Speaking of sloths, everyone should be familiar with them, from Sid the sloth in the Ice Age to Lightning the sloth in Zootopia. However, the sloth in reality is much more dull than the sloth in film and television works, and is even praised by scientists as the "first sloth" in the animal kingdom.
How lazy are sloths? Sloths mainly live in the tropical rain forests of Central and South America, including three-toed sloths and two-toed sloths. The difference is mainly based on the number of toes on their forelimbs. Although they are more similar in appearance, in fact, these two sloths did not evolve from the same ancestor. Their appearance and behavior are so similar, which is the result of convergent evolution. Simply put, everyone is so lazy, so they all become like this.
Just like fish can't live without water, sloths have the word "tree" in their names mainly because they live in trees most of the time. As long as there are leaves on the tree to eat, they will not leave the tree. Some sloths even live in trees all their lives. And they only eat leaves, unlike monkeys who eat fruits and nuts to supplement energy. The sloth eats leaves all its life, even only the leaves of a tree.
Zoologists believe that sloths are the only animals that have evolved reversely on this earth, that is, unlike other animals, they always develop in the direction of improving speed, alertness and responsiveness in the long evolution process; Instead, it becomes more and more clumsy and slow.
So how slow are they? Everyone knows that snails crawl slowly, but researchers have observed that sloths are slower than snails. A snail can move 48 meters per hour, which is equivalent to 2800 times its own length; The sloth with a body length of 53 cm moves 3-6 cm per second on average, and the converted hourly speed is 0. 109-0. 158 km, which is equivalent to 200-400 times its own length. This speed is not as good as slow sheep.
Because they run slowly, sloths are too lazy to run when they are in danger. Once found by natural enemies such as horned eagle, jaguar or leopard cat, they are basically playing with eggs. "Anyone in the forest can eat them." Sam Truell, one of the founders of the Costa Rican sloth research institute, said.
Lazy to the extreme, the secret of survival sloths are so lazy that anyone can bully them in the forest. So how did they survive in the crisis-ridden tropical rainforest and survive in such a nature of survival of the fittest for at least 30 million years? The reason is still because of the word "lazy".
Because of laziness, sloths are too lazy to find food. They only need a few leaves to meet their energy needs. However, leaves are difficult to digest and there is little nutrition, so exercise will be reduced as much as possible, and the metabolism of the body is extremely low. Their wild metabolic rate is 162 kJ/ day/kg, which means that any other mammal, including koalas (4 10 kJ/ day/kg) and giant pandas (185 kJ/ day/kg), is too lazy to be famous and needs more energy.
So they can exercise less in order to save energy, just as we drive to save fuel, slow down or even stop driving. Such a low metabolism means that it is difficult for them to keep their body temperature, so they can allow their body temperature to fluctuate up and down. Like reptiles, the brown-throated three-toed sloth can make the body temperature fluctuate by nearly 5℃. When the weather is good, it climbs to the top of the tree to bask in the sun, and when the weather is bad, it tries to move as little as possible, thus saving a huge energy expenditure.
Doing less exercise can not only save energy expenditure, but also have the advantage of not being easily discovered by predators. Even because I haven't moved for a long time, I have green algae on my body, just like a lucky suit, which is more difficult to be found. These green algae can not only be used as camouflage, but also resist the invasion of various fungi and germs, and are rich in lipids. So sloths can even eat two handfuls of green algae from themselves when they have nothing to eat. Animals that can grow vegetables on themselves and eat whatever they want are probably sloths.
The sloth is lazy, but his strength is not small at all. Because they hang upside down on the tree for a long time, they are motionless for a long time, extremely tough and durable, and extremely powerful. Even bodybuilders or muscular men who exercise regularly can't hang themselves on the horizontal bar for a long time, while sloths can hang upside down from trees and even sleep like this. Because of the crisscross tendons on their hands and feet, they can clench their fists even at rest. And their muscles contain an enzyme, which enables them to tolerate a large amount of accumulated lactic acid and help them resist the fatigue of hanging on trees for a long time or walking in super slow motion. Since everyone can live on a tree for a long time, why do sloths make such an incredible move of excreting under the tree?
Why should such a lazy sloth get off the tree and excrete? Most arboreal animals will choose to "drop" shit directly on the tree, but sloths will choose to come down from the tree every time they poop. For them who are slow and extremely energy-saving, this kind of behavior seems uneconomical, and it is also dangerous to excrete under the tree. It is said that more than 50% sloths died unexpectedly during defecation. So why do sloths insist on doing such "irrational" behavior?
The sloth eats leaves all its life, which are unpalatable and nutritious, so it takes a long time for the sloth to digest them. In order to digest these leaves, their stomachs are also big. They slowly digest these leaves through the bacteria in their stomachs, and then they can finally discharge almost completely drained fiber without nutrition through the long intestine. This process takes at least one month, so the sloth's poop accumulates quite a lot in the body, almost equivalent to one-third of the body weight.
It takes a lot of time to poop so much at once, so the sloth comes down from the tree every week, digs a hole under the tree with its stubby tail, then spends the night defecating and then covers it with fallen leaves. And every time I shit, I find the same pit, which is more delicate than a cat.
It was first suggested that they make friends by poop under the tree and let the beautiful female sloth know that there is a handsome boy living in this tree. But sloths woo by barking, so there is no need to risk excreting under the tree. In addition, there is a view that it is even less necessary to fertilize uncle when defecating under the tree, because "airdropping" on the tree can also play the role of fertilization, and there is no need to take risks and lose physical strength to do it.
Finally, a research team from the University of Wisconsin found that sloths actually do this by establishing a unique relationship with some moths on their bodies. There are all kinds of parasites in the hair of sloths. Some parasites can only be found in sloths, such as sloth moths. They all stare at the sloth and defecate once a week, because they need to lay eggs in the sloth's feces, and moths that have just hatched from eggs need to climb onto the sloth again through the sloth's defecation. How old can a sloth live? 120 lazy moth.
What good are these lazy moths to sloths? The researchers found that these sloth moths are related to the amount of nitrogen, phosphorus and algae in each sloth. The higher the density of sloth moth, the higher the concentration of inorganic nitrogen and the number of green algae in sloth hair. After the sloth moth dies, it can also become a fertilizer for these plant microorganisms and promote the growth of green algae. It is simply a "mobile ecosystem".
Laziness is one of the driving forces of human technological evolution, but no one wants to be a sloth, right? We don't lack energy, so we have time to walk and exercise more, which is the evolution direction of human beings.