Rotifera

Author: Cele Fryer

 * __**EXAMPLES**__:
 * [[image:file://unit10animalevolution.wikispaces.com/C:/Users/11frycec/AppData/Local/Temp/moz-screenshot-7.png]][[image:asplancha.jpg width="270" height="203" caption="Asplancha"]]
 * [[image:conochilius.JPG width="254" height="186" caption="Conochilius"]]

__**HABITAT**__: The habitat of rotifers may include still water environments, such as lake bottoms, as well as flowing water environments, such as rivers or streams. Rotifers are also commonly found on mosses and lichens growing on tree trunks and rocks, in rain gutters and puddles, in soil or leaf litter, on mushrooms growing near dead trees, in tanks of sewage treatment plants, and even on freshwater crustaceans and aquatic insect larvae.

__**TYPE OF COELOM:**__ Rotifers (Rotifera) have a body cavity (coelom) where organs are found and that can serve as a hydrostatic skeleton. Their coelom is called a pseudocoelom because it is not completely lined by mesoderm.


 * __ENDOSKELETON or EXOSKELETON__:** Hard exoskeleton formed by a cuticle and must be molted. Different rotifer species display a striking variety of body forms and the morphology of individuals may be further altered, for example by growth of spines, in response to ecological cues indicating the presence in the environment of particular types of prey or predators**.**


 * __TYPE OF NERVOUS SYSTEM__:** Rotifers have a primitive eye cup, like the flatworm, and other primitive senses tied into a rudimentary brain

__**FEEDER**__: They can be either sessile suspension feeders, filtering out tiny protozoans and algae, and bits of detritus, or raptorial, animals that actively pursue their tiny prey.

__**SYMMETRY**__: Rotifers have bilateral symmetry and a variety of different shapes. The body of a rotifer is divided into a head, trunk, and foot, and is typically somewhat cylindrical. There is a well-developed cuticle, which may be thick and rigid, giving them a box-like shape, or flexible, giving the animal a worm-like shape.

__**REPRODUCTION**__: They only reproduce sexually, and have separate sexes. Most are parthenogenetic, unfertilized eggs can develop directly into female adults. They copulate by means of "hypodermic injection". Most rotifers are oviparous, releasing eggs outside their bodies, but a few are ovoviviparous, retaining the embryo inside the body until it hatches.

__**CIRCULATORY SYSTEM**__: Rotifera have no respiratory and no circulative system. It is believed that gas is taken up through the ingested water and the spacious body cavity.

__**ENDOTHERMIC or EXOTHERMIC**__. Rotifers are unable to regulate their own body temperature internally and must rely on the external environment to provide them heat. Thus, they are exothermic.

__**SEGMENTATION**__: The series of rings, which make the body appear to be segmented, are in reality zones of folding of the gelatinous cuticle. There is no true segmentation in rotifers.

__**WORKS CITED**__:

"Phylum Rotifera Example | Reference.com." //Reference.com | Free Online Encyclopedia and Library Information//. Web. 28 Mar. 2011. . "Rotifera - Encyclopedia of Life." //Encyclopedia of Life//. Web. 28 Mar. 2011. . "Rotifers - Phylum Rotifera." //Angelfire: Welcome to Angelfire//. Web. 28 Mar. 2011. . "The Rotifers (Phylum Rotifera)." //The Earth Life Web//. Web. 28 Mar. 2011. .