Zebra shark

Adult zebra sharks are distinctive in appearance, with five longitudinal ridges on a cylindrical body, a low caudal fin comprising nearly half the total length, and usually a pattern of dark spots on a pale background.

Young zebra sharks under 50–90 cm (20–35 in) long have a completely different pattern, consisting of light vertical stripes on a brown background, and lack the ridges.

At night, they actively hunt for molluscs, crustaceans, small bony fishes, and possibly sea snakes inside holes and crevices in the reef.

The zebra shark is oviparous: females produce several dozen large egg capsules, which they anchor to underwater structures via adhesive tendrils.

Innocuous to humans and hardy in captivity, zebra sharks are popular subjects of ecotourism dives and public aquaria.

The World Conservation Union has assessed this species as Endangered worldwide, as it is taken by commercial fisheries across most of its range (except off Australia) for meat, fins, and liver oil.

No type specimen was designated, though Seba included a comprehensive description in Latin and an accurate illustration of a juvenile.

This name was omitted in Compagno's review in 1984, possibly due to confusion over its year of description (in a publication in 1941, Fowler mistakenly listed it as being described in 1795).

[2] Due to their different color patterns and body proportions, both juveniles and subadults have historically been described as separate species (Squalus tigrinus and S. longicaudatus respectively).

As the shark grows to 50–90 cm (20–35 in) long, the dark areas begin to break up, changing the general pattern from light-on-dark stripes to dark-on-light spots.

[10] A rare morph, informally called the sandy zebra shark, is overall sandy–brown in color with inconspicuous dark brown freckles on its upperside, lacking the distinct dark-spotted and banded pattern typical of the species.

The appearance of juveniles of this morph is unknown, but subadults that are transitioning into adult sandy zebra sharks have a brown-netted pattern.

[2] The zebra shark occurs in the tropical waters of the Indo-Pacific region, from South Africa to the Red Sea and the Persian Gulf (including Madagascar and the Maldives), to India and Southeast Asia (including Indonesia, the Philippines, and Palau), northward to Taiwan and Japan, eastward to New Caledonia and Tonga, and southward to northern Australia.

[3][5] Bottom-dwelling in nature, the zebra shark is found from the intertidal zone to a depth of 62 m (200 ft) over the continental and insular shelves.

[11] During the day, zebra sharks are sluggish and usually found resting on the sea bottom, sometimes using their pectoral fins to prop up the front part of their bodies and facing into the current with their mouths open to facilitate respiration.

Zebra sharks are strong and agile swimmers, propelling themselves with pronounced anguilliform (eel-like) undulations of the body and tail.

[12] The zebra shark feeds primarily on shelled molluscs, though it also takes crustaceans, small bony fishes, and possibly sea snakes.

Many zebra sharks at diving sites have become accustomed to the presence of humans, taking food from divers' hands and allowing themselves to be touched.

The small, attractively colored young also find their way into the hands of private hobbyists, though this species grows far too large for the home aquarium.

[20] Zebra sharks are highly susceptible to localized depletion due to their shallow habitat and low levels of dispersal between populations, and market surveys suggest that they are much less common now than in the past.

They are also threatened by the degradation of their coral reef habitat by human development, and by destructive fishing practices such as dynamiting or poisoning.

Female zebra shark at the Children's Aquarium at Fair Park
Early taxonomists thought that juvenile zebra sharks were a different species because of their different appearance from adults.
Close-up of zebra shark
Zebra sharks are often seen resting on sand near coral.
Several egg cases of the zebra shark
A juvenile zebra shark with a color pattern intermediate between that of young and adults