Oceans make up about 71% of the Earth's area and have an average depth of about 3,795 meters. The ocean contains more than 1.35 billion cubic kilometers of water, accounting for about 97% of the total water volume on the earth has a huge living space, in this space, human beings can not normally move, but there are many mysterious spirits - fish live in this wonderful space, some of them are strange shapes, some are beautiful and moving, fish are the most closely related to people's lives, they are also one of the main inhabitants of the ocean, swimming freely in the blue sea, bringing infinite vitality to the sea. Let me introduce you to these underwater elves:
1. Lamprey eel (round mouth): also known as eight-eyed eel, seven stars, small brittle bones, is an ancient animal of the round mouth, lamprey eel order, but also an intermediate point in the evolution of invertebrates into fish, it can be regarded as a fish, but can not be regarded as a real fish. It is characterized by a cylindrical mouth, no upper and lower palate, and sharp teeth inside the mouth.
Lamprey
2. Hagfish (round-mouthed family): A general term for about 30 species of marine fish-shaped primitive vertebrates in hagfish. Hagfish, an inferior notochord creature. Hagfish generally live below 100 meters above the surface of the sea, with a white body, slender body like a snake, a mouth like an oval suction cup, and sharp yellow teeth inside. There are as many as 6 pairs of gill sacs in hagfish, hermaphrodite, but the sexes are still separated in physiological function, in the larvae of the hagfish, the anterior part of the reproductive glands is the ovary, the posterior part is the sperm nest, if the front end is developed and the posterior end is degenerated, it is female; conversely, it is male. Hagfish generally feed on tiny crustaceans or plankton. However, hagfish also feed on fish, often by the gills of the fish into the fish, in the stomach to bite the internal organs and muscles, only the skin and bones of the fish, and eventually bite through the abdominal muscles, holes out.
Hagfish
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