1, protozoa
They are all single-celled animals, a few of them gather in groups, live in water or wet soil, some live parasitically, and have asexual or sexual reproduction. There are no species of medicinal animals in this phylum, but it is a primitive group in evolution and is closely related to human life. Some parasitic species will do great harm to human health and the reproduction of economic animals.
2. Sponges
Porous animals, also known as polypores, are the most primitive multicellular animals living in water. Although cells are differentiated, they do not constitute tissues. Cells can be arranged in two layers, but they do not differentiate into endoderm and ectoderm. There is a pipeline system in the body to get food from water, and bone needles support and protect the body. For example, the fragile needle sponge Sp0ngiLLa Fragilis can be used in medicine.
3. Coelenterata
Coelenterates, also known as echinoderms, have about 6.5438+0 million species, some of which live in fresh water, but most of them live in the ocean. The tentacles of coelenterates are very sensitive, and groups of stinging cells called stinging silk sacs are born on them. This kind of animals mainly include jellyfish, corals, anemones and corals.
4.[ Invertebrate] mollusks
Mollusks are the second largest group in the animal kingdom, with about 50 thousand species. Most mollusks have 1, two or more shells with different shapes outside their software. Common cephalopods, gastropods and bivalves.
5. Echinoderm
Echinoderms include more than 6,000 species in 5 classes, including starfish, sea urchins, sea cucumbers, crinoids and sea lilies.
Extended data
Zoology classifies animals with the same or similar characteristics into the same category according to their morphology, internal structure, embryonic development characteristics, physiological habits and geographical environment.
Mainly divided into two categories: chordates and invertebrates; According to aquatic or terrestrial animals, it can be divided into aquatic animals and terrestrial animals; According to whether there are feathers, it can be divided into feathered animals and featherless animals; According to whether there is a spine in the body, we can divide all animals into vertebrates and invertebrates.
After the appearance of primitive life, with the change of living environment, millions of species have appeared and died out one after another, and only those species that can adapt to environmental changes have survived and multiplied to this day. The process of continuous evolution of this species is biologically called evolution.
Baidu encyclopedia-animals