CNIDARIA
Examples: Sea Anemone, Corals, Jellyfish
There are over 10,000 different known species of Cnidaria. Almost all of the species are dipoblastic, which means in between two layers of cells, their is a non-living substance called mesoglea. This means there are only two layers of cells in contact with the water. There are four main classes of the phylum Cnidaria: Hydrozoa, which includes all fresh water species; Scyphozoa, is an example of a "true Jellyfish"; Cubozoa, such as a box jellyfish, which are infamously known for their brutal venom; Anthozoa, or corals and anemone. All species of the Phylum Cnidaria are equipped with nematocysts, which are stingers that are utilized to trap food and protect the organism.
There are over 10,000 different known species of Cnidaria. Almost all of the species are dipoblastic, which means in between two layers of cells, their is a non-living substance called mesoglea. This means there are only two layers of cells in contact with the water. There are four main classes of the phylum Cnidaria: Hydrozoa, which includes all fresh water species; Scyphozoa, is an example of a "true Jellyfish"; Cubozoa, such as a box jellyfish, which are infamously known for their brutal venom; Anthozoa, or corals and anemone. All species of the Phylum Cnidaria are equipped with nematocysts, which are stingers that are utilized to trap food and protect the organism.
CIRCULATORY SYSTEM
Cnidaria do not have a circulatory system simply because it is not needed; all cells are in contact with the water, which contains oxygen and nutrients. This is different from the Porifera phylum because Cnidarian species do not have pores. Instead the cells take in the oxygen directly from the water in contact with them. The cells undertake a process of diffusion to transport the oxygen, nutrients and waste in and out of the organism. Cnidaria have extensive digestive tracks which are responsible for the transportation of nutrients to the cells.