When it grows up, it eats the brain and turns into a plant. Why does the tunicate hate itself so much?

If we say that "survival" and "reproduction" are the two most important things for living things, there will definitely be people who object.

Because for humans, thoughts and consciousness seem to be the most important. If we are asked to abandon our own consciousness in exchange for the ability of immortality, I believe no one will do so. But animals are different. In order to survive and reproduce, they are willing to make all sacrifices. The tunicate is a marine animal. The reason why we know it is an animal is that it tastes really good and often appears in seafood markets as a "sea pineapple". If not, we would definitely mistake them for plants, because the tunicate always stays motionless on the reefs on the seabed, and looks like a flower. The tunicate looks like a plant, but it was not like this from the beginning. In its infancy, it is a real animal.

The tunicate is not only an animal, but also a relatively advanced animal.

Mammals, represented by humans, are the most advanced life forms on Earth. Mammals belong to vertebrates, and vertebrates belong to the Phylum Chordata, which means that the Phylum Chordata is the most advanced type of animal on Earth. In addition to the subphylum Vertebrata, the Phylum Chordata also includes two subphyla, namely the subphylum Cephalochordata and the subphylum Urochordata, and the tunicate belongs to the Urochordate. Unlike vertebrates, cephalochordates and tunicates do not have a spine, only a notochord on the back. The difference between cephalochordates and tunicates is that the notochord of cephalochordates accompanies them throughout their lives, while the notochord of tunicates only exists during the larval stage, which is the case with tunicates.

Sea squirts are hermaphroditic animals that have two modes of reproduction: sexual and asexual.

The asexual reproduction method of tunicates is very similar to that of plants. Adult tunicates will grow small buds, which gradually grow into a new tunicate. Since tunicates have such a convenient asexual reproduction method, why bother with sexual reproduction? Because the asexual budding reproduction of tunicates can only last for one generation, tunicates born through budding cannot continue to bud, and must reproduce sexually to produce new offspring. Compared with budding reproduction, the sexual reproduction of tunicates does take a lot of effort, because although they are hermaphroditic animals, they cannot fertilize themselves, which means that in order to reproduce offspring, there must be two tunicates.

Newly born tunicates are similar in appearance to tadpoles, but are much smaller in size, with a body length of only about half a millimeter.

Most metamorphic organisms grow more complex as they grow, but sea squirts are the opposite. These newborn sea squirts are much more powerful than their parents, with a well-developed notochord in their tails, which allows them to move freely. However, the young sea squirts do not cherish this ability to move freely. A few hours after birth, they will get bored with this ability, so they will look for a place to attach themselves. Once they successfully attach themselves to the reef, they will become a lifelong nail household and quickly begin metamorphosis. The metamorphosis of sea squirts is a huge physical transformation, which will not only greatly change the appearance, but also change the inside of the body beyond recognition.

Once the tunicate successfully attaches itself, it will not move for the rest of its life, so many organs, both inside and outside the body, become useless.

As a result, these useless organs will atrophy, and other organs that are retained will also change their positions and angles, with some organs even being able to rotate up to 180 degrees. After metamorphosis is complete, the tunicate is considered a true adult, and it becomes like its parents, without the ability to move. Regardless of whether an animal can move or not, it must eat to survive, and the food of the tunicate is plankton in the sea, but the tunicate, which cannot move, has no way to actively hunt and can only wait for others to feed it, and the flowing seawater acts as the tunicate's keeper. It can be seen that whether the tunicate can eat, and whether it eats a lot or a little, is a random thing.

Since we cannot control the matter of "eating", we must find ways to reduce the body's energy consumption.

In animals, the organ that consumes the most energy is undoubtedly the brain. Adult tunicates have no ability to move, and even have to wait for others to feed them. What's the use of a brain? Just eat it, so the tunicate's brain is absorbed by itself. Without a brain, the body's energy consumption is significantly reduced, and the tunicate can live heartlessly in the sea. For tunicates, "heartless" is not just an adjective, but a skill, because when they are in danger, they can spray out their internal organs, and marine fish will basically flee when they see this scene. The tunicate that sprays out its internal organs will not die. It only takes 12 days for them to have a brand new set of internal organs.

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