­creased tur­bid­ity. The large tumor masses, which were most often con­cen­trated at the axial bases of the af­fected clonies were clearly as­so­ci­ated with tis­sue death (necro­sis) and ero­sion of the af­fected coral. Ac­cord­ing to Cary, there is no ev­i­dence that gor­gon­ian colonies ever die from old age. (Cary, May 15, 1915; Morse, et al., 1977)

Be­hav­ior

Gor­gonia ven­talina will ori­ent ac­cord­ing so that the "fan" is per­pen­dic­u­lar to the mo­tion of the waves. This ori­en­ta­tion only oc­curs in the adult sea fans. The young will grow in any di­rec­tion, but as they ma­ture will slowly shift until they are fac­ing the cur­rent. (Grigg, March 1972)

Com­mu­ni­ca­tion and Per­cep­tion

In An­tho­zoans, spe­cial­ized sen­sory or­gans are ab­sent and nerves are arranged in nerve nets. Most nerve cells allow im­pulses to travel in ei­ther di­rec­tion. Hair­like pro­jec­tions on in­di­vid­ual cells are mechanore­cep­tors and pos­si­ble chemore­cep­tors. Some An­tho­zoans show a sen­si­tiv­ity to light. (Br­usca and Br­usca, 2003)

Food Habits

Gor­gonia ven­talina is car­nivourous, feed­ing on zoo­plank­ton, es­pe­cially at night. A pas­sive feeder, Gor­gonia ven­talina ori­ents it­self in the path of the sea cur­rent, so that the cur­rent flows past the fan and the zoo­plank­ton in the cur­rent are caught and eaten. In ad­di­tion to being a car­niv­o­rous pas­sive feeder, G. ven­talina also has zoox­an­thel­lae, which ex­ten­sively col­o­nize the sea fan, es­pe­cially in the epi­der­mis, polyps, and gas­tro­der­mal canals and the an­thoco­dial sep­tae. These zoox­an­thel­lae, usu­ally Sym­bio­dinium sp., are also able to pro­vide the sea fan with nu­tri­ents through its pho­to­syn­thetic ac­tiv­i­ties. (Morse, et al., 1977)

Pre­da­tion

Gor­gonia ven­talina con­tains sec­ondary metabo­lites and cal­ci­fied scle­rites that act as anti-preda­tor de­fenses. These anti-preda­tor de­fenses act as suc­cess­ful feed­ing de­ter­rents to the Cyphoma gib­bo­sum, a com­mon preda­tor of the G. ven­talina. Cyphoma gib­bo­sum feeds on gor­gon­ian polyps by crawl­ing slowly over the skele­ton. Tro­to­nia ham­nero­rum is a spe­cial­ized preda­tor on G. ven­talina. (Cronin, et al., March 1995; Van Al­styne and Paul, Sep­tem­ber 1992)

  • Known Predators

Ecosys­tem Roles

Gor­gonia ven­talina has sev­eral ecosys­tem roles, pri­mar­ily by serv­ing as a sub­strate for many other or­gan­isms. For ex­am­ple, bi­vavle mol­luscs, sponges, and algae may grow on dead sec­tions of the sea fan. How­ever, it is not known if the growth of these or­gan­isms kills the sec­tions or if they in­vade after the coral is al­ready dead. Cer­tain or­gan­isms, such as the brit­tle star and the bas­ket starfish, use the tall G. ven­talina to climb to a more ad­van­ta­geous po­si­tion for fil­ter feed­ing in reef areas. There have been stud­ies into the role that sea fans, in­clud­ing G. ven­talina, have in the for­ma­tion of coral reefs. Con­clu­sions were the lime­stone inner struc­ture pro­vides some of the base where other corals may at­tach to form more colonies. (Cary, May 15, 1915; Colin, 1978)

  • Ecosystem Impact
  • creates habitat
Mu­tu­al­ist Species
  • Sym­bio­dinium sp.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Com­pounds have been sep­a­rated from G. ven­talina to make an­tibi­otics. These com­pounds in­clude oc­ta­co­ral.

Gor­gonia ven­talina is pop­u­larly col­lected for use in aqau­ri­ums and as sou­venirs.

As a col­or­ful ad­di­tion to coral reef habi­tats, its pres­ence also is im­por­tant to eco­tourism. (Morse, et al., 1977)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Could not find any ad­verse ef­fects on hu­mans.

Con­ser­va­tion Sta­tus

No cur­rent con­ser­va­tion de­tails avail­able.

Con­trib­u­tors

Renee Sher­man Mul­crone (ed­i­tor).

Lee Goetz (au­thor), Hood Col­lege, Mau­reen Foley (ed­i­tor), Hood Col­lege.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

asexual

reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

planktivore

an animal that mainly eats plankton

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sessile

non-motile; permanently attached at the base.

Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

Ref­er­ences

Ben­nett, I. 1974. The Great Bar­rier Reef. New York: Scrib­ner.

Br­usca, R., G. Br­usca. 2003. In­ver­te­brates. Sun­der­land, Mass­a­chu­setts: Sin­auer As­so­ci­ates, Inc..

Cary, L. May 15, 1915. The Al­cy­onaria as a fac­tor in reef lime­stone for­ma­tion. Pro­ceed­ings of the Na­tional Acad­emy of Sci­ences of the United States of Amer­ica, 1, (5): 285-289.

Colin, P. 1978. Caribbean Reef In­ver­te­brates and Plants. Nep­tune City, NJ: TFH Pub­li­ca­tions.

Cronin, G., M. Hay, W. Fini­cal, N. Lindquist. March 1995. Dis­tri­b­u­tion, den­sity, and se­ques­tra­tion of host chem­i­cal de­fenses by the spe­cial­ist nudi­branch *Tri­to­nia ham­nero­rum* found at high den­si­ties on the sea fan *G. ven­talina*. Ma­rine Ecol­ogy - Progress Se­ries, 119 (1-3): 177-189.

Druf­fel, E. Au­gust 5, 1997. Geo­chem­istry of corals: prox­ies of past ocean chem­istry, ocean cir­cu­la­tion, and cli­mate. Proc. Natl. Acad. Sci USA, Vol. 94, No. 16: 8354-8361.

Gotelli, N. April 1991. De­mo­graphic mod­els for *Lep­to­gor­gia vir­gu­lata*, a shal­low-wa­ter gor­gon­ian. Ecol­ogy, 72 (2): 457-467.

Grigg, R. March 1972. Ori­en­ta­tion and growth form of sea fans. Lim­nol­ogy and Oceanog­ra­phy, 17(2): 185 - 192.

Guthrie, M., J. An­der­son. 1961. Gen­eral Zo­ol­ogy. New York: John Wiley & Sons.

Kester, E. 1900. A Trea­tise on Zo­ol­ogy Part II. Lon­don: Adam and Charles Black.

Longhurst, A., D. Pauly. Ecol­ogy of Trop­i­cal Oceans.

Morse, D., A. Morse, H. Dun­can. 1977. Algal tu­mors in the Caribbean sea fan *G. ven­talina*. 3rd In­ter­na­tional Coral Reef Sym­po­sium Pro­ceed­ings.

Ster­rer, W. 1986. Ma­rine Flora and Fauna of Bermuda. New York: Wiley.

Van Al­styne, K., V. Paul. Sep­tem­ber 1992. Chem­i­cal and struc­tural de­fenses in the sea fan *G. ven­talina* - ef­fects against gen­er­al­ist and spe­cial­ist preda­tors. Coral Reefs, 11 (3): 155-159.