ROTIFERA
DESCRIPTION
Rotifera are found in abundance in freshwater. These are also known as wheel animalcule. These are the most minute animals of Metazoa. The body of these animals is transparent and inner body activities can be observed form outside in living state.
These animals were discovered by Leeuwenhoek (1703). Initially, they were placed in protozoa groups. Ehrenberg, (1838) placed them separately in class infusoria. The word Rotifera has been originated from two Latin word rota(meaning: wheel) and ferre(meaning: to bear). Hence, Rotifera means wheel bearers.
These animals were named because the cilia present on the disc-shaped lobes on their head move in sequence giving the impression that a wheel is moving on their head.
Main features of Rotifera are-
(1) They are microscopic animals.
(2) Body is unsegmented.
(3) Bilateral symmetry is found.
(4) These are free-floating animals in which a ciliary apparatus known as corona, is present at the anterior end which helps in locomotion and feeding.
(5) There is a muscular pharynx which has movable jaws.
(6) Excretion occurs through flame bulb nephridia which directly open in cloaca.
(7) There is no any separate organ for respiration and fluid circulation is found.
(8) Male and female sexes are separate and Structurally different. In this way they are dioecious and there is sexual dimorphism in them.
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