The purpose of these aggregations is yet unclear no definite mating behavior has been observed between the sharks. These aggregations consist entirely of large adults, with females outnumbering males by almost three to one. Off southeast Queensland, aggregations of several hundred zebra sharks form every summer in shallow water. Known parasites of the zebra shark include four species of tapeworms in the genus "Pedibothrium".Zebra sharks are usually solitary, though aggregations of 20–50 individuals have been recorded.
This species may be preyed upon by larger fishes and marine mammals. The slender, flexible body of this shark allows it to wriggle into narrow holes and crevices in search of food, while its small mouth and thickly muscled buccal cavity allow it to create a powerful suction force with which to extract prey. The zebra shark feeds primarily on shelled molluscs, though it also takes crustaceans, small bony fishes, and possibly sea snakes. In a steady current, they have been seen hovering in place with sinuous waves of their tails. Zebra sharks are strong and agile swimmers, propelling themselves with pronounced anguilliform undulations of the body and tail. They become more active at night or when food becomes available. Reef channels are favored resting spots, since the tightened space yields faster, more oxygenated water. The shark, a 1.9 m long mature female, was unusual in that albino animals rarely survive long in the wild due to their lack of crypsis.ĭuring 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. In 1964, a partially albino zebra shark completely lacking spots was discovered in the Indian Ocean. There is substantial variation in pattern amongst adults, which can be used to identify particular individuals. As the shark grows to 50–90 cm long, the dark areas begin to break up, changing the general pattern from light-on-dark stripes to dark-on-light spots. The color pattern in young sharks is dark brown above and light yellow below, with vertical yellow stripes and spots. Males and females are not dimorphic in size. The zebra shark attains a length of 2.5 m, with an unsubstantiated record of 3.5 m. The caudal fin is almost as long as the rest of the body, with a barely developed lower lobe and a strong ventral notch near the tip of the upper lobe. The pectoral fins are large and broad the pelvic and anal fins are much smaller but larger than the second dorsal fin. The dorsal midline ridge merges into the first dorsal fin, placed about halfway along the body and twice the size of the second dorsal fin. There are five distinctive ridges running along the body in adults, one along the dorsal midline and two on the sides. There are 28–33 tooth rows in the upper jaw and 22–32 tooth rows in the lower jaw each tooth has a large central cusp flanked by two smaller ones. The mouth is nearly straight, with three lobes on the lower lip and furrows at the corners.
Each nostril has a short barbel and a groove running from it to the mouth. The last 3 of the 5 short gill slits are situated over the pectoral fin bases, and the fourth and fifth slits are much closer together than the others. The eyes are small and placed on the sides of the head the spiracles are located behind them and are as large or larger. The zebra shark has a cylindrical body with a large, slightly flattened head and a short, blunt snout.
0 kommentar(er)
