So far I have only found a few specimens of Pleurotrocha petromyzon. This rotifer is transparent and its internal structure is clearly visible. Characteristic is the eyespot with some some spherical crystals at the end of the central ganglion (s. fig. 4). They may have the function of a lens. The foot glands of Pleurotrocha petromyzon are elongated in shape. They produce a mucous secretion which is collected in a reservoir between the glands and the toes. It is easy to recognize (s. fig. 3).
Pleurotrocha petromyzon feeds on sessile ciliates but also on dead crustaceans. Therefore, there is a maximum in the population of Pleurotrocha petromyzon in late fall, when there are many dead crustaceans. During this time, giant forms are also formed, which are about twice as large as the normal form.
Fig. 1 a-c:Pleurotrocha petromyzon. L = 283 µm. Different focal planes of a slightly squashed specimen from left. Obj. 40 X.
Fig. 2 a-c:Pleurotrocha petromyzon. L = 200 µm. Different focal planes of a second, slightly squashed specimen from right. Obj. 60 X.
Fig. 3:Pleurotrocha petromyzon. L = 283 µm. The specimen as shown in fig. 1 a-c in detail. BL = bladder, CG = central ganglion, FG = foot glands, Int = intenstine, MR = mucus reservoir, ST = stomach, TO = toes, Vit = vitellarium. Obj. 60 X.
Fig. 4:Pleurotrocha petromyzon. The eyespot (ES) with some spherical crystals (CR). TR = trophi. Obj. 100 X.
Fig. 5 a-b:Pleurotrocha petromyzon. Two focal planes of the trophi. Obj. 100 X.