How does the shark sleep? Features of life and development of sharks
At present, about 400 species of sharks are known: from the smallest (15 cm in length) to the giants (18 m in length). They have their own characteristics, but there are common features inherent in almost all types:
- Sharks are intelligent animals, the ratio of their brain to body weight reaches the indices of some mammals.
- The average life expectancy is 30 years.
- Sharks are highly developed sense of smell and hearing, and there is also an unusual sense organ - the Lorenzini electroreceptors.
- They catch electromagnetic waves.
- Skeleton of sharks cartilaginous.
However, there are a number of features that distinguish sharks from other animals and give greater mystery: for example, how the shark sleeps, how it feeds, moves and hunts.
Huge teeth 5 cm long instill horror. On average, the predator has 4-6 rows of teeth, but some individuals can have up to 20. When the front tooth falls out, the tooth from the back row moves to replace it. By the way, losing your teeth for a shark is a common thing. For 10 years, the individual of the tiger shark can change up to 24 thousand teeth. The process of shifting occurs with such frequency because of the peculiarities of the structure of the jaw: the teeth are attached directly to the gum.
Absence of a swim bladder
Unlike other fish, sharks do not havebubble. Therefore, the animal is constantly in motion. If you stop working with your tail, the shark will sink to the bottom. Despite the absence of a bubble in all individuals, there is a predator species that can stay afloat without additional effort. This is a sand shark: it can swallow air and keep it in itself for several hours.
How the Shark sleeps
And how does the sharks sleep in the oceans? Sharks that live in deep waters, almost never sleep, because, having ceased to work with tail and fins, they will sink to a great depth, not intended for them. Simpler to those individuals who live in the depths constantly - they can find time for "sleep." Speaking about whether the sharks are asleep, you can safely give a negative answer.
Hunting for prey
Sharks are very bloodthirsty. Feeling the slightest smell of blood, they immediately go to search for the victim. In hunting they are helped by a developed sense of smell. Only 1 gram of fish blood per 1 million grams of water is enough to feel the victim. However, if you close the nostrils to a predator, then the reaction to the victim will not follow, and the shark will float by.
When the shark has already smelled its prey, it canbegin "hungry rabies." At this moment the predator manifests a special rage, it crushes and swallows everything on the way. In the end, in the stomach, which can expand several times, there may be many unusual things.
As for sharks who prefer plankton and small fish, these species pass through themselves not one hundred liters of water to eat their favorite food. They are not dangerous to man and are peaceful.
Interesting facts about sharks
Sharks are rather unusual creatures, of whichyou can speak endlessly. They exist for millions of years and at the same time they perfectly adapt to any conditions of life. Predators survived the dinosaurs and are clearly not going to die out. Here are some interesting facts about sharks:
- The young sharks have teeth at birth.
- Sharks can distinguish colors.
- The main food Polar sharks are polar bears and deer.
- Some species can jump to a height of 10 m.
- To saturate the body in an animal, 3-14% of the body weight per week is sufficient.
- There are sharks-long-livers whose life expectancy reaches 100 years.
Having learned how sharks sleep, how they feed and exist, you can understand that this is a unique species of fish that has a long history.
