Τρίτη, 23 Μαΐου 2017

Will the real zebra shark please stand up (or swim by)?

The zebra shark (Stegostoma fasciatum) is sometimes called the leopard shark, the common name for Triakis semifasciata. We found that out when we mistakenly showed images of Stegostoma fasciatum in a story about a mortality event involving Triakis semifasciata in San Francisco Bay.

So we wanted to set the record straight, and present some fun facts about zebra sharks.

1) Zebra sharks are born dark brown with yellowish stripes. As they reach adulthood, zebra sharks’ stripes are replaced by small black dots against a tan body. (To make it even more confusing, sometimes zebra shark is used as the common name for the tiger shark, Galeocerdo cuvier.)

2) Zebra sharks are nocturnal. At night, they actively hunt for molluscs, crustaceans and small bony fishes inside holes and crevices in the reef. During the day, they are as sluggish as teenagers getting ready for school and are often found resting on the sea bottom.

3) Barbels — slender sensory organs that look a little like a cat’s whiskers located at the front of their snouts — help them seek out prey. They use their flexible bodies to wriggle into tight crevasses where their favorite prey is often hiding.

zebra shark

Adult zebra sharks have five distinctive longitudinal ridges running along the body, a spotted pattern, and small eyes.

iStock

4) Love hurts: The courtship behavior of the zebra shark involves the male biting vigorously on the female's pectoral fins and tail. (He's not always successful.)

5) The zebra shark is oviparous. Females can several eggs at a time, which they anchor to underwater structures or the seafloor bottom via adhesive fibers. Pups usually measure about 12 inches long at birth; adults can grow to 12 feet.

6) Adult zebra sharks are non-aggressive toward humans, and have few predators other than larger shark species (and humans).

7) Hunted for its meat, fins and liver oil (used in making vitamins), zebra sharks are considered Endangered worldwide by IUCN. The exception, however, is in Australia, where the species is considered of Least Concern because it has a wide distribution and is not heavily fished. In shallow waters off southeast Queensland, aggregations of zebra sharks that number in the hundreds form every summer