How do animals solve their own physiological problems?

There used to be a saying that in the animal world, only dolphins, pigs and some primates can enjoy the "pleasure" of sex, and other animals just want to reproduce. However, in fact, for animals, what is "pleasure" has not yet been scientifically explained. This is like Zhuangzi once said, "You are not a fish, so you can know the happiness of a fish?" In this regard, the Danish Animal Ethics Association once commented that reproduction can be understood as a reason for animals to have sex, but it is not the only reason. We can think that animals have sex because of "instinct", but the process of sexual intercourse will give them a positive feedback and make them more willing to do this behavior. Therefore, for this so-called "positive feedback", animals have tried their best. Animals can also do DIY. It has been mentioned in many reports that many animals masturbate in various forms, regardless of men and women, no matter when they have a spouse or not. More representative is the "stallion" of the racecourse. As stallions whose duty is to have sex, they don't forget to consolidate their work in their spare time: they will rub railings with their friends or directly beat their stomachs with that thing. Besides, don't be unwilling. I'm sorry if you tried to stop it. People will definitely respond to you with more violent masturbation! Dude, don't you think it's too tight? Not only horses, elephants, sheep, camels, ferrets and many other animals will touch their genitals with claws or other objects to make themselves "cool". Elephants used to know how to masturbate. Among all these masturbating animals, orangutans and monkeys are the most advanced: they can make their own "masturbation devices" with branches or stones, which can be described as real DIY masters! But then again, many animals masturbate because their activities are limited in captivity. Primates, in particular, will do almost anything out of boredom, which is actually very sad ... animal oral sex and Ig Nobel Prize. Besides masturbation, animals will do many new things, such as oral sex. I believe everyone knows the extraordinary research on bats in this year's Ig Nobel Prize, right? According to Dr. Zhang's discovery, dog bats will extend their mating time by oral sex. Besides, they do oral sex backwards ... actually oral sex is not completely accurate. Bats just lick the penis, and there is no piston movement between the mouth and penis, but licking the penis can also be regarded as one of the forms or actions of oral sex. Bats are really flexible. In view of this behavior of dog bats, Dr. Zhang put forward three hypotheses: one is stimulation, the other is lubrication, and the third is cleanliness. However, it is difficult to prove by experiments at present, and we can only stay on the hypothesis for the time being. Bad things about animals When it comes to sex, there are always some bad things, and so is the animal world. As the worst thing, pornography is naturally loved by some animals. A study by Duke University in the United States found that male monkeys would rather give up their welfare (such as extra bananas and juice) and watch photos and videos of female monkeys' buttocks. In addition to monkeys, keepers have been "teaching" giant pandas to have sex by showing them porn (panda's, of course, not human's). In addition to watching movies, some animals also make a profit by selling themselves. Monkeys are one of them, but even more surprising are "pure" penguins … these flightless birds need some pebbles as building materials when building their nests. Researchers at the University of Otago in New Zealand have found that there are always lazy girls who have sex with male penguins in exchange for pebbles for nesting. This is definitely a profitable behavior for the female penguin. As long as they wait in place and are attractive enough, there will be endless "stones" flying by themselves. ...