Life originated in the primitive ocean, and the earliest vertebrates were also born in the waters. Both armored fish and placoderm fish once flourished in Earth's waters, but they soon withdrew from the stage of history. There are many factors that contributed to their extinction, but the main reason may be the rise and development of early higher fish. Higher fish, which are what each of us call fish in our daily concepts, have such perfect ability to adapt to aquatic life that their existence can be found in almost every corner of the waters on the earth. The vastness of the sea means that fish can jump across this An idiom truly expresses their evolutionary success.
Shark - a cartilaginous fish
There is an idiom in China - Hufu riding and shooting. It refers to the fact that during the Warring States Period, the Chinese people in the Central Plains always wore long robes with long sleeves because they respected etiquette. When they had a war with the nomadic Hu people in the north, Then he fights on a horse-drawn chariot. Therefore, they appear to be cumbersome and inflexible in action. On the contrary, the Hu people wore short and lean clothes, ran around on fast horses, were very flexible, and could shoot arrows accurately while riding on horses. As a result, the clumsy Huaxia people always suffered losses in battles with the barbarians. Later, Zhao, one of the Chinese tribes, carried out reforms and learned from the Hu people's habit of wearing short clothes and their ability to ride horses and shoot arrows. As a result, the combat effectiveness of the army was greatly increased.
Compared with placoderm fish, one of the most important progressive traits of higher fish is simply a story of "riding and shooting in wild clothes" in the animal kingdom. Higher fish no longer have various bone armors that are integrated or large, heavy and inflexible, but replaced by various small scales that can move flexibly between each other, which makes their movements flexible. Sexuality is greatly enhanced.
Seahorse - a bony fish
Among the many progressive traits of higher fish, there is one innovation in anatomical structure that is very important. In the early stages of fish evolution, the first pair of gill arches behind the jaws were specialized into the lingual arches, and the upper bones were specialized into the hyoid mandibles, which serve as supports or connections, connecting the jaws with the skull (the bones that wrap and protect the brain). )connect them. The hyoid jaw played an important role in the evolution of fish and the development from fish to terrestrial vertebrates. Since one end of the tongue and jaw is connected to the back of the skull (i.e., the skull) and the other end is connected to the jaw, the gill slit originally located between the skull and the lingual arch is greatly reduced. In more primitive fish, it becomes Blowhole, in highly advanced fish it completely disappears.
Higher fish include cartilaginous fish (class).
animal tags： seahorse
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