| Main Ref. | Compagno, L.J.V. and V.H. Niem, 1998 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks |
| Striking features | |
| Body shape lateral (shape guide) | elongated |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Type of scales | placoid scales |
| Diagnosis |
The smalleye pygmy shark, Squaliolus aliae, is a very small dogfish (about 22cm) characterized by its small eye, with diameter about 46-70% of interorbital width, and with upper margin angular and chevron-shaped; upper lip with a pair of prominent lateral papillae (rarely indistinct) (Ref. 31367, 6871).Colour: dark brown to black, fin margins pale (Ref. 6871). Squaliolus are the only sharks with a fin spine on its first dorsal fin (spine sometimes concealed by skin) but not on its second dorsal fin; second dorsal fin long-based and low, about twice the length of the first dorsal fin base; first dorsal-fin base closer to pectoral fins than to pelvic fins; and caudal fin nearly symmetrical, with subterminal notch present (Ref. 247, 6871). |
| Ease of Identification | easy to distinguish from other 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 | 2 |
| Finlets No. | Dorsal 0 - 0 |
| Ventral 0 - 0 | |
| Spines total | 1 - 1 |
| Soft-rays total | 0 - 0 |
| Adipose fin | absent |
| Attributes | other (see remark); asymmetric |
| Fins number | |
| Spines total | 0 - 0 |
| Soft-rays total | 0 - 0 |
| Pectoral | Attributes more or less normal |
| Spines 0 | |
| Soft-rays 0 - 0 | |
| Pelvics | Attributes more or less normal |
| Position abdominal behind origin of D1 | |
| Spines 0 | |
| Soft-rays 0 - 0 |