Asterorhombus cocosensis (Bleeker, 1855)
Cocos Island flounder
Asterorhombus cocosensis
photo by FAO

Family:  Bothidae (Lefteye flounders)
Max. size:  11.97 cm SL (male/unsexed)
Environment:  demersal; marine; depth range 1 - 30 m
Distribution:  Indo-West Pacific: Mozambique to Fiji; north to Japan, south to Queensland, Australia (not occurring nonmarginally on the Pacific Plate).
Diagnosis:  Dorsal soft rays (total): 79-83; Anal soft rays: 59-64; Vertebrae: 35-36. This species is characterized by the following: body depth 51.5-58.3; sexual dimorphism in interorbital width, in specimens approximately 6.0 cm SL, males 4.1-7.9, females 3.2-5.0; first dorsal-fin ray isometric relative to SL, with distinct membranous structure confined to tip. Pectoral fin count at the ocular side 10-13, blind side 8-11. The membranous structure at the tip of the first dorsal fin resembles a small fish or crustacean (possibly a small hippolytid shrimp), authors called the ray the illicium and the structure at the tip as the esca (Ref. 57759).
Biology:  Found on pale sandy substrates in clearwater coastal bays to outer reef lagoons and sandy gutters on reef flats. Often crawls over low stony reef (Ref. 48637). The membranous structure at the tip of the first dorsal fin resembles a small fish or crustacean (possibly a small hippolytid shrimp), authors called the ray the illicium and the structure at the tip as the esca. The illicium waves the esca back and forth near mouth to attract prey. Shows sexual dimorphism in width of the interorbital origin, wider in males than females. Most frequently collected by divers.
IUCN Red List Status: Least Concern (LC); Date assessed: 03 March 2015 Ref. (130435)
Threat to humans:  harmless


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