Premnas biaculeatusMaroon clownfish(Also: spinedcheek anemonefish)

Ge­o­graphic Range

Spinecheek anemone­fish, Prem­nas bi­ac­ulea­tus, are found in the Indo-West Pa­cific, in­clud­ing the coasts of India, Burma, Thai­land, Malaysia, In­done­sia, Philip­pines, New Guinea, New Britain, Solomon Is­lands, Van­u­atu and north­ern Queens­land. (Ca­puli and San­tos, 2006)

Habi­tat

The most im­por­tant as­pect of spinecheek anemone­fish habi­tat is the host anemone. En­tac­maea quadri­color, bulb-ten­ta­cle sea anemones, are the only host species for spinecheek anemone­fish. This anemone species is char­ac­ter­ized by polyps 50 to 400 mm in di­am­e­ter, de­pend­ing on depth. They have brown ten­ta­cles of about 100 mm long with a red tip and white bulb at the end of the ten­ta­cle. Spinecheek anemone­fish tend to live mainly in soli­tary spec­i­mens of En­tac­maea quadri­color on reef slopes. The typ­i­cal water depth is less than 50 m, be­cause anemones re­quire sun­light to grow. The mu­tu­al­is­tic zoox­an­thel­lae (liv­ing within the anemone) need this sun­light to pho­to­syn­the­size and pro­vide en­ergy for them­selves and the anemone. These anemone pre­fer trop­i­cal warm wa­ters with the tem­per­a­ture rang­ing be­tween 25 and 28°C (77-82°F). (Fautin and Allen, 1992)

  • Range depth
    50 (high) m
    164.04 (high) ft

Phys­i­cal De­scrip­tion

Spinecheek anemone­fish are among the eas­i­est anemone­fish to iden­tify, even when young. They are bright red with 3 bars that are bright white in males and grey in fe­males. In­di­vid­u­als may be­come bright white if they are pro­voked. The lines may also be bright yel­low. (Fautin and Allen, 1992)

  • Sexual Dimorphism
  • female larger
  • male more colorful
  • Range length
    <60 to 160 mm
    to 6.30 in
  • Average length
    70 mm
    2.76 in

De­vel­op­ment

The de­vel­op­men­tal stages of spinecheek anemone­fish are egg, lar­vae, young and adult. The trans­par­ent, el­lip­ti­cal eggs are 3-4 mm in size. Anemone­fish hatch with ad­vanced al­i­men­tary canals and feed on the yolk, which usu­ally lasts for about 3 days. Five days after hatch­ing they de­velop supranu­clear in­clu­sions around the hindgut, which sug­gests pinocy­totic di­ges­tion of pro­tein. Be­tween 3 to 5 days after hatch­ing is the pe­riod of high­est mor­tal­ity stage for anemone­fish if they can­not find food. It is also the time when they tran­si­tion from en­doge­nous to ex­oge­nous feed­ing. Seven days after hatch­ing they at­tain gas­tric glands and by the 9th day they have supranu­clear vac­uoles that in­di­cate ex­oge­nous di­ges­tive ca­pa­bil­i­ties. Spinecheek anemone­fish hatch 6 to 7 days after fer­til­iza­tion, and then un­dergo a 7 to 14 day pelagic lar­val stage. After fer­til­iza­tion, they com­plete the de­vel­op­ment of the ol­fac­tory organ in 19 days, reti­nal dif­fer­en­ti­a­tion in 20 days and skele­tal os­si­fi­ca­tion in about 22 days. Spinecheek anemone­fish de­velop more rapidly than other anemone­fish species. Their eyes de­velop es­pe­cialy rapidly. Vi­sion is di­rectly cor­re­lated with the abil­ity to at­tain food be­cause most lar­val fish are vi­sual feed­ers. Ol­fac­tory cues are used to de­tect host anemones. Dur­ing the lar­val stage spinecheek anemone­fish live on the water sur­face where they are trans­ported by cur­rents. (Cough­lin, 1994; Gor­don and Hecht, 2002; Job and Bell­wood, 1996; Ka­vanagh and Al­ford, 2003)

Meta­mor­pho­sis oc­curs when anemone­fish leave sur­face wa­ters and swim to the sea bot­tom. It then takes on the color pat­tern of a ju­ve­nile. This process usu­ally takes about one day. This marks the be­gin­ning of the set­tle­ment pe­riod, in which in­di­vid­u­als seek out an un­in­hab­ited anemone host. (Cough­lin, 1994; Gor­don and Hecht, 2002; Job and Bell­wood, 1996; Ka­vanagh and Al­ford, 2003)

Spinecheek anemone­fish, like other anemone­fish species, are protan­drous her­maph­ro­dites, which means that they change from male to fe­male. Fe­males have go­nads that func­tion as ovaries with left­over male tes­tic­u­lar tis­sue. In the case of spinecheek anemone­fish, males may be half the size of fe­males and their go­nads have dor­mant ovar­ian cells as well as func­tion­ing testes. (Fautin and Allen, 1992)

Re­pro­duc­tion

Spinecheek anemone­fish have a monog­a­mous mat­ing sys­tem and mated pairs may stay to­gether for sev­eral years. The dom­i­nant fe­male is the largest and has one part­ner, which is the next largest male within a clus­ter of anemones. The growth of other anemone­fish in the same anemone patch is stunted by the pres­ence of a dom­i­nant male and fe­male, keep­ing them smaller than the dom­i­nant male. When one or the other of the dom­i­nant in­di­vid­u­als dies, sub­or­di­nates grow and re­place the dead in­di­vid­ual. For ex­am­ple, if the dom­i­nant male dies, the next largest male will re­place him and con­tinue to grow to its max­i­mum size. (Fautin and Allen, 1992)

Males, be­fore spawn­ing, go through an ex­ten­sive rit­ual of courtship that con­sists of dis­play­ing the dor­sal, anal and pelvic fins. He also chases and nips his mate. (Fautin and Allen, 1992)

Spinecheek anemone­fish may spawn through­out the year in trop­i­cal areas. In cooler water they may spawn dur­ing the warm sea­son. (Fautin and Allen, 1992)

  • Breeding interval
    Breeding may occur throughout the year, depending on water temperature.
  • Breeding season
    In the tropics spawning occurs year-round; those in temperate and subtropical waters spawn when the temperatures are highest in summer and spring.
  • Range number of offspring
    100 to 1000
  • Range time to hatching
    6 to 7 days
  • Range time to independence
    8 to 12 days

Males care pri­mar­ily for the eggs. Be­fore spawn­ing, males find and pre­pare a nest for the eggs. He cleans the area by re­mov­ing the de­bris and algae from the area. Usu­ally the fe­male ends up join­ing in the task. Dur­ing in­cu­ba­tion the male guards and cares for the nest. He chases away any pos­si­ble preda­tors that may want to feast on the eggs, such as wrasses. Male anemone­fish use their pec­toral fins to fan the eggs and spend time metic­u­lously re­mov­ing dead eggs and de­bris from the nest with their mouths. Fe­males will oc­ca­sion­ally as­sist males but mainly spend their time feed­ing. (Fautin and Allen, 1992)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male

Lifes­pan/Longevity

The lifes­pan of spinecheek anemone­fish has not been well re­searched. They live longer in the wild, rang­ing from 6 to 10 years, and about 3 to 5 years in cap­tiv­ity under good con­di­tions. A re­lated species, Am­phiprion perid­eraion, was recorded liv­ing to 18 years. (Fautin and Allen, 1992; Kramer, 2005)

  • Typical lifespan
    Status: wild
    6 to 10 years
  • Typical lifespan
    Status: captivity
    3 to 5 years

Be­hav­ior

Spinecheek anemone­fish have a so­cial hi­er­ar­chy in which fish that oc­cupy the same patch of anemones are or­dered in sta­tus by size. Gen­er­ally there is a breed­ing pair and then 0 to 4 non-breed­ers. The largest is the fe­male of the group (high­est rank), fol­lowed by the largest male, who is part of the breed­ing pair. In the case of the death of the fe­male, the sec­ond largest changes from male to fe­male. Size dif­fer­ence is main­tained in order to avoid sub­or­di­nates be­com­ing a threat to the high­est rank­ing male. There is an av­er­age dif­fer­ence of 10 mm be­tween ranks in the re­lated anemone­fish, Am­phiprion per­cula. When a dom­i­nant anemone­fish dies, the next sub­or­di­nate moves up in the rank order and grows fur­ther. (Bus­ton, 2003)

Spinecheek anemone­fish are ac­tive dur­ing the day. Once they set­tle onto an anemone as a ju­ve­nile, and then adult, they re­main in the same area through­out their life.

Home Range

Spinecheek anemone­fish are ter­ri­to­r­ial, de­fend­ing the area around their host anemone. Usu­ally one anemone hosts the breed­ing pair and 4 to 5 other non-breed­ing males. (Bus­ton, 2003; Fautin and Allen, 1992)

Com­mu­ni­ca­tion and Per­cep­tion

Mates com­mu­ni­cate in courtship through move­ment and touch. Dur­ing spawn­ing, fe­males swim in a zig-zag pat­tern over the nest while the male fer­til­izes the eggs. Males also “shows off” their fins to fe­males, a form of vi­sual com­mu­ni­ca­tion. (Fautin and Allen, 1992; Fautin and Allen, 1992)

Food Habits

Spinecheek anemone­fish have a diet rich in cope­pods and plank­tonic, lar­val tu­ni­cates. They also eat other kinds of plank­ton and algae. (Fautin and Allen, 1992)

  • Primary Diet
  • carnivore
    • eats non-insect arthropods
    • eats other marine invertebrates
  • Animal Foods
  • aquatic or marine worms
  • aquatic crustaceans
  • other marine invertebrates
  • zooplankton

Pre­da­tion

The most vul­ner­a­ble stage for spinecheek anemone­fish is dur­ing the egg and lar­val stage, when they are not pro­tected by a host anemone and float freely in the water col­umn. As set­tled adults, En­tac­maea quadri­color pro­tects these sym­bi­otic fish be­cause of their abil­ity to de­liver a ven­omous sting. Wrasses are known to prey on eggs and other fish are likely preda­tors of eggs, lar­vae, and un­set­tled ju­ve­niles. (Cough­lin, 1994; Fautin and Allen, 1992)

  • Known Predators
    • wrasses (Labridae)
    • other fish predators

Ecosys­tem Roles

Spinecheek anemone­fish and their host anemones have a mu­tu­al­ist re­la­tion­ship. En­tac­maea quadri­color ben­e­fits from hav­ing spinecheek anemone­fish pro­tect them from but­ter­fly­fish (Chaetodon­ti­dae), which would oth­er­wise eat their ten­ta­cles. Spinecheek anemone­fish also clean away de­bris and par­a­sites from the anemone. Spinecheek anemone­fish are pro­tected from most preda­tors through their as­so­ci­a­tion with ven­omous anemones.

Mu­tu­al­ist Species
  • bub­ble tip anemones (En­tac­maea quadri­color)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Spinecheek anemone­fish are im­por­tant to the aquar­ium sup­pli­ers who sell them for profit. These anemone­fish, and their rel­a­tives, are im­por­tant eco­tourist draws for div­ing op­er­a­tions. Their sym­bi­otic re­la­tion­ship with En­tac­maea quadri­color, helps to pro­tect these anemones.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of the spinecheek anemone­fish on hu­mans.

Con­ser­va­tion Sta­tus

Al­though spinecheek anemone­fish are not en­dan­gered, there are con­cerns for pop­u­la­tions and their reef habi­tats due to the "Nemo craze". In the last gen­er­a­tion 15 to 30% of the world's reefs have been lost. After re­lease of Dis­ney's "Find­ing Nemo" movie, which has an anemone­fish as its main pro­tag­o­nist, anemone­fish sales have in­creased. Col­lect­ing meth­ods are often ex­tremely de­struc­tive, per­ma­nently dam­ag­ing reefs. (Os­ter­houdt, 2004)

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Jo­hanna Higuera (au­thor), Uni­ver­sity of Notre Dame, Karen Pow­ers (ed­i­tor, in­struc­tor), Rad­ford Uni­ver­sity.

Glossary

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

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.

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

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.

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

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.

phytoplankton

photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)

protandrous

condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products

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.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

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

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

zooplankton

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

Ref­er­ences

Co­lum­bia Uni­ver­sity Press. 2000. "Life on the Reef: The Amaz­ing World of Coral Fishes" (On-line). The Na­tional His­tory Mu­seum. Ac­cessed April 11, 2006 at http://​www.​fathom.​com/​course/​2170172/​session1.​html.

Bus­ton, P. 2003. Size and growth mod­i­fi­ca­tion in clown­fish. Na­ture, 424: 145-146. Ac­cessed April 11, 2006 at www.​nature.​com/​nature.

Ca­puli, E., C. San­tos. 2006. "Prem­nas bi­ac­ulea­tus" (On-line). Fish­Base. Ac­cessed April 11, 2006 at http://​fishbase.​org/​summary/​speciessummary.​php?​id=6632.

Cough­lin, D. 1994. Suc­tion Prey Cap­ture by Clown­fish Lar­vae (Am­phiprion perid­eraion). Copeia, 1: 242-246.

Fautin, D., D. Allen. 1992. Field Guide to Anemone Fishes and their Host Sea Anemones. Perth, WA 6000 Aus­tralia: West­ern Aus­tralian Mu­seum. Ac­cessed April 11, 2006 at http://​www.​nhm.​ku.​edu/​inverts/​ebooks/​intro.​html.

Gor­don, A., T. Hecht. 2002. His­to­log­i­cal stud­ies on the de­vel­op­ment of the di­ges­tive sys­tem of the clown­fish Am­phiprion per­cula and the time of wean­ing. J. Appl. Ichthyol., 18: 113-117. Ac­cessed April 11, 2006 at www.​blackwell.​de/​synergy.

Job, S., D. Bell­wood. 1996. Vi­sual acu­ity and feed­ing in lar­val Prem­nas bi­ac­ulea­tus. Jour­nal of Fish Bi­ol­ogy, 48: 952-963.

Ka­vanagh, K., R. Al­ford. 2003. Sen­sory and skele­tal de­vel­op­ment and growth in re­la­tion to the du­ra­tion of the em­bry­onic and lar­val stages in dam­selfishes. Bi­o­log­i­cal Jour­nal of the Lin­nean So­ci­ety, 80: 187-206.

Kramer, S. 2005. "An Ex­plo­ration of the Clown­fish" (On-line). Tree of Life Web Pro­ject. Ac­cessed April 11, 2006 at http://​tolweb.​org/​treehouses/?​treehouse_​id=3390.

Os­ter­houdt, S. 2004. Buy­ing Nemo. E Mag­a­zine, July/Au­gust: 10.

Wikipedia.​com, 2006. "Ma­roon Clown­fish" (On-line). Wikipedia.​com. Ac­cessed April 11, 2006 at http://​en.​wikipedia.​org/​wiki/​Maroon_​Clownfish.