The whale shark is a real marine giant that plows the waves of warm seas and oceans like a living submarine. It grows to one and a half tens of meters in length and reaches an impressive weight of 30 tons. But these creatures do not justify the formidable name “shark” at all, because they feed only on plankton, and by nature are inert and absolutely harmless.
Whale sharks are still a little-studied species, although their distribution range is extremely wide: they live in all moderately warm tropical seas and oceans with the exception of the Mediterranean Sea. A significant part of the information about the lifestyle and even about the sizes of these good-natured giants is based only on stories and conjectures not confirmed by facts.
It is known that, on average, a whale shark reaches 12 meters in length, and that females are larger than males. During the day, they look for food, rising to the surface of the water warmed by the sun, and at night they again descend to a depth of about 700 meters. These sharks swim quite slowly, their speed on average is only 1 km / h. The reason is that they do not use the tail for movement, like most fish, but wave the back of the body from side to side in waves.
If necessary, the whale shark can make a powerful leap and develop a speed of up to 4 km / h. But this happens extremely rarely, since there is no need for a shark to chase prey. The food itself literally swims in her mouth.
Scientists attribute whale sharks to migratory fish, but there is no direct evidence of this fact. Their movement over long distances may simply be associated with the search for a more nutritious environment. As you know, 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 Ningalu Reef.
Whale sharks most often stick together in small flocks of up to ten individuals. Less commonly, single sharks or large concentrations of these fish can be found. Their maximum concentration was observed off the coast of Yucatan in 2009, when observers counted more than four hundred of these giants.
Cetaceans are extremely lethargic and slow compared to other shark representatives. This is often used by scuba divers, swimming close to sharks and even climbing on them while moving.
Appearance
The whale shark has a flattened head with a huge transverse mouth. She has very large gill slits. A characteristic pattern is clearly visible on the back - light spots and stripes staggered against a dark blue or gray background. Her belly is white. Longitudinal protrusions are visible along the body. They probably play a role in coordinating fish movements .
In the mouth of the shark there are a lot of small teeth - up to 15 thousand. But they do not play any role in catering.
Scientists believe that the whale shark lives about 60 years.
Nutrition
The main diet is plankton, nekton, small crustaceans, small schools of flocks, less often squids and tuna. A whale shark searches for the largest accumulation of food through its sense of smell. She has visually impaired eyes, so the nostrils replace her vision.
Whale sharks actively absorb water like a vacuum cleaner, and then pass their gills through the filter. So the food gets into their mouth. Within an hour, the shark “pumps” almost 60 thousand liters of water through itself.
Periodically, the giant shark “coughs”, clearing its gills and freeing them from the adhering remains of plankton.
Shark breeding
Very little is known about this process, although observations have been conducted for more than a hundred years. It is currently known that this fish is ovoviviparous. In egg capsules, embryos develop that hatch even in the mother’s womb. Newborn sharks are very small relative to the body size of an adult - their length is only about 50 cm. At the same time, small sharks have large internal reserves of nutrients, which allows them to do without food for more than two weeks.