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Protozoa: Ciliates
The Colonial Ciliates. 
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Protozoa: Home Ciliates: Home Holotrich Heterotrich Peritrich Colonial Suctoria

  Colonial Ciliates.

Not a recognized taxonomic grouping, but one which suggests itself to those investigating life in fresh water, and is included here to assist in the visual identification of specimens. In both of the examples shown, the organisms of the colony are peritrich ciliates -- see the section on Peritrich Ciliates for a fuller description of these.


The individual cells of the Carchesium colony are very similar to individual Vorticellae, and their contractile stalks are joined at the top of a trunk section, also contractile. The contractions of the individuals are independent of the contraction of the trunk.

Click for a diagram of Carchesium.

Carchesium. A Carchesium colony attatched to a piece of decaying plant material. The picture is confused somewhat by the presence of another colony beneath, mostly out of the picture. Colonies of this size are quite common, and the combined effect of hundreds organisms constantly consuming suspended bacteria makes these and similar ciliates a powerful force in the purification of organically polluted waters.
Rheinberg: x25.
Carchesium expanded. A small Carchesium colony fully extended, attatched to a frond of the water plant Myriophyllum to which a few Vorticellae are also attatched.
Click the enlarged picture once to see the colony contracted (the picture below), then use the back and forward buttons on your browser to see the contraction again.
Darkfield: x100.
Carchesium contracted. Same colony as in the picture above with all organisms contracted in response to a disturbance. Click on the enlarged version of the picture above to see the transition between expanded and contracted states.
Movie film of a Carchesium colony often shows the colony fully expanded in one frame, and fully contracted in the next, showing that the contraction has taken place in a twenty-fifth of a second or less.
Resuming the expanded state can take 5 - 10 seconds.
Darkfield: x100.


Ophrydium colonies are usually encountered as gelatinous green blobs a centimetre or two in breadth, either free in the water or attatched to submerged plant stems or the undersides of floating leaves. The individual organisms, which resemble elongated Vorticellae, inhabit the surface of the clear jelly mass, and the green colour of the colony is due to numerous zoochlorellae within each individual. They are each attatched by a thread joined to a branched structure, and adjacent colonies may merge to form a continuous layer.

Ophrydium. A group of individuals from an Ophrydium colony. Each individual is densely populated with zoochlorellae which, as a result of their photosynthetic activity, provide the host organism with nutrients and oxygen. When disturbed, contraction of the elongated cell body pulls the individuals below the surface of the colony (see diagram).
Some workers have reported colonies of twelve centimetres in diameter, probably formed from the merging of numerous originally separate colonies.
Darkfield: x200.

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