Sharks are ferocious, so why aren t there any freshwater sharks?

Sharks are ferocious, so why aren't there any freshwater sharks? If you want to ask what is the most powerful animal in the ocean? You can start by thinking of sharks.

Since childhood, we have the impression that sharks are the overlords of the turbulent sea, they all have to eat people, don't go to the place where the sharks are, and see that they can run fast, but in fact, we have some misunderstandings about them. How much do you know about sharks? Quick facts about sharksMost sharks are actually quite small.

Sharks are ocean-dependent animals that mostly live in the ocean and rarely swim to freshwater areas. People put all sorts of labels, but are actually very fast medium and large fish that swim in the sea. They have no real bone tissue throughout their bodies, and their exoskeletons are underdeveloped and slowly degenerate.

Don't think they're all big fish. In fact, most of them are not 1 m 6 in length, but there are also large species. For example, whale sharks are 20 meters long.

What a "giant" in the shark world. The ferocious "cannibalism" is an example of this. There are only more than 20 species of shark families that eat people, and most of them do not eat people.

According to recent data, there have been only 28 injuries in recent years, and the death rate is declining. This is probably less than the number of incidents of dogs hurting people every year. Biologists are mostly small fish that are generally considered harmless to humans.

Because you are too hungry to eat, you will actively hurt people. Or you run to that area and disturb that life, it might attack you.

In general, their eyesight is really bad. You're wearing a black wetsuit all over, and it can see you as a swimming sea lion, which may be myopic and take off your glasses, without distinguishing between people and livestock. This happened.

A large shark with a sharp attack attacks a human, biting the person in half, only to spit it out again. The reason is, you may not like human flesh. And carnivores like them must have their own fixed predator menus.

Humans are very alien to them and have no taste.

It is known which earthworm's mother was pregnant with which earthworm and was pregnant for three years. But do you know how long it takes for a shark mother to get pregnant to give birth? The answer is four years!

The shark's ability to be a sea bully begins to grow in the mother's belly. They fight for survival in the belly of their "mother", and only those who survive are born. So they grow up slowly, and it takes time to save their hands and feet, so it takes 4 years to be born, and birth is the strongest.

Do you know more about the sharks here?

Because there are very few freshwater resources on the earth, sharks cannot survive in freshwater, and sharks eat a particularly large amount, so there is no distribution of freshwater sharks.

Because sharks are only suitable for living in seawater, they simply have no way to survive in fresh water, which is not their living environment at all.

Because sharks can't survive in freshwater, not only sharks can't survive in freshwater, but even other fish have a hard time adapting.

There are four common types.

1. Silver shark. <>

Silver shark is a small and cute small fish, but also the earliest ornamental shark raised by fish farming, it is native to Thailand and other places, because of the size of the shark so named, but silver shark is a kind of tropical fish with a very docile personality.

2. Red-tailed shark.

The origin of the red-tailed shark is also in Thailand, it is the smallest of all the ornamental sharks and the most colorful body color, their largest body is only 15 cm, don't look at their small size, the temper is not small, the sense of territory is particularly strong, the fight between the same kind is obvious, but with other species of ornamental fish can still live in peace.

3. Blue shark. <>

Blue sharks are larger than the first two, some can grow to more than 50 centimeters or even larger, and can be classified as large fish. Adult blue sharks have the domineering spirit of sharks and will devour small fish, and many people often think that they are sharks in the water.

4. Steller's shark.

Steller shark is native to Thailand, Malaysia and other countries, with fast growth, large size, miscellaneous diet, and low oxygen tolerance. Steller's sharks generally grow to about 30-40 centimeters. However, it depends on how big the fish tank is, and the bigger the fish tank, the faster it will grow.

1. Some are huge, greedy and streamlined, with torpedo-like bodies, with five to seven gill holes on the sides of the head, with a large mouth of blood, which makes the soul fly away at a glance, the shark's body is hard, muscular, and spindle-shaped to varying degrees, and the mouth and nose parts vary from species to species, with pointed, such as the gray mackerel early shark slag sedan chair and the big white shark also have large and round, longer than the shark's shape, wide in front and narrow in the back, streamlined, with dorsal fins, and the tail erected up and down, like a sharp knife, it swims very fast in the water, Like a stroke of lightning and those beautiful and leisurely angelfish.

2. A manta ray with a slender tail and huge wings flying up and down.

3. The most acute organ of sharks is the sense of smell, and they can smell blood sharks from miles away.

4. Can swallow dozens of small fish at once, eat small fish, like a wind and clouds, Sharks are particularly sensitive to smells in seawater, which makes people look intimidating, and describe the shark's sentence: The shark quickly approached the stern.

In the ocean, the shark can be said to be a very ferocious animal, it swims very fast in the land, and can catch up with most fish. The shark has evolved more comprehensively, and its whole body has a variety of sensory organs, among which the most acute sensory organ is its nose, which can smell extremely fine substances such as blood from several kilometers away, and quickly track out the ** of this substance.

At the top of the shark's head is a sensory organ called an electroreceptor, which detects bioelectric currents that the shark uses to hunt prey and swim freely in the water.

Sharks have razor-sharp teeth that cut, tear, and crush prey. Sharks are also said to be able to easily bite through finger-thick submarine cables. Biologists have speculated that the bite force of the megalodon can reach up to tons based on the bite force data of the great white shark.

Sharks are also particularly fond of attacking humans, and sharks attack humans every year around the world. In the face of the shark's bloody mouth, the slightly fragile human has no defense.

There are three species of freshwater sharks: freshwater black shark, freshwater white shark, and river gray beam cover shark.

1. Freshwater black shark: The body of the black shark is elongated and flattened. The abdomen is flattened.

Anterior mouth position, snout with short whiskers. The dorsal fin is tall and triangular in shape, located behind the middle of the fish's body, and resembles the size of a shark overall. The body color is uniformly black, and the males have a darker body color.

The fins are dark black, except for the caudal fin, which is bright orange-red, and the pectoral fin is pale or slightly orange-yellow. The maximum body length can be 12 cm. The body height is fusiformal, 5 to 6 cm long.

2. Freshwater white shark: long and flattened body, obvious bulge on the back, round abdomen, no ventral ridge. The head is flattened and conical, the snout is short, and the gill membrane is not connected to the cheeks.

The upper and lower jaws have small, curved teeth that are closely curved and plate-like. The dorsal fin is located at the highest point of the back and has a stout hard spines. dorsal fin with a fat fin posteriorly above the base of the caudal; There is a well-developed hard spine on the outer edge of the pectoral fin, the pelvic fin is small, the anal fin is long, the caudal fin is forked, and the body surface is smooth and scaleless.

The dorsal body is grayish-black, the sides of the body are blue-gray, and the abdomen is silvery-white.

3. River gray shark: subcylindrical, generally about 1 meter long, flat head, medium length; The tail is slender, the caudal vertebral axis is upturned, the eyes are oval, the snout is pointed and long, the mouth is small, triangular, the upper lip fold is slender and thick, the lower lip fold is slender, the teeth are small and numerous, and the paving is arranged in a stone-like arrangement. dorsal surface greyish-brown, without white spots, ventral surface white, 2 dorsal fins, detached, without hard spines, 1st dorsal fin larger, posterior, beginning opposite or later than the inner angle of pectoral fin.

Rent slag imitation.

Freshwater sharks live benthically and are omnivorous fish, with juveniles feeding on phytoplankton and artificial feed, and adults feeding on aquatic plants and artificial feed. The fish is very greedy, so the growth rate is fast, the individual is large, the adaptability to the environment is strong, rivers, ponds can be cultivated, and the weight can be increased by 1 kg in 8 months. The fish is timid, swims quickly, and is disturbed by the fact that it jumps constantly in the water.

The fish has poor resistance to low temperature, the appropriate temperature is 20 30, the optimal growth temperature is 24 28, when the water temperature drops to 18, the food intake and activity are significantly reduced, and the water temperature is continuously lower than 12 and begins to die. The pH of the growing water is 6. Adaptability and diet. Freshwater sharks have strong resistance to hypoxia and wide adaptability, but their resistance to low temperature is weak.

The suitable temperature is 20 34, the optimal growth water temperature is 26 32, and the activity is slow and the response is slow when the water temperature is lower than 18. Death begins when the water temperature drops below 12. The fish has a mixed diet, the juveniles are fed on zooplankton, and the adults feed on aquatic plants and artificial compound feed, and the feed protein requirement is 28% 32%.

Freshwater sharks have a variety of food habits, large appetite, fast growth rate, fry (3 4 cm) for 4 months, weight can reach more than kilograms. The fish matures late, is reared for 3 to 4 years, and can reproduce when it weighs more than 3 kg. The breeding season is from April to September, and it is a one-time spawning fish of the year.

The fish is long, flattened laterally, with a raised back, a flattened and conical head, a short snout, a sub-inferior mouth, and a gill membrane that is not connected to the cheeks. It is large and has the function of breathing air, so it is not easy to lack oxygen. The cartilage tissue of the fish contains chondroitin sulfate, so in addition to being used for food and ornamental, it also has medicinal value.

The only shark that lives in freshwater, second only to the great white shark in terms of danger, can be called the "wolf of the sea".