Loricate Rotifers.
A lorica is a hard or semi-hard shell which forms the outer surface of the body
of some rotifers. There is great variety in the shape of rotifer
loricae, and in some species they can be ornately sculptured, whilst
others have long spines and projections or blades. Semi-loricate is a term
used to describe less obvious body thickenings which (along with other features)
distinguish these rotifers from the bdelloids. The markings on the lorica are
frequently used in species identification.
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Brachionus is a common loricate rotifer in
fresh water ponds and streams. The complex corona creates a powerful
feeding current when the rotifer is attatched by the cement glands in its
two-toed foot, or propels it rapidly through the water when its grip is
released.
The single red eye is visible, and the yellow bodies are probably eggs, developing within the ovary.
Darkfield, 200X. |
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This Trichocerca rotifer shows a remarkable degree of asymmetry particularly in the very unequal length of its toes. The left toe is greatly extended, whilst the right is degenerate and can only be seen with difficulty winding
around the base of the elongated one. This pronounced asymmetry is also
seen in the jaws, which in this picture have just nipped a hole in the
algal filament at the cell-wall junction of two cells, and the rotifer is
seen in the act of draining both cells of their contents. Its stomach is
green from earlier similar meals.
Darkfield, 200X. |
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This largish rotifer has a dorsal crest running the length of the body.
It is possibly a Trichocerca, although the jaws don't look right for that.
Can anyone positively identify this beast?
Darkfield, 200X. |
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Unidentified loricate rotifer (possibly Macrochaetus sp.).
Darkfield, 300X. |
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Testudinella (from Latin: testudo, tortoise) acquired its name from its ability to draw both head and foot rapidly inside its flattened, almost circular lorica when disturbed.
Some species are planktonic, others are periphytic (found around plants). This one is feeding whilst attatched to a hanging rootlet of the common duckweed (Lemna minor).
Darkfield, 200X. |
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