Sloth: As long as I'm slow enough, the predators can't see me! When 'slow' becomes a talent

Review expert: Ran Hao

famous popular science writer

Surrounded by reinforced concrete, most of our understanding of nature since childhood came from TV shows. With the classic opening remarks by Mr. Zhao Zhongxiang: "Spring is here, all things are revived, and it's the season of animal mating... All things begin to be restless", the fantastic "animal world" once again greeted our eyes.

The agile leopard chased the antelope, and at that time really sweated for the antelope; the crocodile ambushed in the water, secretly observed the zebra group that was drinking water, and waited for an opportunity to attack, but the zebra was also very alert, once it found any danger, Just run away. In nature, "going for the best" seems to be the most used life-saving strategy.

This strategy is definitely a housekeeping skill for animals that run fast, such as antelope, zebra, hare, ostrich and other animals. But don't forget that there are some animals that are always "half a beat" and want to run when they encounter a predator? That is to be killed directly. So how do these slow-moving animals survive when they encounter predators? Today, the editor will introduce to you several well-known "chronic children".

The "veritable" sloth

When you see the name of the sloth, you basically know the characteristics of this animal: they live in trees and are very "lazy".

The biggest threat to sloths is the horned eagle. Rory Wilson, a biologist at Swansea University in the United Kingdom, once said: "They are powerful eagles with the most terrifying claws and terrifying beaks. Faced with them, sloths have little hope of survival. nothing."

However, looking at the monkeys running around in the forest, the sloth turned his head and smiled slightly, thinking that as long as I was slow enough, the horned eagle would not be able to see me.

Indeed, as long as the sloth is slow enough and with the blessing of the protective color, no matter how good the eyesight of the eagle is, it is not easy to find the sloth hidden in the woods.

Speaking of camouflage, sloths are masters, and they are naturally equipped with a "Geely suit" (click to learn about Geely suits). That's because a sloth's hair is a breeding ground for numerous microbes and algae.

A study of sloth hair shows that almost every hair of sloths is folded in half, and this structure forms a growth paradise for a variety of algae, which scientists do not rule out are also beneficial to the sloth's health.

In the sloth's body, especially the longer hair on the head and neck, some algae also grow, and "inhabit" some small insects that live in symbiosis with the sloth, such as sloth moths, which are decomposed by microorganisms after death Can be used as food for algae.

And these algae and microorganisms are the best equipment for sloths to "stealth" in the canopy. Wild sloths are basically green. So scientists speculate that the main reason sloths are so fond of the algae and microbes that live in their fur is for camouflage.

In addition, sloths are extremely slow-digesting animals.

A sloth's stomach is twice as large as that of an animal of the same size and accounts for 1/3 of its body weight. The process of digestion and absorption of food through the stomach and intestines is extremely long. A study shows that it takes up to 50 days for food to enter the sloth's mouth and finally excrete it, and it really explains the slowness of the property very thoroughly.

This characteristic of finding ways to completely drain the food nutrients also reduces the risk of sloths being preyed on during the foraging process.

The editor imagined that the taste of sloths with "grass" would not be very good, but I don't know what their natural enemies, horned eagles and jaguars, think.

"Regeneration Master" starfish

The well-known star of "SpongeBob SquarePants" is a bulky, silly-looking "optimist". And its prototype, the sea star that lives on the seafloor, although slow, is still very alert when facing predators.

What do slow-moving starfish walk on? We must first understand the structure of starfish.

Most of the starfish are in the shape of a five-pointed star, with five arms extending out from the central disk, but there are also more arms, such as the sun starfish, which generally has 10 to 15 arms.

The ventral side of the wrist has a step belt groove, and 2 to 4 lines of canal feet protrude from the groove. The tube feet are formed by the end of the sac on the water tube system of the starfish. The water tube system is filled with liquid. When the starfish moves, these structures are equivalent to a set of hydraulic devices. The movement of the starfish in the sea depends on the coordinated contraction of the tube and other parts of the water tube system. realized.

Although it has a lot of tube feet, it is not easy for the starfish to run when facing danger. But it possesses another powerful survival skill - limb regeneration.

The starfish has a very strong regeneration ability. A wrist with a little part of the central body disc tissue can regenerate a complete individual, especially with the sieve plate (the circular small plate at the edge of the central disc, which is the connection between the water pipe system and the outside world. connection) is easier to regenerate.

There is also a kind of finger starfish (Linckia), only one wrist tissue can regenerate the central disc and other wrists, but the size of the regenerated parts will be smaller than normal.

In this way, in the event of danger, the starfish can cut off its wrists on its own, attracting the attention of natural enemies, and then escape. Anyway, you can grow a new wrist. This powerful regeneration skill of starfish is reminiscent of Wolverine, one of the superheroes, and its strong healing ability makes Wolverine invincible.

Not only can starfish cleverly escape predators, but it is also a formidable predator, preferring to prey on bivalve mollusks such as oysters and mussels. Starfish have two stomachs (cardia stomach and pyloric stomach). When encountering prey, they spit out the cardia stomach, slowly corrode the prey with digestive juice, and then retract the stomach.

In addition, the red eye spot at the end of the starfish's wrist is a photoreceptor, and with the chemoreceptors around it, it can quickly find its prey in the water.

Although slow, but with so many stunts, starfish surviving in the sea with many predators is not a problem.

The "self-baptizing" hedgehog

Everyone is familiar with hedgehogs. Its biggest feature is that it is covered with short and dense thorns all over its body. Some people may ask, even if the hedgehog moves slowly, it is a "sharp weapon", and it does not pierce the predator to escape?

Indeed, a hedgehog's thorns are its best weapon. When threatened, it will curl up to form a thorn ball, wrapping its soft abdomen and limbs in it, and erect its thorns like a mammy. "Needle". Generally, small animals that are not strong in combat see such a big thorn ball, let alone nowhere to talk, it is difficult to get close.

However, most of the hedgehog's natural enemies are carnivores such as skunks, owls, and foxes. They are not vegetarians, and there are various methods to make the thorny hedgehog submit. For example, the skunk will look for the gap on the thorn ball and "fart" at it, and the hedgehog will stretch its body after being paralyzed.

Also, unlike sloths, hedgehogs can stay in trees all day in camouflage to reduce danger on land, where they need to forage for food. Hedgehogs are nocturnal and mainly feed on insects. However, when it slowly wanders and looks for insects seriously, it is likely to be crushed to death by fast-moving vehicles, which is not uncommon. It can be seen that the slow action of the hedgehog still brings a certain threat to its survival.

However, hedgehogs have a way of "self-baptism" that allows them to escape predators. This is the "smearing behavior" of hedgehogs. After chewing some plants in the surrounding environment, they smear each thorn on their face, abdomen and back with sap mixed with sap to make it consistent with the surrounding environment. The environment maintains the same odor to act as a "stealth" to prevent predators from finding out.

Another function of smearing is to smear some poisonous substances on their spines. If a natural enemy attacks, the poison on the spines also adds a layer of protection to the hedgehog. The venom of the hedgehog is applied to its own spines, and the hedgehog itself is quite resistant to the toad's poison and will not hurt itself.

It's actually hard to imagine how a hedgehog licks every thorn with its tongue, after all, just like it's hard for us humans to see our backs without looking through a mirror. So the editor has been wondering about the ability of hedgehogs to paint thorns until I saw this picture.

Some people who keep hedgehogs as pets will have a confusing behavior, that is, if they are bitten by their own little hedgehogs, they will not be angry but very happy. The reason is that they think that the hedgehog bites itself to paint the thorn, that is, to accept the taste of the owner. In fact, it is not, the hedgehog may bite you because it is frightened by you! If you are bitten by a small animal, timely disinfection is the most important thing. Don't be silly.

Finally, I would like to commend this small mammal with thorns all over its body. They like to eat insects. They can eat more than 200 insects in one night, and they have removed a lot of pests for agriculture and forestry. They are good friends of mankind.

Slowness of action does not allow some animals to have agile escape skills, but in order to survive, these "chronic" animals have evolved clever countermeasures to avoid predators. So what other tricks do you know of "chronic" animals to avoid predators?

The article comes from Baijiahao Beijing Science Center