The amphioxus, which belongs to the cephalopod subphylum Gillostomatidae, has no vertebrae and is not a fish. Although the amphioxus is a small and insignificant animal, it is a transitional animal from the evolution of lower invertebrates to higher vertebrates, and is also a model of vertebrate ancestry. The functions of amphioxus, such as feeding and excretion, are like those of invertebrate forms, but the vascular system, respiratory system, nervous system and embryogenesis are all modeled after vertebrates.
The amphioxus is an animal adapted to the warm sea. It buries half of its lower body in the sand, with only the front end exposed, and during the day half of its body hides among the gravel, waving in the sunlight, relying on currents to bring plankton and diatoms and plants for it to eat, a passive feeding method.
Indicating its inferiority, that is to say, it is lower than the vertebrates in evolution; it is the active moment in the evening, when it leaves the sandy nest, like a feathered arrow off the string catapulted to the surface of the water activities, and once encountered disturbances, and swam back to the sandy beach nest. The amphioxus swims in a spiral fashion.
Expanded Information:
For the amphioxus, China classifies it as a second-class national protected animal. It belongs to chordates, feeding on diatoms and sea serpent-tail larvae, and inhabiting clean and breathable sea areas with coarse sandy seabed. Wenchang fish "Wenchang" two words, some people have proved that is derived from "Wenchang Emperor". According to Xiamen, "Tongan County" records: "Wenchang fish, like eel and fine as silk, produced in Xixi near the sea", commonly known as Wenchang Emperor's birthday only, so the name.
In the 19th century, the Russian embryologist Kovalevsky wrote a book "the developmental history of the amphioxus", which provided a strong basis for Darwin's theory of evolution, and Koch's research results were highly praised by Darwin. The main place of origin of amphioxus is Xiamen sea area in China, where a national amphioxus nature reserve has been built in 1991.
People's Daily Online - So many living fossils, Maoming's amphioxus resources up to 20.4 billion
Baidu Encyclopedia - Amphioxus