Have you ever stared at the Caspian Sea and wondered what if it had a shark? Ever really wanted to ask yourself this question? If yes, then let us ease your mind because the Caspian Sea has no sharks at all. So now that this is clear to you, you have to ask the question why no shark swims in the Caspian Sea.
Sharks are cartilaginous marine organisms. Cartilaginous marine life also lives only in salt water, so the water of the Caspian Sea, which is one of the fresh or low-salt waters, is not suitable for shark life. This is the answer to why no shark swims in the Caspian Sea!
Fish that are bony have a sac called the swim bag, which helps the fish stay afloat and balance. Cartilaginous fish, like sharks, do not have these sacs in their body structure. They use their fatty livers to do this. Since the density of salt water is higher than the density of fresh water, fish must work too hard to survive in fresh water. So, they have no choice but to lubricate their livers so that they can stay afloat, which puts a lot of pressure on them, or they have to swim constantly in the water. This also causes them to lose a lot of energy. Interestingly, thousands of species of cartilaginous fish now live in the world, of which 5% are able to survive in freshwater.
Therefore, from all this, it can be concluded that the entry of sharks into the Caspian Sea, whose salinity is very low, is not in the interest of these fish at all. If sharks enter the shallow waters of the Caspian Sea, they not only have to use their kidneys so hard to expel excess water, but they also have to lose a lot of energy due to constant swimming. That is why sharks should not be found in lakes.
Sharks can be divided into different categories according to their degree of temperature tolerance. The three main categories include tropical, polar, and thermal. Hammer sharks and nurse sharks are two well-known species of tropical sharks that live in the ocean. Polar sharks live near polar ice caps. In fact, their body structure is such that they can easily survive in the frozen temperature. Examples of polar sharks include the black dogfish and the sleepy Greenland shark.
Thermal sharks live in waters between these polar and tropical regions. Larger Thermal sharks, such as white sharks, may sometimes travel from the ocean to the tropic regions. But smaller Thermal sharks cannot withstand such changes in water temperature and therefore remain in the same area as they are because it is more comfortable for them.
Different species of sharks may live in different parts of the world. They have lived on this vast land for 420 million years. The shortest shark there is known as the dwarf shark, which is only 17 cm tall, while the tallest species of shark in the world, the Wali shark, is about 12 meters long. Sharks live in all oceans up to 2,000 meters deep. They have very strong and deadly teeth and jaws, yet of all the sharks out there, white sharks, white-tailed sharks and tiger sharks have deadly attacks on humans.
