Chondrichthyes

Author:Laura Martin
__**EXAMPLES**__: [|Great white shark], //Carcharodon carcharias//

Spotted ratfish, //Hydrolagus colliei//

__**HABITAT**__:
 * They live in salt water, and have a wide range, including bays and estuaries, reefs, sand and mud.
 * They live in anywhere from 1 - 640 meters depth.
 * Chimera live in deep water, below 2,600 meters

__**TYPE OF COELOM:**__
 * Chondrichthyans posses a true coelom, meaning the mesoderm completely lines body cavity.
 * This allows for freer body movements because outer wall can move separately from enclosed organs.


 * __ENDOSKELETON or EXOSKELETON__:**
 * Chondrichthyans have an endoskeleton made completely from cartilage, thus their being called cartilaginous fish.


 * __TYPE OF NERVOUS SYSTEM__:**
 * Chondrichthyans have myelin sheaths around the axons of their neurons.
 * This permits much more rapid transmission of nerve impulses.
 * They also have a single, hollow, ectodermal, dorsal nerve cord with a large anterior end ( which is the brain).
 * They have three main sections to their brains, one which in controls ability to smell, another which is responsible for vision, learning, and motor responses, and the last which coordinates movement, muscle tone, and balance.

__**FEEDER**__:
 * The phylum chondrichthyes consists of fish which have well developed jaws. This allows for a larger range of food, and predation, but there are some filter feeders as well.

__**SYMMETRY**__:
 * Chondrichthyans have bilateral symmetry – only one plane creates two roughly symmetrical halves.
 * This is evident in their paired fins, nares, and gills.

__**REPRODUCTION**__:
 * Chondrichthyans reproduce by internal fertilization
 * This is in order to protect young from highly hypertonic environment, since they do not have the ability to survive in the salty water until later

__**CIRCULATORY SYSTEM**__:
 * Chondrichthya have a two-chambered heart
 * Blood travels through atrium, ventricle, to gills, through rest of body, and back to heart

__**ENDOTHERMIC or EXOTHERMIC**__.
 * Exothermic, but better described as ectothermic, as they use external means to lower and raise their body temperatures

__**SEGMENTATION**__:
 * Body segmentation is present, allowing for specialization of body parts

__**WORKS CITED**__: "Chondrichthyes." //Cyber Haus Computer Consulting, Web and Book Publishing//. Sci Links, 2000. Web. 28 Mar. 2011. <[]>.

Goss, Terry. "File:White Shark.jpg." //Wikipedia, the Free Encyclopedia//. 2006. Web. 28 Mar. 2011. <>.

Snook, Linda. //Hydrolagus Colliei//. 2004. Photograph. //Wikimedia Commons//. 13 Apr. 2007. Web. 28 Mar. 2011. .

Waggoner, Ben. "Chondrichthyes: Life History and Ecology." //UCMP//. Berkeley, 2006. Web. 28 Mar. 2011. <[]>.

Wikipedia. "Chondrichthyes." //Wikipedia, the Free Encyclopedia//. 24 Mar. 2011. Web. 28 Mar. 2011. <[]>.