The main characteristics of coelenterates

Coelenterates belong to the phylum Cnidaria. It was called the Cnidaria in the past, and it mainly refers to cnidarians and arthropods. It has many characteristics. Such animals are generally carnivorous, their trunks are radially symmetrical, and most of them are aquatic animals. This type of animal generally has two reproductive methods, one is asexual reproduction and the other is sexual reproduction. Let us now understand the main characteristics of coelenterates.

The main characteristics of coelenterates

1. Most are carnivorous, and a small number of species obtain energy from photosynthesis of symbiotic organisms in their bodies. 2. Its trunk is radially symmetrical, it is aquatic, and most of them live in a fixed state.

3. The body wall is composed of two layers of cells, the epidermis and the gastrodermis, with a gelatinous mesogloea between them that plays a supporting role. 4. There is an intestinal cavity and a perioral part (Peristom), which is both a mouth and anus.

5. There are more than 20 species of cnidocytes, which contain nematocysts. The bristle-like protrusions at one end of the nematocyst cause the nematocyst to empty when stimulated. There are protrusions on the surface of the cnidocytes and a stick-like structure inside the cell body. The cnidocytes contain substances secreted by the gonadal body, which will be released under pressure. 6. Extracellular digestion in the intestinal lumen

7. Diffuse nervous system, in the form of a network. 8. Jellyfish have sensory organs that can sense light and gravity. 9. They can be hermaphroditic or heterosexual.

Reproductive methods

There are two types of reproduction: asexual and sexual. Asexual reproduction often forms colonies by budding. Sexual reproduction is mostly dioecious. The gonads of Hydrozoa are formed by the ectoderm, but the gonads of Scyphozoa and Anthozoa come from the endoderm, and the germ cells come from mesenchymal cells. Marine species have a planula stage during embryonic development.

The advanced features of coelenterates compared to porifera:

Coelenterates are low-level multicellular metazoans that have undergone significant evolution from the more multicellular parazoans, the porifera: (1) the cells have become more clearly engineered, with primitive muscle tissue and a nervous system, indicating that this type of animal has developed from the cellular level to the tissue level; and (2) in terms of phylogeny, it has progressed from a single-celled protozoa to a metazoan with a true two-germ layer. This was a major leap in the history of animal evolution.

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