Phylum Rotifera
Major Attributes:
- Cylindrical with an anterior ciliated disk and posterior tail.
- Covered with a hardened cuticle.
- Microscopic at about 3mm.
- Anterior sensory antennae or palps.
- Complete digestive system.
- Parthenogenesis is common.
Discussion:
The Rotiferae consist of three classes, the Seisonacae,
Bdelloideae, and Monogontae. The Seisonaca has a small head and a long
neck. The foot of this organism is stalk-like with an adhesive disk. The
sexes are alike. The Bdelloidea also has an elongated body, but the head
and foot can be retracted. There is a mastax present and there are also
false cuticular joints. In the class Monogonota, the body is highly
variable and males are usually small. They are parasitic and usually
sessile.
Some Interesting Facts:
- An important predator in freshwater.
- Has a constant cell number.
- Toes secrete an adhesive.
Lab Directions:
There are two slides of rotifers, one labelled "rotifers" and the other
labelled Brachionus, a species of rotifer. How are these rotifers the
same as or different from the ones you saw when you were hunting for
tardigrades. You need only make a drawing of the whole rotifer, or better
yet, a drawing of the rotifer you saw when hunting for tardigrades.
Pertinent Books Found In Lamson Library:
- Buchsbaum, Ralph. 1976. Animals Without Backbones. Chicago:
University of Chicago.
- Hengner, Robert W. and Joseph G. Engemann. 1968. Invertebrate
Zoology. Toronto: Macmillian Company.
(Holly A. Crockett, Fall 1994; edited by Betty Miller, Spring 1995))