General

Cnidarian



Jellyfish: Example of Cnidarian

What they are - biological definition

Cnidaria are relatively simple animals that live in aquatic environments, especially at sea (about 99% live in marine water and 1% in freshwater).

There are currently about 10,000 known cnidarian species.

Main characteristics of cnidaria:

- Epidermis composed of a layer of muscle fibers.

- They have no respiratory system. Breathing is aerobic, with each cell exchanging gas with the medium through the diffusion process.

- Have tentacles in the mouth, which is attached to a digestive cavity. Extra digestion occurs within the cell.

- Have radial symmetry.

- They have no circulatory system.

- They do not have excretory system. The elimination of waste (excreta) in water is done by cells through the diffusion process.

- The nervous system of the cnidaria is diffuse and composed of a network of nerve cells.

- In general, they can switch between polyp form and free form during their reproductive cycle.

- Cnidaria are carnivores. They capture their prey using the tentacles. They feed on sea worms, crabs, protists, fish and other cnidaria.

Examples of cnidaria:

- Jellyfish

- Jellyfish

- Sea Anemones

- Caravels

- Soft Corals

- Freshwater Hydras

Scientific classification:

Domain: Eukaryota

Kingdom: Animalia

Phylum: Cnidaria

Cnidarian classes:

- Anthozoa

- Scyphozoa

- Cubozoa

- Hydrozoa

- Staurozoa

- Polypodiozoa

Sea anemones: example of cnidarian animal.