''Amphiprion chagosensis'', the Chagos anemonefish, is a marine fish belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Pomacentridae Pomacentridae is a family of ray-finned fish, comprising the damselfishes and clownfishes. This family were formerly placed in the order Perciformes or as indeterminate percomorphs, but are now considered basal blenniiforms. They are primaril ...

, the

clownfish Clownfishes or anemonefishes (genus ''Amphiprion'') are saltwater fishes found in the warm and tropical waters of the Indo-Pacific. They inhabit mainly coral reefs and have a distinctive colouration typically consisting of white vertical bars on ...

es and

damselfish Damselfish are those fish within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastinae within the family Pomacentridae. Most species within this group are relatively small, although the four largest speci ...

es. It is named for the

Chagos Archipelago The Chagos Archipelago (, ) or Chagos Islands (formerly , and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about south of the Maldives archipelago. This chain of islands is the southernmo ...

in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

and it is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the archipelago. The original specimens were collected at

Diego Garcia Diego Garcia is the largest island of the Chagos Archipelago. It has been used as a joint UK–U.S. military base since the 1970s, following the expulsion of the Chagossians by the UK government. The Chagos Islands are set to become a former B ...

Atoll, Chagos Archipelago.

Characteristics of anemonefish

Clownfish or anemonefish are

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

es that, in the wild, form

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

mutualisms with

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

s and are unaffected by the stinging tentacles of the host anemone, see . The sea anemone protects the clownfish from predators, as well as providing food through the scraps left from the anemone's meals and occasional dead anemone tentacles. In return, the clownfish defends the anemone from its predators, and parasites. Clownfish are small-sized, , and depending on species, they are overall yellow, orange, or a reddish or blackish color, and many show white bars or patches. Within species, there may be color variations, most commonly according to distribution, but also based on sex, age and host anemone. Clownfish are found in warmer waters of the Indian and

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

oceans and the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

in sheltered

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

s or in shallow

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...

s. In a group of clownfish, there is a strict

dominance hierarchy In the zoological field of ethology, a dominance hierarchy (formerly and colloquially called a pecking order) is a type of social hierarchy that arises when members of animal social animal, social groups interact, creating a ranking system. Dif ...

. The largest and most aggressive fish is female and is found at the top. Only two clownfish, a male and a female, in a group reproduce through

external fertilization External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. It is contrasted with internal fertilization, in which sperm are introduced via insemination and then ...

. Clownfish are sequential hermaphrodites, meaning that they develop into males first, and when they mature, they become females.

Description

Adults are light brown with two white bars with dark edging encircling the body. All fins are dusky brown. They have 10-11 dorsal spines, 2 anal spines, 15-17 dorsal soft rays and 13-14 anal soft rays. They reach a maximum length of .

Color variations

None known.

Similar species

The Chagos anemonefish is mainly distinguished by location, with similar species mostly having a geographic separation, with '' A. akindynos'' being found on the

Great Barrier Reef The Great Barrier Reef is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching for over over an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland, ...

and

Coral Sea The Coral Sea () is a marginal sea of the Pacific Ocean, South Pacific off the northeast coast of Australia, and classified as an Interim Biogeographic Regionalisation for Australia, interim Australian bioregion. The Coral Sea extends down t ...

and '' A. allardi'' in

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

. '' A. bicinctus'' is found in the

but has an overlapping distribution at Chagos. ''A. chagosensis'' has a narrower headbar and a whiteish caudal fin. Specimens can also be distinguished by differences in predorsal scalation. Image:A, chagosensis 2.jpg, ''A. chagosensis'', with Macrodactyla doreensis, long tentacle anemone Image:Amphiprion akindynos RLS.jpg, '' A. akindynos'' (Barrier Reef anemonefish) Image:Amphiprion allardi in the UShaka Sea World 1038.jpg, '' A. allardi'' (Allard's anemonefish). Image:Amphiprion bicinctus by Patryk Krzyzak.jpg, '' A. bicinctus'' (Two-band anemonefish)

Distribution and habitat

''A. chagosensis'' is found only in the Chagos Archipelago.

Host anemones

Little is known about the specific host anemone species with which ''A. chagosensis'' associates, however it has been photographed in association with: *'' Entacmaea quadricolor'' Bubble-tip anemone *'' Heteractis magnifica'' magnificent sea anemone *'' Macrodactyla doreensis'' long tentacle anemone *'' Stichodactyla mertensii'' Mertens' carpet sea anemone

References

External links

* * {{Taxonbar, from=Q1058817 chagosensis Chagos Archipelago Fish described in 1972 Taxa named by Gerald R. Allen