Leopard catshark

The leopard catshark is the smaller and slimmer of the two Poroderma species. The head and snout are short and slightly flattened, with a somewhat pointed snout tip. Each nostril is split into tiny incurrent and excurrent openings by a three-lobed flap of skin in front, of which the central lobe forms a slender barbel that reaches past the mouth. The horizontally oval eyes are equipped with rudimentary nictitating membranes (protective third eyelids) and placed rather high on the head, with a thick ridge running under each. The mouth is wide and arched, with short furrows at the corners extending onto both jaws; the upper teeth are exposed when the mouth is closed. There are 18–30 and 13–26 tooth rows on either side of the upper and lower jaws respectively. The teeth have a narrow central cusp with a pair of small lateral cusplets; those of adult males are slightly more curved than those of females. The body is rather laterally compressed and tapers towards the tail, with two dorsal fins set far back. The first dorsal fin originates over the rear of the pelvic fins and is much larger than the second, which originates over the midpoint of the anal fin base. The bases of the pectoral and pelvic fins are about equal; the pectoral fins are large and broad while the pelvic fins are much lower. Adult males have stubby claspers with the inner margins of the pelvic fins partially fused over them to form an "apron". The caudal fin is short and broad, with an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The very thick skin is covered by well-calcified dermal denticles. Each denticle has an arrowhead-shaped crown with three posterior points, mounted on a short stalk. The background color of the leopard catshark ranges from off-white to glossy jet black above and white to almost black below, sometimes with an abrupt transition between the two. Overlaid is a striking pattern of black markings variously combining small to large spots, blotches, complete to incomplete rosettes, and/or short to long lines, that may extend almost to the midline of the belly. There are four named forms: 'typical', with leopard-like rosettes and broken lines, 'marleyi', with large round spots, 'salt and pepper', with densely packed dots, and 'melanistic', with an almost completely black upper surface and irregular stripes and/or spots; many sharks are intermediate between these forms. Color pattern is affected by development: all hatchling sharks have large black spots, that with age tend to break up into rosettes and smaller spots, that may eventually merge into lines. The 'marleyi' form appears to be a type of paedomorphosis, in which in the hatchling pattern is carried into adulthood. Color pattern is also related to geographic location, with the 'marleyi' and 'salt and pepper' forms apparently restricted to the waters off the Eastern Cape and KwaZulu-Natal. The leopard catshark reaches a maximum known length of 84 cm (33 in) and a maximum known weight of 3.2 kg (7.1 lb); males grow slightly larger than females.