The phyla athropoda contains a huge amount of diversity. There are more species in this phyla than in all of the other phyla combined. Athropods are bilaterally symmetrical with segmented boides. Segmentation affects the internal and extrernal structures. The bodies of Athropods are covered with an exoskeleton made up of chitin, lipids and other proteins. Arthropods grow by molting their exoskeleton. Arthropods have a coelom with a much smaller volume than other organisms. It is usually only filled with reproductive and sxcretory systems. The mojority of the body cavity is an open space filled loosely with tissue and blood. The circulatory system is open and consists of a heart, arteries, and the open spaces of the body cavity. The gut is complete with a mouth and anus. Resperation takes place throught the bodies surface, gills, tracheae, or book lungs. The nervous system is similar to annelids. They have a brain and a nerve ring that connects the brain to the ventral nerve and rest of the body. Arthropoda reproduce sexually. In the majority, fertilization is internal. Many lay eggs and development proceeds with metamorphosis.
Beach Wolf Spider (Arctosa Littoralis)
Myers, P. 2001. "Arthropoda" (On-line), Animal Diversity Web. Accessed March 01, 2011 http://animaldiversity.ummz.umich.edu/site/accounts/information/Arthropoda.html.
