Amphiprion Tricinctus

The three-band anemonefish (''Amphiprion tricinctus'') is a species of anemonefish endemic to the Marshall Islands in the western part of the Pacific Ocean. Like all anemonefishes, it forms a symbiotic mutualism with sea anemones and is unaffected by the stinging tentacles of its host. It is a sequential hermaphrodite with a strict size-based dominance hierarchy; the female is largest, the breeding male is second largest, and the male nonbreeders get progressively smaller as the hierarchy descends. They exhibit protandry, meaning the breeding male changes to female if the sole breeding female dies, with the largest nonbreeder becoming the breeding male. The fish's natural diet includes zooplankton.

Description

The body of ''A. tricinctus'' is yellow-orange at the snout, belly, and pelvic and anal fins, tending to dark brown or black at the tail. As the common name suggests, as an adult it has three white bands or bars. They can grow to be about long

Color variations

As ''A. tricinctus'' is endemic to the Marshall Islands, no geographic variation is seen, bute variations to the proportions of orange and black occur, from predominately orange through to predominantly black and the occasional aberrant coloration. Fish living with the host anemone'' Stichodactyla mertensii'', Mertens' carpet sea anemone, are frequently black except for the snout and bars.

Similar species

Two other species have three body bars and a dark tail, ''A. chrysogaster'' and ''A. fuscocaudatus'', but the species are geographically separated.
Three other species of anemonefish are found in the Marshall Islands, ''A. chrysopterus'', ''A. melanopus'', and ''A. perideraion''. These are easily distinguished from ''A. tricinctus'' as ''A. chrysopterus'' has two body bars and a whitish caudal fin, ''A. melanopus'' only has a head bar, and ''A. perideraion'' has a distinctive white stripe on the dorsal ridge. Genetic analysis has shown that ''A. tricinctus'' is closely related to ''A. clarkii'' and this clade is significantly different from the other species traditionally considered part of the ''A. clarkii ''complex.

Distribution and habitat

''A. tricinctus'' is endemic to the Marshall Islands in the western part of the Pacific Ocean and is found in lagoons and pinnacle and seaward reefs. Whilst it is most commonly found at depths of , it is occasionally found hosted by solitary specimens of '' Entacmaea quadricolor'' on seaward reef slopes in excess of deep.

Host anemones

The relationship between anemonefish and their host sea anemones is not random and instead is highly nested in structure. ''A. tricinctus'' is highly generalised, being hosted by eight of the 9 host anemones found in the Marshall Islands. ''A. tricinctus'' is generally said to be associated with these species of anemone:

*'' Entacmaea quadricolor'' bubble-tip anemone
*'' Heteractis aurora'' beaded sea anemone (mostly juvenile)
*'' Heteractis crispa'' sebae anemone
*'' Stichodactyla haddoni''
*'' Stichodactyla mertensii'' Mertens' carpet sea anemone

Many locations in the Marshall Islands have not been scientifically surveyed, and ''A. tricinctus'' has been reported to be hosted by these species of anemone:
*'' Heteractis magnifica'' magnificent sea anemone (rarely)
*'' Heteractis malu'' delicate sea anemone (rarely)
*'' Macrodactyla doreensis'' long-tentacle anemone

Conservation status

Anemonefish and their host anemones are found on coral reefs and face similar environmental issues. Like corals, anemone's contain intracellular endosymbionts, zooxanthellae, and can suffer from bleaching due to triggers such as increased water temperature or acidification. Characteristics known to elevate the risk of extinction are small geographic range, small local population, and extreme habitat specialisation. ''A. tricinctus'' is an endemic species, confined to the Marshall Islands, and this species' ability to use a variety of anemone hosts is thought to reduce the risk of extinction associated with specialisation.

In the aquarium

Specimens of ''A. tricinctus'' are occasionally for sale and the species has been bred in captivity.

Notes

References

External links

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{{Taxonbar, from=Q304249

Amphiprion
Fish described in 1953