Whales and sharks are cold jokes.

Many people mistakenly believe that whales are the biggest fish in the world. Although whales are big, they are members of the mammalian family. The record holder of the king of fish is a whale shark. Whale shark is the largest fish in the world. They are not whales, but members of the shark family. When we think of sharks, we can always think of the white death in Jaws, a horror film directed by Spielberg, and images of blood and killing always flash in our minds. If you really have similar thoughts, you have some misunderstandings about whale sharks. They are not fierce sharks. Whale sharks are gentle. They are filter-eaters, constantly shuttling through the plankton-rich ocean, and regularly appear in these seasonal food outbreaks every year to devour plankton. Like most whales, they are only eat small fish shrimp, which is different from many sharks.

Perfect evolution

After hundreds of millions of years of evolution, the shape of whale sharks has undergone tremendous changes. Unlike most sharks in the ocean parade, whale sharks are particularly fat. Unlike other sharks, they have a very heavy flat head and look like an "enlarged version" of catfish.

The whale shark's mouth is 1.8 meters to 2 meters wide, and this huge mouth can even ensure a person to swim comfortably in it. When fully mature, it can reach 12 ~ 20 meters long and weigh about 12 tons. With such a huge body shape, there are three key adaptive characteristics to ensure that they can stay in the water smoothly: one is the obvious ridge protrusion in the back half of their bodies; Second, their tail stems or fleshy handles are the body balancers to prevent them from tumbling when whale sharks cruise; Finally, whale sharks have oversized tails and breasts, and these structures can also help them keep balance.

Long distance migration

Whale sharks eat in exactly the same way as most whales. When they cruise underwater, they usually eat passively with their mouths open. They inhale a lot of water. When the water passes through five large gill flaps, food particles such as eggs or larvae of invertebrates and fish will be screened out by a fine odontoid process and swallowed. Many people mistakenly believe that whale sharks have no teeth. In fact, whale sharks have teeth, but the real teeth are very small and don't work when eating. Few sharks use a similar way of eating. Most sharks will attack their prey directly, then kill it, bite off large pieces of meat with their teeth and swallow it. Among other sharks, only basking sharks and giant basking sharks eat in this way. These are very primitive sharks.

Like whale sharks, these sharks all have one thing in common. They are highly migratory species. Scientists speculate that they need to constantly migrate to find the sea area where plankton gather. After all, their huge size requires a lot of plankton for food. The number of monitor lizards is very small, and we know very little about them. The samples captured by humans are very limited. Scientists have learned about the living habits of basking sharks and whale sharks, and their migration activities can be summarized as endless movement between different food peaks in different seasons. In addition, when they move long distances between different feeding areas, they may not have a chance to eat.

Whale sharks have two active ways of eating, sometimes suspended vertically in water, sucking small fish, tropical krill or jellyfish from surface seawater. Occasionally, several whale sharks cooperate on the surface of the water to drive their prey into a dense encirclement network, but this is rare. Most whale sharks usually act alone and don't like to cooperate with each other most of the time.

Looking for warm ocean currents

The distribution of whale sharks around the world is strongly influenced by the warm current, and these marine behemoths can't stand the low temperature. They can't live in the sea where the water temperature is lower than 20℃, but only in tropical and subtropical waters, and their preferred seawater temperature is between 2 1 ~ 26℃. Whale sharks often appear in lagoons around coral islands and coastal reefs, which indicates that they may stay in the preferred sea areas and can only reach the deep sea during migration, but it also reflects the difficulty of locating whale sharks in the high seas.

Whale shark is one of the most popular marine animals. Because they are gentle, many divers can swim with them. The best places to observe whale sharks include Ningaloo Coral Reef in Western Australia, Seychelles and Maldives in the Indian Ocean, and islands off the coast of Honduras and Belize in the western Caribbean. Most of the time, whale sharks can tolerate divers approaching cruise ships, which makes the fish tourism in the world grow rapidly, earning an estimated 25 million pounds a year.

The mystery of whale shark migration

Scientists first put forward the theory of whale shark's long-distance migration. Some scientists believe that they breed in the Indian Ocean, and then enter the Atlantic Ocean southward with the Mozambique current near South Africa. After reaching the Atlantic Ocean, they reach the Caribbean Sea along the Southern Equatorial Current. Due to the limited knowledge of this animal, this statement has not been confirmed. Although individual whales tracked by satellites do migrate for a long time, for example, a whale shark in the Pacific has migrated for 22,500 kilometers in 40 months, and the migration distance is really amazing, but there is no reliable view to support the migration route of whale sharks speculated by scientists.

But now some scientists believe that whale sharks are more likely to migrate short distances in the ocean than to travel long distances across the ocean. For example, many whale sharks will gather in the south of New Guinea in September, moving southward from 1 1 to 12 to the Great Barrier Reef, and then southward to the east coast of Australia Island (its journey back to New Guinea is still a mystery). Similar regional movements may also occur in the Gulf of Mexico, the Indian Ocean and the Pacific Ocean. The specific migration route of whale sharks has not yet been determined, and marine biologists have different opinions.

The unique white spot on the whale shark's back is innate, and it does not change with age like human fingerprints, which allows researchers to identify individual whale sharks and then describe their moving trajectories. In the past, this analysis was achieved by painstakingly studying the photos of whale sharks taken at sea. Now, the satellite mapping software originally used by the National Aeronautics and Space Administration (NASA) to catalogue galaxies can be used to identify individual sharks. Studies have shown that whale sharks have a very strong impulse to go home-they will firmly remember their main feeding places, almost like being controlled by clocks, and arrive at the same feeding area within a few weeks every year. In the future, with the deepening of research, we may be able to solve the mystery of this deep-sea migration.