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Lorica

In some protozoa and many rotifers, a tubular, conical, or vase-shaped structure that acts almost like a shell makes up the lorica. In some microscopic organisms, the lorica is thin and flexible, like the chitin on an insect; on others, it's hard and thick, more like a shellfish.

The lorica fits loosely, and is closed at one end, with an opening at the other through which the soft parts of the organism can be extended; sometimes a flagella extends through here. The shell-like structure of the lorica may be made up of organic materials similar to that which makes up microtubules, or it may be made of calcium carbonate or even silica plates. Often, grains of sand and other naturally-occurring hard particles are incorporated into the lorica for strength.

All functions of life are conducted through the open end of the lorica, from eating to secretions, and because the organism must be free to move in and out, the lorica fits loosely. The lorica takes a number of different shapes and formulations and is fairly important in determining taxonomy of protozoans which bear the lorica shell. Similar to the lorica is the test, which some foraminiferans and rotifers possess.

Web Resources On Lorica

Cothurnia
Chitinous fibrils in the lorica of the flagellate chrysophyte Poteriochromonas stipitata

Book Resources On Lorica

Studies on the marine ciliate Favella by Arthur Shackleton Campbell
Protozoa and Other Protists by Michael A. Sleigh

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