Author: Gill, 1862
Diagnostic Features:
Trunk fusiform and moderately stout. Head moderately long but much shorter than trunk; snout moderately long, pointed and conical, not depressed, flattened and bladelike; eyes small; mouth large and arcuate, ventral on head, gill openings extremely large, extending onto dorsal and ventral surfaces of head, all anterior to pectoral fin bases; gillrakers present on internal gill slits, in the form of hairlike modified dermal denticles with extremely elongated crowns; teeth very small, hooklike, not blade-shaped, and in over 200 rows in either jaws; several rows of small anterior teeth in upper jaw, separated from the laterals by a broad gap. First dorsal fin large, high, erect and angular; second dorsal and anal fins moderately large but less than half size of first dorsal, with broad, non-pivotable bases; pectoral fins long and moderately broad, much shorter than head in adults; pelvic fins smaller than first dorsal fin but larger than second; caudal fin lunate, upper lobe moderately long but less than one-third length of rest of shark, lower lobe nearly as long as upper lobe. Precaudal pits present, caudal peduncle depressed and with strong lateral keels.
Remarks:
This family has often been placed in synonymy of the family Lamnidae but, as noted by Springer and Gilbert (1976), is very distinct. Its relationship to the Lamnidae remains unclear.
Priede (1984) details a successful short-term satellite tracking effort on a radiotagged basking shark, Cetorhinus maximum. This space-age methodology promises to reveal some of the secrets of the basking shark's seasonal migrations and movements.