Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Acanthuridae (Surgeonfishes, Tangs and Unicornfishes)

Genus/species: Naso unicornis

GENERAL CHARACTERISTICS: Naso unicornis is gray to olive with blue tail spines.  The short forehead horn does not project past mouth. The peduncular plates and spines are blue; dorsal and anal fins yellowish with narrow blue stripes. Adult males tend be larger and have a better developed horn, peduncular spines, and caudal filaments than females.

Length to 70 cm (27.5 in)

DISTRIBUTION/HABITAT: Indo-Pacific. The Bluespine Unicornfish inhabits channels, moats, lagoons and seaward reefs with strong surge. It typically occurs  in small groups at depths of 1–80 m (3-250 ft.).

DIET IN THE WILD: It is diurnal feeding on macro- and micr oalgae, including brown algae like Sargassum.

REPRODUCTION: External fertilization. Pair-spawning has been observed; pelagic larvae.

PREDATORS: An important food fish on most tropical islands. Long-lived, up to 35
years. Preyed upon by other fishes.

CONSERVATION: IUCN; least concern.

REMARKS: Rostral horn responsible for species’ common name. Surgeonfishes have a single scalpel-like peduncular spine which folds into a groove while unicornfishes have 1 or 2 sharp, fixed keel-like peduncular plates. The spines are used offensively and defensively.


California Academy of Sciences Steinhart Aquarium Philippine Coral Reef 2016

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