| Main Ref. | Daget, J., 2003 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks |
| Striking features | |
| Body shape lateral (shape guide) | eel-like |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Type of scales | |
| Diagnosis |
Diagnosis: body naked, elongated, cylindrical in front and strongly compressed back; caudal part of body making less than one third of the total length and ending in a blunt point; no paired fins; dorsal and anal fins reduced to a skin fold, rayless, meeting the caudal fin; eyes small, overlaid with skin, situated at the head forward; mouth large with well developed lips; conical teeth to the jaws and the palate; gill opening reduced to a medio-ventral transversal slit; branchiostegal membrane free from isthmus; 4 branchial arches with well developed branchiae; lateral line present; vertebral count: 80 abdominal and 50 caudal (Ref. 57291). Colouration: adults are dark-coloured, nearly black, juveniles are clearer (Ref. 57291). |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | |
| Pored lateral line scales | |
| Scales in lateral series | |
| Scale rows above lateral line | |
| Scale rows below lateral line | |
| Scales around caudal peduncle | |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | |
| on upper limb | |
| total | |
| Vertebrae | |
| preanal | |
| total |
| Attributes | greatly reduced or absent |
| Fins number | 1 |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | 0 - 0 |
| Soft-rays total | 0 - 0 |
| Adipose fin | absent |
| Attributes | pointed; confluent |
| Fins number | 1 |
| Spines total | 0 - 0 |
| Soft-rays total | 0 - 0 |
| Pectoral | Attributes absent |
| Spines | |
| Soft-rays | |
| Pelvics | Attributes suppressed/absent |
| Position | |
| Spines | |
| Soft-rays |