What are Coelenterates? What are the representative animals of coelenterates?

Coelenterates are radially symmetrical, with two germ layers, tissue differentiation, primitive digestive cavity and primitive nervous system. Its main characteristics are: the body shape has a relatively fixed symmetrical form, and the body shape of this phylum is generally radially symmetrical.

Coelenterates can be divided into hydras, jellyfish, and corals.

Cnidaria is also known as Cnidaria, which used to be called Coelenterata, because its meaning applies to cnidarians and ctenophores, so it is mostly disbanded.

Scientific name in Chinese. Cnidarian phylum.

Latin scientific name. cnidaria

It is also known as the phylum Cnidozoa, the phylum Coelenterate.

kingdom Animalia. The status quo is now mostly abandoned.

Chapter 22 of the Beijing Normal University Edition of Biology Chapter 22 The Main Taxa of Animals (Invertebrates) Teaching Micro Lesson.

1. Sea anemone.

The sea anemone is a carnivore that grows in water, belongs to the cnidarians (coelenterates), and is a very simple animal with no central information processing mechanism, which means that it does not have even the lowest brain base.

2. Polyps. Hydras, coelenterates, have a cylindrical, brown body with tentacles around their mouth, are tools of predation, and have a cavity in their body. Multicellular invertebrates, including bud bodies, sperm nests, mostly found in the sea, a few species are produced in fresh water, attached to aquatic plants or dead leaves in ponds and marshes, ditches.

3. Polyps.

A general term for a variety of organisms in the class Coral. The body is cylindrical, with eight or more tentacles, and the tentacles have mouths. Mostly gregarious, combined into a group, it is a marine cylindrical coelenterate that feeds on the small plankton of the ocean, with food entering through the mouth and food residues excreted from the mouth.

Coelenterate morphological characteristics:

1. Muscles and movement.

Cnidarians are rarely able to do active displacement movements, and their ability to move is very limited, especially in the hydra type. Movement is caused by the contraction of myofibrils in epidermal muscle cells.

2. Feeding and digestion.

cnidarians are all carnivorous and feed on plankton, small crustaceans, polychaetes, and even small fish.

3. Respiration and excretion.

Cnidarians do not have special respiratory and excretory organs, because the body is composed of two layers of cells around the gastric circulation cavity, and through the mouth to make the gastric cavity communicate with the outside world, in fact, the two layers of cells on the body wall are in contact with the external environment, so respiration and excretion can be carried out directly and independently by the body wall cells.

The phylum Coelenterates can be divided into three classes, Hydras, Jellyfish, and Corals.

Hydroids: Most of the hydroids live in seawater, and the life history of most species has the phenomenon of generation alternation of hydrops and jellyfish. Representative species such as polyids, peach blossom jellyfish, monk's hat jellyfish, etc.

Jellyfish class: Jellyfish class Bowl jellyfish all live in seawater, most of them are large jellyfish, the hydra type is very degraded, and its jellyfish structure is more complex than that of the hydra class. Representative species such as the Xia jellyfish, the moon jellyfish, the jellyfish, etc.

Corals: Corals are all marine animals that live on the bottom of warm and shallow seas. There is only the hydrop type, and its structure is complex. Polyps can secrete calcareous exoskeletons, forming coral reefs and islands that form "underwater gardens". Representative species such as sea anemones, stony corals, red corals, etc.

Common coelenterates are: anemones, jellyfish, hydras, polyps, etc.

1. Jellyfish, also known as jellyfish, is mainly produced in the southeast coast of China. 8 In September, jellyfish often float on the surface of the sea in groups, sometimes being stranded on the beach by shocks, and when fishing, their umbrellas are pierced with long markers and then caught with nets.

2. Hydra (scientific name: hydra), a coelenterate, has a cylindrical, brown body, tentacles around the mouth, is a tool for predation, and has a cavity in the body. Multicellular invertebrates, including buds and testes, are mostly found in the sea, and a few species are produced in freshwater, attached to aquatic weeds or dead leaves in ponds and marshes, ditches.

3. Sea anemone (scientific name: actiniaria) is a carnivore that grows in water, belongs to cnidarians, an order of the subclass Coral Species, is a very simple animal with a very simple structure, no central information processing mechanism, that is to say, it does not even have the lowest brain foundation.