The largest animal, the blue whale, can swallow dozens of tons of krill in one gulp, but it cannot swallow a person.

The largest animal that has ever appeared in the history of the Earth did not appear in the distant ancient times, but lived in the same era as us. It is the blue whale.

The body length of a blue whale is usually around 30 meters, and its weight can reach an astonishing 150 tons. There are even records showing that the largest blue whale ever discovered weighed more than 200 tons, which is much heavier than dinosaurs. It is currently believed that the largest dinosaur that has ever appeared in history is the Diplodocus, which can also reach more than 30 meters in length, but its weight is much inferior, and the weight of the Seismosaurus usually does not exceed 40 tons.

So why do blue whales grow so big? In fact, blue whales were not so big from the beginning. There is a process for blue whales to grow from small to large. A long time ago, the ancestors of blue whales did not even live in the ocean. About 50 million years ago, they returned to the ocean from land. At that time, their size was not as big as a leopard.

The first problem faced by whale ancestors returning to the ocean was growing up.

Because water conducts heat 25 times faster than air, whales, as mammals, will lose body heat quickly, so they must grow larger to keep warm. As the body grows, the ratio of surface area to volume gradually increases, so the ratio of heat dissipation relative to the entire body decreases, and the insulation efficiency increases.

In order to grow up quickly, they must eat, and the ancestors of whales seemed to have a disagreement about eating. Compared with land, the food in the ocean is too abundant, so what to eat is indeed a very tangled matter. Some whales decided to feed on large fish, so they retained their teeth. These whales eventually evolved into toothed whales, among which the representatives are sperm whales and baiji. Other whales decided to feed on small shrimps in the ocean, so they abandoned their teeth and evolved a new way of eating. These whales are what we now call baleen whales, and the blue whale is one of them.

Obviously, the feeding strategy of baleen whales, represented by the blue whale, is more intelligent.

Because the number of shrimps is much larger than that of big fish, especially after the evolution of baleen, the feeding efficiency is very high. In the food chain, the energy transfer is decreasing, and the energy transfer efficiency of each level is usually only about 20%, so the blue whale directly locates the food source on the bottom consumers, which can obtain nutrition most efficiently.

Obviously, this feeding strategy is effective. The size of baleen whales, represented by blue whales, is generally larger than that of toothed whales. In this competition of growing bigger and fatter, baleen whales have won a comprehensive victory. For a creature of such a large body, the efficiency of feeding is very important, so they have evolved baleen. When feeding, blue whales will swallow a large amount of seawater and krill into their mouths in one breath, and then squeeze the seawater out of their mouths. The krill are intercepted by the baleen, and the whole feeding speed is very fast.

How much krill can a blue whale swallow in one breath?

A blue whale needs to eat about 4 tons of krill a day. According to the amount of seawater a blue whale can swallow in one breath, if the density of krill is saturated, then this one bite can swallow more than 80 tons of krill. Therefore, a blue whale may only need one bite to eat. This efficiency is really unbeatable.

However, although the blue whale can swallow dozens of tons of krill in one breath, it cannot swallow a human being. In some fantasy novels, we sometimes see people being swallowed by blue whales, or even living in the stomach of a blue whale for a long time. These are impossible in reality because blue whales cannot swallow people at all. Although the blue whale's mouth is large, its throat is very small. The size of the blue whale's throat is about the same as a football. A person cannot pass through such a small hole. The blue whale has such a large appetite. Is there enough krill in the ocean for it to eat? There is no need to worry about this, because blue whales and krill form an independent ecological cycle system.

Krill is a marine organism with a strong reproductive capacity. One krill can produce more than 6,000 offspring in one spawning.

However, the reproduction rate of krill is closely related to the sufficiency of food, and the food of krill is phytoplankton in the ocean, and the amount of phytoplankton is closely related to the abundance of nutrients in the ocean. The feces of blue whales contain a lot of nitrogen, phosphorus and iron, which are indispensable nutrients for the growth of phytoplankton. The feces of blue whales can float on the water surface and are natural nutrients for phytoplankton.

In this way, blue whales, krill and phytoplankton formed a perfect ecosystem. During the rapid development of commercial whaling in the 20th century, more than 300,000 blue whales were killed, but the number of krill did not increase due to the sharp decline in the number of blue whales. Instead, the number of krill also dropped sharply. The reason is that with the decrease in blue whales, the number of phytoplankton has dropped avalanche-like, so the number of krill has also decreased accordingly.