Leopard Shark

The leopard shark has a moderately stout body, with a short, rounded snout. There are well-developed, triangular flaps of skin in front of the nares. The eyes are large and oval, with a nictitating membrane (a protective third eyelid). The line of the mouth is strongly curved. There are furrows at the corners of the mouth extending onto both jaws, with those on the lower jaw almost long enough to meet at the midline. The tooth rows number 41–55 in the upper jaw and 34–45 in the lower jaw; each tooth has a slightly oblique, smooth-edged cusp in the center and 1–2 small cusplets on either side. These teeth are arranged into a flat, "pavement"-like surface with overlapping ridges.

The leopard shark occurs in the Northeastern Pacific Ocean, from the temperate continental waters of Coos Bay, Oregon to the tropical waters of Mazatlán, Mexico, including the Gulf of California. It favors muddy or sandy flats within enclosed bays and estuaries, and may also be encountered near kelp beds and rocky reefs, or along the open coast. Numbers have been known to gather near discharges of warm effluent from power plants. Leopard sharks generally swim close to the bottom and are most abundant from the intertidal zone to a depth of 4 m (13 ft), though they may be found as deep as 91 m (299 ft). Many leopard sharks, particularly in the north, leave their coastal habitats in winter and return in early spring.

The diet of the leopard shark consists of small benthic and littoral animals, most significantly crabs (Cancridae, Grapsidae, and Hippoidea), shrimp, bony fish (including anchovies, herring, topsmelt, croakers, surfperch, gobies, rockfish, sculpins, flatfish, and midshipmen), fish eggs, clams, and the echiurid fat innkeeper worm (Urechis caupo). This opportunistic hunter has also been known to eat ghost shrimp, polychaete worms, and the young of smoothhounds, shovelnose guitarfish (Rhinobatos productus), and bat rays (Myliobatis californicus). Eelgrass (Zostera) and algae may be swallowed incidentally.

An active species that swims with a strong undulating motion, the leopard shark is commonly spotted cruising in or just beyond the surf zone. It is more active at night than during the day, and sometimes lies still on the bottom. In Tomales Bay (among other similar regions), the leopard shark follows the tide onto mudflats to forage for food, retreating just fast enough to prevent being stranded or trapped as the water recedes. At Santa Catalina Island, resident sharks spend the day together in the shallows and at night, they disperse into deeper water, up to 10 km (6.2 mi) away.

Wary and quick to flee, leopard sharks pose almost no danger to humans. There was only one recorded incident which was in 1955 of a leopard shark harassing a skin diver with a nosebleed, though no injuries resulted. This species is caught by commercial fisheries using gillnets and longlines, and by recreational anglers and spearfishers; it is also caught as bycatch in bottom trawls. The meat is considered excellent eating and is sold fresh or frozen. However, leopard sharks living alongside human development may accumulate pollutants such as mercury, pesticides, and polychlorinated biphenyls (PCBs) within their bodies, and the California Department of Fish and Wildlife warns against eating them regularly.