瓜氏虎鯊

fieldmarks: Dorsal fins with spines, anal fin present, first dorsal-fin origin over pectoral-fin inner margins, colour pattern of large dark spots. Supraorbital ridges low, gradually ending posteriorly; interorbital space very shallowly concave, depth between ridges less than one-fourth eye length. Anterior holding teeth with a cusp and a pair of cusplets in adults, posterior molariform teeth strongly carinate and not greatly expanded and rounded. Pre-first dorsal-fin length 32 to 36% and anal-caudal space 4 to 7% of total length. Lateral trunk denticles fairly large and rough. Propterygium separate, not fused to mesopterygium. First dorsal-fin spine directed obliquely posterodorsally in hatchlings to adults; first dorsal-fin origin behind pectoral-fin insertions, over pectoral-fin inner margins and far behind gill openings; first dorsal-fin insertion about opposite pelvic-fin origins and far behind pectoral-fin insertions; first dorsal-fin free rear tip over or behind midbases of pelvic fins and sometimes about opposite pelvic-fin insertions; first dorsal fin rounded and brush-shaped in young and low and rounded-subangular in adults, height 8 to 9% of total length, first dorsal fin subequal to pelvic fins; second dorsal-fin origin slightly to well behind pelvic-fin free rear tips, second dorsal fin rounded-angular and nearly as large as first dorsal fin. Anal fin rounded-angular, apex well anterior or reaching lower caudal-fin origin when laid back; anal-caudal space less than twice anal-fin base. Total vertebral count 103 to 109, precaudal count 67 to 72, monospondylous precaudal count 24 to 36, diplospondylous precaudal count 33 to 41, pre-first dorsal-fin spine count 19 to 20, and count from diplospondylous transition to second dorsal-fin spine 11 to 19. Identification of egg cases uncertain, but possibly like those of H. francisci, with flat thin spiral flanges diagonal to case axis, without tendrils on case apices, and flanges with five turns. A small species, mature between 48 and 61 cm. Background colour of dorsal surface light grey or brown with large black spots greater than half eye diameter, no dark harness pattern; head without a light-coloured bar on interorbital surface and with mottled dark spots or blotches under eye; fins without abrupt dark tips and white dorsal-fin apices; hatchlings without whorls on fins and body and similar in coloration to adults.

Eastern Pacific from the coasts and offshore islands of Peru and the Galapagos Islands.

Maximum total length 61 cm; an egg case possibly from this species was about 11 cm long; an apparently newly hatched male was 17 cm and an adult male was 48 cm long.

A little-known but apparently common tropical and warm-temperate bullhead shark of inshore continental and insular waters, at moderate depths on the bottom. Lives on rocky and coral reefs.Often seen resting on ledges of vertical rock surfaces at 16 to 30 m depth. A poorly known, primarily nocturnal shark. Oviparous. Feeds on crabs; sometimes with marine algae in its stomach.One taken from the stomach of a tiger shark.

Not a commercial species (N. Chirichigno, pers. comm.), though presumably caught as discarded bycatch. Commonly seen by divers off the Galapagos Islands.