The leopard shark is an immediately recognizable, stunningly attractive species, which derives its common name from its distinctive markings of dark brown leopard-like spots set against a yellow-brown skin tone. Juveniles, which are less than 70cm in length, can be distinguished from adults by their markedly different coloration. This consists of narrow white stripes and blotches contrasted against a dark brown base colour, from which its alternative common name of ‘zebra shark' arises. Adults also have prominent longitudinal skin ridges that are lacking in young. This shark has a cylindrical body with large pectoral fins, two close-set spineless dorsal fins and a very long caudal fin, almost as long as the rest of the body. There are five gill slits on the sides of its broad head. Harmless to man, this beautiful shark is approachable, especially during the day as it rests on the seabed.
Range
The leopard shark is found over continental and insular shelves in warm temperate to tropical areas of the Indian Ocean and west Pacific Ocean, and is exceptionally abundant in Australian waters.
Habitat
Leopard sharks inhabit shallow inshore and offshore waters near the bottom, at depths down to around 62m, often found close to coral reefs. Recorded to have entered freshwater in the Philippines but this needs to be confirmed.
Biology
These sharks are mostly solitary but can occasionally be found in aggregations of 20 - 50 individuals. Believed to be a nocturnal hunter, they spend most of the day lazily swimming and resting on the bottom, becoming active at night when they hunt for sleeping fish, molluscs and crustaceans. A slow but powerful swimmer, leopard sharks have unusually flexible bodies that are used to squirm into tiny crevices in search of food. As they do not usually swim in open water their territories are limited to their natal reef or those closely connected.
Female leopard sharks lay large, purplish-black eggs, which they anchor to the floor with many long hair-like fibres. It is likely that more than one egg is laid at a time. Once hatched, the young are independent of their mother. Males reach sexual maturity between 1.5 - 1.8 m and females at around 1.7 m. The longest known lifespan in the wild is 33 years, although leopard sharks usually live an average of 25 years.
Threats
There is no direct evidence of a decline in leopard shark numbers but Indo-West Pacific surveys of local fish markets suggest it is much less common than it used to be. Incidental and deliberate capture by fishing companies is the principal threat to the leopard shark across its range outside Australia; it can be found in fish markets all around Indonesia, Thailand, Malaysia, the Philippines, Pakistan, Taiwan and India. The liver is used to make vitamins and its fins are dried for the Oriental shark-fin trade to be used in soups. Threats in Australia are minimal. Evidence from the Gulf of Thailand show it was historically more abundant and may have been affected by the use of explosives and poisons on reefs.