Phylum Cnidaria

Cnidarian organisms have one digestive opening that works as both the mouth and anus. They have tentacles around the opening help to catch its food. Cnidarians can do this by stinging or shooting out barbs once their hair like sensors on the tentacles go off. Main prey include shrimp and plankton.This opening leads to a cavity called the Gastrovascular Cavity. This is used to both digest food and transport nutrients. Cnidarians also posses a inner layer of canals used mainly for digestion, ingestion, and excretion. This layer is called the gastrodermis. 

 

Unlike most organisms, cnidarians do not have a centralized nervous system. Instead, they have organized nets of nervous the cover their body. Some cnidarians ,like jellyfish, posses advanced nerves that allow for more complicated responses such as more complex movement patterns. Furthermore, cnidarians also do not have certain tissues. They do not have true muscle cells but rather fibers that move together.

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Cnidarians posses the ability to move at least once in their lives. In the adult stages of Polyps they cannot move. Although, in larvae stages, Polyps have to ability to move around until they find a good environment to live in. The other form, Medusa, can move around through all stages of life. They move around by using contracting fibers located the the bottom of their bell.  

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Reproduction for cnidarians is a short process. Adult cnidarians, of certain species, release ova and sperm into the water during the breeding season for sexual reproduction. Cnidarians can also reproduce asexually. They do this with fragmentation, creating new living beings from broken off parts of their own.