Sea giant: whale shark

A whale shark is a real sea giant that waves through waves of warm seas and oceans like a living submarine. It grows to fifteen meters in length and reaches an impressive weight of 30 tons. But these creatures do not justify the terrible name "shark", they feed on only plankton, but are inert and absolutely harmless in nature.

Whale sharks still remain a little explored species, although their distribution range is extremely wide: they live in all temperate warm tropical seas and oceans except for the Mediterranean Sea. Much of the information on the way of life and even about the size of these good-natured giants is based only on stories and speculations, not confirmed by facts.

It is known that on average the whale shark reaches 12 meters in length, and that females are larger than males. In the afternoon they look for food, rising to the sun-heated surface of the water, and at night again descend to a depth of about 700 meters. These sharks are slow enough to swim, their average speed is only 1 km / h. The reason is that, for movement, they do not use the tail, like most fish, but waved the back of the trunk from side to side.

If necessary, a whale shark can make a powerful jerk and develop a speed of up to 4 km / h. But this happens extremely rarely, because there is no need for the shark to pursue prey. Food itself literally floats in her mouth.

Scientists attribute whale sharks to migratory fish, but there is no direct evidence for such a fact. Their movement to distant distances can be linked simply with the search for a more nutritious environment. As is known, in March and April of each year sharks gather in the continental shelf off the western and central coasts of Australia. Most of them are observed near the Ningaloo Reef.

Whale sharks often stay together in small flocks of up to ten individuals. Less commonly, you can find single sharks or large concentrations of these fish. Their maximum concentration was observed near the coast of Yucatan in 2009, when observers counted more than four hundred of these giants.

Whales are extremely apathetic and sluggish compared to other shark representatives. This is often used by scuba divers, coming swiftly to the sharks and even climbing them while driving.

Appearance

The whale shark has a flattened head with a huge transverse mouth. She has very large gill slits. On the back, a characteristic pattern is clearly visible-light spots and streaks, staggered on a dark blue or gray background. Her belly is white. Longitudinal protrusions are visible along the trunk. Probably, they play a certain role in the coordination of fish movements .

In the mouth of a shark there are a lot of small teeth - up to 15 thousand. But in the organization of food they do not play any role.

Scientists believe that the whale shark lives about 60 years.

Food

The main diet - plankton, nekton, small crustaceans, small schooling fish, at least - squid and tuna. The whale shark searches for the greatest accumulation of food with the help of the sense of smell. She has visually impaired eyes, so her nostrils replace her vision.

Whale sharks actively suck water like a vacuum cleaner, and then pass through the filter - their gills. So the food gets to them in the mouth. Within an hour the shark "pumps" through itself almost 60 thousand liters of water.

Periodically the giant shark "coughs", clearing its gills and releasing them from the sticky remnants of plankton.

Reproduction of sharks

Little is known about this process, although observations have been conducted for more than a hundred years. Now it is known that this fish is ovivorous. In the capsules-eggs develop embryos, which hatch in the mother's womb. Newborn sharks are very small relative to the size of the adult body - their length is only about 50 cm. At the same time, small sharks have large internal reserves of nutrients, which allows them to dispense with food for more than two weeks.