The Spot-tailed Butterflyfish, ''Chaetodon ocellicaudus'', is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, a

butterflyfish The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. The approximately 129 species in 12 genera are found mostly on the reefs of the Atla ...

belonging to the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Chaetodontidae. It is found in the central Indo- west Pacific region from

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

, north to the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

and

Palau Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the ...

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, and ...

. It grows to a maximum of long. Nearly identical to the Black-backed Butterflyfish (''C. melannotus''), it differs only in the shape of the black mark on the

caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

, in lacking a black mark on the chest, a lighter back, and in having an average of 14 rather than 15

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

rays. ''C. ocellicaudus'' belongs to the large subgenus ''Rabdophorus'' which might warrant recognition as a distinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

. In this group, it appears to be a close relative of the Black-backed Butterflyfish and somewhat less close to the Yellow-dotted Butterflyfish (''C. selene''). These are all of oval shape, silvery with yellow fins and snout, ascending diagonal stripes, and black markings around the eyes, on the

, and sometimes on the back. Next closest seem the

Saddle Butterflyfish The saddle butterflyfish (''Chaetodon ephippium'') is a species of marine ray-finned fish, a butterflyfish belonging to the family Chaetodontidae. It is found in the Indian and Pacific Oceans from Sri Lanka and the Cocos-Keeling Islands to the ...

(''C. ephippium'') and the Dotted Butterflyfish (''C. semeion''), but these are already so distant that their ancestors must have diverged from those soon after the ''Rabdophorus'' lineage started to diversify. The Spot-tailed Butterflyfish is found at depths between 3 and 15 m in

coral reefs A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

. They occur in coral-rich areas of reef flats,

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'') ...

s and seaward reefs. Juveniles tend to keep inshore. Adults are usually seen in pairs. These fish feed on soft coral polyps (e.g. '' Litophyton viridis'' and species of the genera '' Clavularia'', '' Nephthia'' and '' Sarcophyton'').

References

External links

* Chaetodon Fish described in 1831 Taxa named by Georges Cuvier {{Chaetodontidae-stub