Arthropods

Author: Emily Strickland
__**EXAMPLES**__: Crab (//Callinectes sapidus//) 

Arabesque Orbweaver Spider (//Neoscona arabesca//)




Spiny Shrimp (//Phyllognathia ceratophtalmus//)

__**HABITAT**__: Arthropods live in all different types of ecosystems. Because they make up approximately eighty percent of all living animal species, they inhabit both seawater and freshwater, land, and air ecosystems. Some of them even live underground

__**TYPE OF COELOM:**__ Arthropods have a coelom. A coelom is the cavity lined by membranes that contains the internal organs. Chordates are coelomates which means they have a coelom that is completely lined with mesoderm. The coelom of the arthropod is reduced to small areas around the reproductive and excretory system and is largely occupied by a cavity that runs most of the circulatory system.

Arthropods all have exoskeletons made of chitin.
 * __ENDOSKELETON or EXOSKELETON__:**

Arthropods' nervous system is described as "ladder-like", with paired nerve endings and chords running through the entire body. Their heads are formed by fusion of varying numbers of segments, and their brains encircle the esophagus.
 * __TYPE OF NERVOUS SYSTEM__:**

__**FEEDER**__: Arthropods have a representative in every type of feeder: carnivores, herbivores, omnivores. detritus feeders, filter feeders, parasites, etc.

__**SYMMETRY**__: Arthropods have **bilateral symmetry**. This means that the right halves of arthropods' bodies are mirror images of the left.

__**REPRODUCTION**__: There are males and females that together reproduce sexually; their reproduction is **hermaphroditic**, but some is **parthenogenic**.

__**CIRCULATORY SYSTEM**__: Arthropods have what is called an open circulatory system that has a dorsal heart and a system or arteries that transport blood which eventually drains into the pericardial sinus tissue surrounding the heart.  __**ENDOTHERMIC or EXOTHERMIC**__. Arthropods can be endothermic and exothermic.

__**SEGMENTATION**__: All arthropods are internally and externally segmented at some point in their lives. For some, they must grow into their segmentation.

__**WORKS CITED**__: "Arthropod (animal Phylum) :: Circulatory System -- Britannica Online Encyclopedia."// Encyclopedia - Britannica Online Encyclopedia //. Web. 01 Apr. 2011. . "The Arthropod Story." // Berkeley.edu //. University of California BerkeleyUniversity of California Museum of Paleontology, 22 Aug. 2008. Web. 01 Apr. 2011. . "Introduction to the Arthropoda." // Berkeley.edu //. University of California Museum of Paleontology. Web. 01 Apr. 2011. . .