Essay On Coelomates

A coelomate has a fluid filled body cavity, which is completely lined by the mesoderm. The organs of a coelomate are suspended within the fluid filled body cavity. This provides protection from any shock put on the organs. This fluid also provides shape to animals without a hard skeleton. Animals like Arthropoda and Echinodermata are examples of coelomates. Acoelomates lack internal cavities and fluid altogether. Their organs are located within the mesoderm which means less protected from shock or pressure. Aceolomates could also have a spongocoel which is the central cavity in a Porifera, a diploblastic organization with mesoglea like a Cnidaria, or a solid layer of mesoderm like a Platyhelminthes. Protostome development means that an organism develops a mouth first from the blastopore and anus second. In the early stage of development, the embryos undergo spiral cleavage, which mean micromeres between micromeres. The cells that formed are determinate, which means that the blastomere fate is established during the early stages of development. Animals like Platyhelminthes, Molluscs, and Arthropods are examples of some protostomes. Deuterostome development means that an organism develops anus first near the blastopore …show more content…
All radially symmetrical animals live in the water, Cnidarias are a good example of radial symmetry. Bilateral symmetry means that only one plane can pass through the the center of the organism and divide it into similar left and right sides. Bilateral organisms exhibit cephalization because when there is a front and end to an organism, it is helpful to have sensors in the front to know where to go. Majority of animals are bilateral and they live on both land and water. The Echinodermata is both radial and bilateral symmetric. It is bilaterally symmetric as a larvae but when it turns into an adult it becomes