Animal Diversity Web

Ge­o­graphic Range

Am­phiprion akin­dynos, also known as the Bar­rier Reef anemone­fish or clown­fish, is na­tive to the West­ern Pa­cific. Am­phiprion akin­dynos is pri­mar­ily found in the wa­ters of the Great Bar­rier Reef of Aus­tralia and in the ad­ja­cent Coral Sea. It has also been found in wa­ters off of north­ern New South Wales, New Cale­do­nia, sec­tions of the In­dian Ocean and around the Loy­alty Is­lands. There is some ques­tion as to whether A. akin­dynos also in­hab­its the wa­ters around Sri Lanka. (Ran­dall, et al., 1990)

• Biogeographic Regions
• indian ocean
  • native
• pacific ocean
  • native

Habi­tat

Am­phiprion akin­dynos in­hab­its reef wa­ters and la­goons be­tween 1 and 25 me­ters deep with tem­per­a­tures rang­ing from 10 to 32 de­grees Cel­sius. They are found in na­ture swim­ming in and closely around the ten­ta­cles of their host anemone. They are able to live and make shel­ter among the ten­ta­cles of anemones with­out being harmed by the ne­ma­to­cysts (sting­ing cells) pre­sent on the anemone’s ten­ta­cles. Ac­cord­ing to Allen (1980), A. akin­dynos are pro­tected from pos­si­ble stings by a spe­cial sub­stance which is pre­sent in their ex­ter­nal mu­cous cov­er­ing. This sub­stance does not ac­tu­ally pro­tect them from the sting­ing cells. “In­stead, it low­ers the thresh­old of ne­ma­to­cyst dis­charge. In other words, it pre­vents the sting­ing cells from fir­ing.” Host species of anemone for A. akin­dynos are: En­tac­maea quadri­color, Het­er­ac­tis au­rora, H. crispa, H. mag­nifica, Sti­chodactyla had­doni, and S. merten­sii. (Allen, 1980; Allen, 1991; Fautin and Allen, 1992; Froese and Pauly, 2002; Ran­dall, et al., 1990)

• Habitat Regions
• tropical
• saltwater or marine

• Aquatic Biomes
• reef

• Range depth

  1 to 25 m

  3.28 to 82.02 ft

Phys­i­cal De­scrip­tion

The body and head of adult A. akin­dynos are both a brown­ish or­ange color. Two black-edged white bars en­cir­cle the body. The first bar runs across the top of the head just be­hind the eye and can be dis­con­tin­u­ous and con­stricted (thin). The sec­ond stripe runs around the body at the mid por­tion of the dor­sal fin. The cau­dal pe­dun­cle and cau­dal fin are both white. Am­phiprion akin­dynos in­di­vid­u­als have 10 to 11 dor­sal spines, 14 to 17 dor­sal soft rays, 2 anal spines, and 13 to 14 soft anal rays.

Ju­ve­niles are usu­ally brown with three thick white bars. Sub-adults are usu­ally yel­low with two thin white bars. Both adults and ju­ve­niles and are often con­fused with A. clarkii and A. chrysopterus. How­ever, A. clarkii have a more dis­tinct color dif­fer­ence be­tween their body and tail than adult A. akin­dynos and A. chrysopterus tend to have a darker or­ange color with bluish bars. (Allen, 1991; Fautin and Allen, 1992; Froese and Pauly, 2002)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Average mass

  27.5 g

  0.97 oz

• Range length

  45 to 130 mm

  1.77 to 5.12 in

• Average length

  90 mm

  3.54 in

De­vel­op­ment

The lar­val pe­riod of A. akin­dynos ranges from about 8 to 12 days. Al­though not known for cer­tain, many be­lieve that dur­ing this pe­riod the lar­vae are plank­tonic, “liv­ing in the sur­face wa­ters of the ocean, where they are pas­sively trans­ported by cur­rents” (Fautin and Allen, 1992). At the end of this pe­riod, the fish will de­scend to the bot­tom of the sea and begin to ac­quire the color pat­terns as­so­ci­ated with ju­ve­niles. Once they get to the bot­tom, the young will begin to search for a host anemone. With­out the pro­tec­tion of the anemone there is a high like­li­hood that a fish will be eaten by its preda­tors and there is ev­i­dence that there is a high mor­tal­ity rate at this stage of de­vel­op­ment (Fautin and Allen, 1992).

Arved­lund et. al. (2000) have found ev­i­dence that A. akin­dynos im­print onto their host anemone dur­ing their lar­val stage and are able to fol­low a trail of chem­i­cals re­leased by this host anemone, thus al­low­ing these fish to re­turn to the same species of host anemone to live and spawn. How­ever, once re­turn­ing to their host anemone a fish can­not sim­ply swim into the anemone be­cause it may get stung. Ac­cord­ing to Fautin and Allen (1992) it can take sev­eral hours to be­come fully ac­cli­mated to the anemone once it is lo­cated. The ac­cli­ma­tion process con­sists of a se­ries of pro­gres­sively longer con­tacts with the ten­ta­cles. A. akin­dynos are ini­tially pro­tected from ne­ma­to­cyst stings by a thick mucus coat. How­ever, over the ac­cli­ma­tion process, the clown­fish in­cor­po­rates anemone mucus into its own coat until the anemone no longer stings it, ap­par­ently rec­og­niz­ing the fish as part of it­self.

Even once a fish lo­cates a host anemone it is not guar­an­teed a place to live. Within the anemone, there is an in­tri­cate so­cial hi­er­ar­chy. All A. akin­dynos begin life as males. Within a given anemone, the largest fish is the fe­male and the next largest fish is her mate. There can be sev­eral other males in this struc­ture; how­ever, they gen­er­ally do not have much chance of mat­ing. If the fe­male dies, the next largest male will be­come a fe­male and the sec­ond largest male will be­come the new mate. In this struc­ture the fe­male is the dom­i­nant fish and her mate is the sec­ond most dom­i­nate. The re­main­der of the fish must com­pete and fight for a place in the anemone.

(Fautin and Allen, 1992; Arved­lund et al., 2000) (Fautin and Allen, 1992)

Re­pro­duc­tion

Mated pairs oc­cupy the same anemone. Sev­eral days prior to spawn­ing, there is in­creased so­cial in­ter­ac­tion be­tween A. akin­dynos males and fe­males. Usu­ally the male be­comes more ag­gres­sive and will pur­sue and bite his mate. He also dis­plays him­self ei­ther in front of his mate or be­side her by fully ex­tend­ing his dor­sal, anal, and pelvic fins. Dur­ing this time, the male also se­lects a nest site, usu­ally on bare rock ad­ja­cent to the host anemone. The male will spend con­sid­er­able time clear­ing the site of algae and de­bris using his mouth. Some­times the fe­male will join in. Spawn­ing usu­ally oc­curs dur­ing the morn­ing hours and can last from about 30 min­utes to more than two hours. The fe­male will swim in a zig-zag path over the nest with her belly brush­ing its sur­face. This brush­ing causes sev­eral eggs from her ovipos­i­tor to be dis­lodged. The male will fol­low be­hind the fe­male and fer­til­ize the eggs as they are laid. This will con­tinue until all eggs have been dis­lodged. (Arved­lund, et al., June 2000; Fautin and Allen, 1992; Froese and Pauly, 2002; Richard­son, et al., 1997)

• Mating System
• monogamous

The num­ber of eggs de­posited can range from about 100 to over 1000, de­pend­ing on the size of the fish and on pre­vi­ous ex­pe­ri­ence. The eggs are el­lip­ti­cal and are about 3 to 4 mm in length. They ad­here to the nest sur­face by a tuft of short fil­a­ments. The eggs will in­cu­bate six to seven days be­fore hatch­ing. (Arved­lund, et al., June 2000; Fautin and Allen, 1992; Froese and Pauly, 2002; Richard­son, et al., 1997)

Bar­rier reef anemone­fish are her­maph­ro­ditic, with young de­vel­op­ing into males first and only later into fe­males if con­di­tions are ap­pro­pri­ate.

• Key Reproductive Features
• iteroparous
• year-round breeding
• sequential hermaphrodite
  • protandrous
• sexual
• fertilization
  • external
• oviparous

• Breeding interval

  Breeding intervals in the wild are unknown.

• Breeding season

  Breeding may occur throughout the year.

• Range number of offspring

  100 to 1000

• Range time to hatching

  6 to 7 days

Bar­rier Reef anemone­fish are nesters. Males guard the nest from preda­tors and fan the nest with the pec­toral fins to re­move de­bris. (Arved­lund, et al., June 2000; Fautin and Allen, 1992; Froese and Pauly, 2002; Richard­son, et al., 1997)

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

Lifes­pan/Longevity

In­di­vid­u­als gen­er­ally live be­tween 6 and 10 years in the wild. How­ever, as noted ear­lier, there is a high mor­tal­ity rate dur­ing the lar­val, fry, and ju­ve­nile stages, which cor­re­spond to life stages when the fish do not nec­es­sar­ily have the pro­tec­tion of a host anemone.

They have been known to live up to 18 years in cap­tiv­ity. (Fautin and Allen, 1992; Froese and Pauly, 2002)

• Range lifespan
  Status: captivity

  18 (high) years

• Typical lifespan
  Status: wild

  6 to 10 years

Be­hav­ior

As noted be­fore, Am­phiprion akin­dynos has a very in­ter­est­ing so­cial struc­ture. There is a sin­gle dom­i­nant fe­male in each so­cial group who is the largest of all the fish in­hab­it­ing an anemone. She has a sin­gle male mate who is the sec­ond largest fish. Be­tween two and four other smaller males can also live in the anemone. There is gen­er­ally an am­i­ca­ble re­la­tion­ship be­tween the fe­male and her mate, and any ag­gres­sion by the fe­male is dis­played as rit­u­al­ized, non-harm­ful be­hav­iors. How­ever, ag­gres­sion is more pro­nounced be­tween the all of the males. There is a dis­tinct peck­ing order where the largest male spends time chas­ing and bul­ly­ing the next largest male, who in turn bul­lies the smaller fishes. At­tacks may be so se­vere as to drive away the small­est fish (gen­er­ally the newest mem­ber of the hi­er­ar­chy) who must find an­other anemone to live in or die. Again, as noted be­fore, when the fe­male dies, the largest male will as­sume her po­si­tion. Al­most im­me­di­ately after she is gone, the largest male will begin dis­play­ing be­hav­iors sim­i­lar to the pre­vi­ous fe­male. Within days the male will ac­tu­ally change sexes and be­come fe­male and the next largest male will be­come the mate. (Fautin and Allen, 1992; Carver, 2002)

• Key Behaviors
• natatorial
• motile
• territorial
• dominance hierarchies

Com­mu­ni­ca­tion and Per­cep­tion

Bar­rier Reef anemone­fish use vi­sual cues to com­mu­ni­cate among them­selves. Chem­i­cal com­mu­ni­ca­tion via their pro­tec­tive mu­cous cov­er­ing is es­sen­tial to their sym­bio­sis with anemones.

• Communication Channels
• visual
• chemical

• Perception Channels
• visual
• tactile
• chemical

Food Habits

Bar­rier Reef anemone­fish pri­mar­ily eat algae and zoo­plank­ton. Cope­pods and lar­val tu­ni­cates are among the most com­mon items found when their stom­ach con­tents are an­a­lyzed. The adult pair of fish (the fe­male and her mate) are the largest fish in the so­cial hi­er­ar­chy. They tend to stray fur­ther from the host anemone to gather food than do the smaller non-dom­i­nate fish. It is spec­u­lated that one rea­son for the rapid growth of the mate and the sec­ond dom­i­nate male when the fe­male dies is that the fish can spend more time feed­ing and less time com­pet­ing for a place to live. (Fautin and Allen, 1992; Froese and Pauly, 2002)

• Primary Diet
• carnivore
  • eats non-insect arthropods
• planktivore

• Animal Foods
• aquatic or marine worms
• aquatic crustaceans
• echinoderms
• cnidarians
• other marine invertebrates
• zooplankton

• Plant Foods
• phytoplankton

Pre­da­tion

Am­phiprion akin­dynos avoid being preyed on by other larger fish by stay­ing in and around their host anemone. As de­scribed above, they have a sub­stance in the mu­cous cov­er­ing their bod­ies, mak­ing it pos­si­ble for them to touch the ten­ta­cles and not get stung. Preda­tors will avoid get­ting stung by the ten­ta­cles of the host anemone and thus A. akin­dynos will be safe from larger fish. They may oc­ca­sion­ally be preyed on when they are away from a host anemone, ei­ther as ju­ve­niles look­ing for a host, or when ejected from their host ter­ri­tory by an­other anemone­fish. (Allen, 1980)

• Known Predators

  • larger fish (Actinopterygii)

Ecosys­tem Roles

Am­phiprion akin­dynos have a mu­tu­al­is­tic sym­bi­otic re­la­tion­ship with their host anemones. This arrange­ment works for both Am­phiprion akin­dynos and their host. With­out the anemone’s pro­tec­tion and shel­ter, Am­phiprion akin­dynos are quickly con­sumed. Con­versely Am­phiprion akin­dynos fight off in­trud­ers, such as anemone-eat­ing but­ter­fly­fish that would oth­er­wise prey on the anemone. Ad­di­tion­ally there may be some ben­e­fit to the anemone from the fishes’ feed­ing. Bits of food may drop onto the host and help feed it. It has also been sug­gested that the fish as­sists in keep­ing the anemone clean. The fish mov­ing in and out of the anemone helps to cre­ate cur­rents of water, which as­sist bring­ing food to the anemone and also in keep­ing it free of de­bris. (Allen, 1980; Fautin and Allen, 1992; Froese and Pauly, 2002; Ran­dall, et al., 1990)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Am­phiprion akin­dynos is pop­u­lar in the aquar­ium trade and is an im­por­tant mem­ber of the ecosys­tems in which they live. They con­tribute to the color and in­ter­est of reef ecosys­tems, thereby at­tract­ing tourism. Am­phiprion species are im­por­tant as re­search or­gan­isms in un­der­stand­ing mu­tu­al­ism.

• Positive Impacts
• pet trade
• ecotourism
• research and education

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no neg­a­tive af­fects of anemone­fish on hu­mans.

Con­ser­va­tion Sta­tus

Bar­rier Reef anemone­fish are not listed as en­dan­gered on any in­ter­na­tional data­base.

• IUCN Red List

  No special status

• US Federal List

  No special status

• CITES

  No special status

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Amelia Wenk (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Allen, G. 1991. Dam­selfishes of the World. Melle, Ger­many: Mer­gus Pub­lish­ers.

Allen, G. 1972. The Anemone Fishes: Their Clas­si­fi­ca­tion and Bi­ol­ogy, 2nd Edi­tion. Nep­tune City, New Jer­sey: T. F. H. Pub­li­ca­tions Inc..

Allen, G. 1980. The Anemone­fishes of the World: Species, Care and Breed­ing. United States: Aquar­ium Sys­tems.

Arved­lund, M., I. Bundgaard, L. Nielsen. June 2000. Host Im­print­ing in Anemone­fishes (Pisces: Po­ma­cen­tri­dae): Does it Dic­tate Spawn­ing Site Pref­er­ences?. En­vi­ron­men­tal Bi­ol­ogy of Fishes, 58(2): 203-213.

Carver, L. "PBS Evo­lu­tion Se­ries" (On-line). Ac­cessed Oc­to­ber 20, 2002 at http://​www.​pbs.​org/​wgbh/​evolution.

Fautin, D., G. Allen. 1992. Field guide to anemone-fishes and their host sea anemones, 1st ed.. Perth, Aus­tralia: West­ern Aus­tralian Mu­seum.

Froese, R., D. Pauly. 2002. "Fish­base" (On-line). Ac­cessed Oc­to­ber 9, 2002 at www.​fishbase.​org.

Ran­dall, J., G. Allen, R. Steene. 1990. Fishes of the Great Bar­rier Reef and Coral Sea.. Hon­olulu, Hawaii: Uni­ver­sity of Hawaii Press.

Richard­son, D., P. Har­ri­son, V. Har­riot. 1997. Tim­ing of spawn­ing and fe­cun­dity of a trop­i­cal and sub­trop­i­cal anemone­fish (Po­ma­cen­tri­dae: Am­phiprion) on a high lat­i­tude reef on the east coast of Aus­tralia.. Ma­rine Ecol­ogy Progress Se­ries, 156: 175-181.