| Main Ref. | Márquez, M.R., 1990 |
| Appearance refers to |
| specialized organs | |
| different appearance | |
| different colors | |
| remarks |
| Striking features | |
| Body shape lateral | |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Diagnosis | Body mass lower than 50,000 g. Carapace of adults are nearly round. Head: moderate-sized; subtriangular. Hatchlings: longer carapace and larger head. As it grows, carapace changes its shape and becomes a little wider. Head with 2 pairs of prefrontal scales. Carapace: with 5 central, 5 pairs of lateral and 12 pairs of marginal scutes; bridge areas have 4 scutes. Each with a pore which is the opening of the Rathke’s gland. This gland plays a pheromonal role in maintaining the integrity of the massed nesting assemblage of females just off the beaches in which it releases an odoriferous substance before and during their arrival. One visible claw on fore flippers; hatchlings show two, in rear flippers 1 or 2 claws. Color: in adults, plain olive-grey dorsally, white or yellowish underneath; in hatchlings, jet black when wet; changes significantly with age; after 10 months, plastron is nearly white. |
| Ease of Identification | likely to be confused with closely related species. |
| 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 | |
| Fins number | |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | |
| Soft-rays total | |
| Adipose fin |
| Attributes |
| Fins number | |
| Spines total | |
| Soft-rays total |
| Pectoral | Attributes |
| spines | |
| soft-rays | |
| Pelvics | Attributes |
| Position | |
| spines | |
| soft-rays |