At the Aquarium
In the water with a leopard shark
Leopard sharks have a reputation for being docile toward people, says Manny Ezcurra, who has handled the Aquarium's leopard sharks since 1996. "But they're not so docile toward invertebrates and small fishes. We have to be careful about who we put in the exhibit with them," he says.
Manny rotates his leopard sharks among several exhibits as the animals grow up. He has to make sure the leopards don't tempt hungry sevengill sharks, larger relatives that are also on display at the Aquarium. So he keeps small leopard sharks in the Slough exhibit. As they grow, they move up to the wave pool of the Aviary exhibit, then into the Kelp Forest. Finally, when they're near full size, they go into the Deep Reef exhibit with the big fish.
When they're first brought in to the Aquarium, wild leopard sharks do require a little care. Often they have parasites called copepods living on their skin—a problem that's common in many sharks. "But leopards are fairly clean compared to other sharks," Manny says. "You can just pluck them right off." After the sharks have been in captivity for a while they get used to food like squid, fish, and prawns, often handed to them by divers. "They'll even swim up to the sevengills and take the food away from them—you'd never see that in the wild," Manny says.
Out in the bays and estuaries, squid and prawns make up only a small part of a leopard shark's diet, but Manny can't provide his charges too many of their staple foods such as shore crabs and fat innkeeper worms. "We buy food according to the Seafood Watch card," Manny says, and there doesn't seem to be too many markets selling fat innkeeper worms.
Natural History
Leopards of the sea
Leopard sharks are one of the most common sharks along the coast of California. They're beautiful, slender fish with silvery-bronze skin, patterned with dark ovals that stretch in a neat row across their backs. (Look closely at the dark spots—the older a leopard shark is, the paler the interior of the spots.) Sturdy, triangular pectoral fins are matched by two dorsal fins, and a long, tapered tail swishes gracefully back and forth.
Leopard sharks live in shallow waters of bays and estuaries and occasionally patrol the kelp forest, usually staying near the bottom. They are rarely found in water more than 65 feet deep, although they have strayed as deep as 300 feet. At the other extreme, they often follow the high tide to feed on shallow mudflats, then move back out again as the water recedes.
Shark pups
Baby sharks are called pups. Unlike most fish, which lay eggs, mother leopard sharks keep their eggs inside their bodies until they hatch. After 10 to 12 months, she gives birth to a couple dozen wriggling shark pups, each about 7 inches long.
Keeping the eggs safe inside her is a good way to make sure they all hatch, though it's also a reason why leopard sharks have so few young—at least compared with the thousands of eggs many other fish lay . Female leopard sharks are usually about 10 years old when they have their first litter, but after that they generally mate every year.
Swim or sink
Leopard sharks are at home on the sea floor, just a foot or so above the sand. This is because they, like all sharks, lack the swim bladders that other fish use to fine-tune their buoyancy. Instead, leopard sharks store oil in their enormous livers. All that oil helps to counterbalance the shark's own weight, but they usually remain slightly less buoyant than the water around them, so they tend to sink whenever they're not swimming.
Bottom feeders
Leopard sharks are made to feed on the bottom—a good thing for a shark that sinks. Their mouths are on the flat underside of their heads, and they open downward. Almost all sharks have sub-terminal mouths except for the whale shark and megamouth sharks. Skimming above the sandy surface, the sharks pluck up crabs, clam siphons, fish eggs, and the burrowing, hot-dog-shaped fat innkeeper worm.
As leopard sharks get older, they start eating more fish and fewer crabs. Leopard sharks have been found with smoothhound sharks, bat rays, and even octopuses in their stomachs.
Shovel for your supper
How do leopard sharks get at buried prey? Divers have seen them swimming stealthily just above the sand, looking for the fleshy siphon of a clam sticking two or three inches above the bottom. If the shark is quick enough, it can grab the siphon in its teeth and yank it out of the sand, occasionally getting the whole clam in the process.
Other times the clam senses the predator and yanks its siphon back to safety. In this case—as well as when the shark goes after innkeeper worms—the shark shovels its nose into the sand. With a mighty twist of its body, the shark unearths a pile of sand and, if it's lucky, gets a clam or worm for its trouble.
Conservation
Leopard sharks live close to shore and have firm, light meat that tastes good, so they're popular with fishermen.