What is Cnidaria?
Cnidaria is a phylum or scientific classification involving about 9000 species of animals that mostly can be found on water. Animals that belong to this scientific phylum or class are called “cnidarians”. Cnidarians have distinct cells called “cnidocytes” which are mainly used for catching prey. Most members of the Cnidaria phylum have jelly-like bodies like the common jellyfish known to people. Other animals belonging to this group include corals, sea pens, hydras, and sea anemones. For some people, some members of the Cnidaria phylum may seem to look more like plants but are actually animals that have similar structures to other “common” animals like fishes, birds, reptiles, and mammals. What may seem as leaves of a sea plant may actually be tentacles that perform the function of hands to catch food and prey.
There are four main groups of animals that belong to the Phylum Cnidaria. The first group is called Anthozoa which include the corals and sea anemones. Another group is called Scyphozoa and this group is referred to as the “swimming” group since its members are able to swim on the water. A typical member of this group is the jellyfish. Cubozoa is another group with the box jellies as examples and members. The last group of Cnidarians is called Hydrozoa and this group includes a very diverse collection of sea creatures and forms.
Most members of the Cnidaria group eat plankton and other animals to survive. Others prey on several parasites that come close to them while some cnidarians get their food from a type of algae called “endosymbiotic algae”. And since many of the Cnidarians are relatively small in size, they are also eaten by other animals like fish, turtles, starfishes, and sea slugs.
Cnidarians also grow in various parts of the water. Some animals like corals typically grow in warm and shallow waters while others are able to survive deeper waters, the cold seas in the Polar region, and even freshwater.