rotifer - Structure and form, Reproduction

A microscopic aquatic animal with an unsegmented body typically covered by a horny layer which may be thickened into plates; lacks a muscular body wall; swims by means of a ring of beating hair-like structures (cilia) that resembles a spinning wheel; group contains c.1800 species; also known as wheel animalcules. (Phylum: Rotifera.)

The rotifers make up a phylum of microscopic, and near-microscopic pseudocoelomate animals. Leeuwenhoek is mistakenly given credit for being the first to describe rotifers but Harris had produced sketches in 1703.

Structure and form

Rotifers get their name (derived from Latin and meaning "wheel-bearer";

Rotifers have a variety of different shapes.

Like many other microscopic animals, adult rotifers frequently exhibit eutely - they have a fixed number of cells within a species, usually on the order of one thousand.

Reproduction

Rotifers belonging to the Class Seisonoidea reproduce sexually, those in the Class Bdelloidea reproduces asexually, and most rotifers in the Class Monogononta alternate sexual with a series of asexual generations.

Males in the Class Monogononta may be either present or absent depending on the species and environmental conditions.

Bdelloid rotifers are unable to produce resting eggs, but many can survive prolonged periods of adverse conditions after desiccation. Under drought conditions, bdelloid rotifers contract into an inert form and lose almost all body water;