Eptatretus nelsoni (Kuo, Huang & Mok 1994)

Gill apertures usually 5 (4-6). Slime pores: prebranchial 14-20; branchial 0; trunk 35-39; tail 6-10; total 57-67. Gill apertures nonlinear and crowded.

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 (Ref. 51361 ).

A dwarf species; males develop testes at about 20 cm and a 22.4 cm female had elongated eggs; a 26.8 cm specimen had eggs 2.4 cm long; and a 24.4 cm specimen had 11 eggs about 1.5 cm long with polar caps already forming (Ref. 51420).

分布於台灣的西南海域。

目前已知僅捕獲一隻標本，極為罕見。

體延長呈圓柱狀，體後方側扁。眼退化為皮膚所覆蓋。無上下頜。口腔外緣具四對鬚；口腔外側左右各有兩列齒，其內列齒之2-3顆齒之基部愈合，齒列式8+3/2+7，總數為35。鰓孔每側4個，彼此間距小，呈曲線排列，左側最後一個大於其餘鰓孔。體側各有一列黏液孔，可依位置區分為鰓前區、鰓區、鰓肛區及肛後區等四區，本種魚之鰓區不具黏液孔，故黏液孔數分別為19+0+35+8，總數為62。無鱗。肛門位於體後端。無背、臀、胸及腹鰭，僅有尾鰭。體色呈灰褐色，背部中央無白帶。本種為1994年由郭建賢等人發表於台灣的新種/Quadratus nelsoni /及/Paramyxine nelsoni/為其同種異名。

棲息於近海50-200公尺間之泥沙底海域。活動力較弱，主要以死魚或其它無脊椎動物的屍體為食。捕獲時，全身會分泌許多黏液並捲成一團，藉以爭扎以利脫困。