Intro
Cnidaria contains over 10,000 species. Exclusively they are found in aquatic or marine environment. They have specialized cells used for capturing prey called cindocytes. They have bodies consisting of a jelly like substance called mesoglea. There are two forms of Cnidaria. They are swimming medusae and sessile polyps. Many cnidarian species make colonies.They are coordinated by a decentralized nerve net and simple receptors. For a long time they used to be grouped with ctenophores in the phylum Coelenterata.Most Cindarians feast on organisms of many sizes. Anything from plankton to animals larger than themselves. They are often preyed upon by star fish, sea slugs, fish, and turtles.
Nervous System
Cnidaria have no brains or central nervous system. Instead they have a decentralized nerve net. They have sensory neurons that generate signals in response to stimulus such as odor. They have motor neurons that tell muscle to do various actions like to contract. They also have intermediated neurons that connect them all together. Cilia detect physical contact and nerves tell cindocytes when he smell of prey or an attacker is detected. Swimming colonies sense tilt by means of statocysts. Finally they have little eyes called ocelli which can detect which direction light is coming from.
Cnidaria contains over 10,000 species. Exclusively they are found in aquatic or marine environment. They have specialized cells used for capturing prey called cindocytes. They have bodies consisting of a jelly like substance called mesoglea. There are two forms of Cnidaria. They are swimming medusae and sessile polyps. Many cnidarian species make colonies.They are coordinated by a decentralized nerve net and simple receptors. For a long time they used to be grouped with ctenophores in the phylum Coelenterata.Most Cindarians feast on organisms of many sizes. Anything from plankton to animals larger than themselves. They are often preyed upon by star fish, sea slugs, fish, and turtles.
Nervous System
Cnidaria have no brains or central nervous system. Instead they have a decentralized nerve net. They have sensory neurons that generate signals in response to stimulus such as odor. They have motor neurons that tell muscle to do various actions like to contract. They also have intermediated neurons that connect them all together. Cilia detect physical contact and nerves tell cindocytes when he smell of prey or an attacker is detected. Swimming colonies sense tilt by means of statocysts. Finally they have little eyes called ocelli which can detect which direction light is coming from.
Anthozoa
Anthozoa is a class that consists of corals and sea anemones. They reproduce asexually and 6,100 species have been discovered. These Cnidaria dine on plankton and fish. Anthozoa can be subdivided in to two more classes called Ceriantharia and Antipatharia.
Medusozoa
Medusozoa, or more commonly known as jellyfish, are found in every ocean. They are the oldest multi organ animal in the world. Jellyfish do not have digestive, central nervous, respiratory, or circulatory systems. Jellyfish have ocelli that are like eyes but can not process images but can detect light and which direction it comes from.
Hydrozoa
Hydrozoa are very small, predatory animals. Some live solo while others live in groups or colonies. They are mostly found in salt water although some do live in fresh water. Some examples of hydrozoans are freshwater jellyfish, freshwater polyps, Obelia, etc.