Representatives of the Ciliates, or Ciliates, are the most highly organized protozoa.
Characteristic features of ciliates:
* on the surface of the body they have cilia (locomotion organs), which are in constant motion, which ensures the rapid movement of ciliates.
* There are two nuclei in the ciliate cell, different in size and function. The large (vegetative) nucleus – the macronucleus – is responsible for nutrition, respiration, movement, metabolism; small (generative) nucleus – micronucleus – participates in the sexual process.
In the same reservoirs where the amoeba Proteus and Euglena green live, this single-celled animal 0.5 mm long with a body shape resembling a shoe is also found – ciliate shoe.
Infusoria-shoes quickly swim with a blunt end forward, moving with the help of cilia.
On the body of the ciliate there is a depression – the cellular mouth, which passes into the cellular pharynx. Larger cilia are located near the mouth. They drive bacteria down the throat along with the stream of water – the main food of the shoe. At the bottom of the pharynx, a digestive vacuole forms, into which food enters. Digestive vacuoles move in the body of the ciliate by the current of the cytoplasm. In the digestive vacuole, food is digested, the digested products enter the cytoplasm and are used for the vital activity of the ciliates.
The undigested residues remaining in the digestive vacuole are thrown out through a special structure at the posterior end of the body – powder.
In the body of a ciliate-shoe, there are two contractile vacuoles, which are located at the front and rear ends of the body.
Each vacuole consists of a central reservoir and 5–7 channels directed to these reservoirs. The entire cycle of contraction of these vacuoles takes place once every 10–20 seconds: first, the channels are filled with liquid, then it enters the central reservoir, and then the liquid is expelled outside.
Like other free-living unicellular animals, ciliates breathe through the integument of the body.