Roa butterfly fish

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Roa butterfly fish
Drawing by Roa excelsa

Drawing by Roa excelsa

Systematics
Acanthomorphata
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Surgeonfish (Acanthuriformes)
Family : Butterflyfish (Chaetodon)
Genre : Roa butterfly fish
Scientific name
Roa
Jordan , 1923

Roa is a genus of the butterfly fish family(Chaetodon). The five species belonging to the genus have separate distribution areas and occur in the Red and Arabian Seas to the coast of India , the Philippines , Japan , northern Australia and Hawaii .

features

All four types are very similar to each other. They are 12 to 17 centimeters long, have a laterally flattened, high-backed body and are of a white basic color with three brown, dark-edged horizontal stripes. The first runs from the forehead over the eyes to the lower end of the gill cover, the second extends from the front, hard-edged part of the dorsal fin to the pelvic fins, whose spines are white and the soft rays are brown. The third extends from the soft part of the dorsal fin to the soft part of the anal fin. Young fish have a dark, light-rimmed eye spot in the rear, soft-rayed part of the dorsal fin .

Fin formula : Dorsal XI / 19–24, Anale III / 17–19.

Way of life

For butterfly fish, they live in very deep water, between 100 and 290 meters. Since the fish live in depths that are inaccessible to free-swimming divers and there are no aquarium observations, their way of life is still largely unknown.

History of discovery and systematics

The type specimen was a fish that was killed during an eruption of Mauna Kea in 1919 and found floating on the surface of the sea. It was described as Loa excelsa by David Starr Jordan in 1921 . Since the generic name was already given for the eye worm ( Loa loa ), Roa was chosen as the new scientific name . Roa was later placed as a subgenus of Chaetodon . However, since it lacks a connection between the swim bladder and the lateral line on the supracleithrum (a bone of the shoulder girdle) , in contrast to all other Chaetodon sub-genera, it was raised to the rank of genus again.

species

Another butterflyfish that was photographed by Hans Fricke while searching for the Comoros coelacanth from the German research submersible Jago at a depth of around 200 meters near the Comoros could be a seventh, previously undescribed Roa species.

literature

Web links