McCosker's hagfish (Eptatretus mccoskeri), first described by McMillan, 1999 is a medium-sized fish in the family Myxinidae (order Myxiniformes). Adults typically reach 32.00 cm in maximum length. It inhabits marine coastal and open-ocean environments. Recorded depth range: 155 to 215 metres. It occurs in Deep-water waters. Diet is predominantly piscivorous, targeting other fish and larger prey. On the IUCN Red List, it is classified as Least Concern.
This species is distinguished from its congeners, except Eptatretus poicilus by the following characters: gill apertures 8 pairs (7 in one specimen), well-spaced and arranged in a near straight line; a 3/3 multicusp pattern of teeth; differs from Eptatretus poicilus by its number of trunk pores 38-43 (vs. 45-50), by the number of total pores 69-75 (vs. 78-86) and by its colour pattern, with body purple to purplish brown (vs. body strongly mottled with pale brown, dark brown and white-beige) . : eel-like; Cross section: oval.
Behavioural data for McCosker's hagfish is currently being reviewed.
Copulatory organ absent. The gonads of hagfishes are situated in the peritoneal cavity. The ovary is found in the anterior portion of the gonad, and the testis is found in the posterior part. The animal becomes female if the cranial part of the gonad develops or male if the caudal part undergoes differentiation. If none develops, then the animal becomes sterile. If both anterior and posterior parts develop, then the animal becomes a functional hermaphrodite. However, hermaphroditism being characterised as functional needs to be validated by more reproduction studies .
Marine; demersal; non-migratory; depth range 155 - 215 m . Deep-water Southeast Pacific: Galapagos Islands.
Occurrence records from the Global Biodiversity Information Facility (GBIF) - 1 records indexed .
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