Ecology and behaviour of a free-swimming tube-dwelling rotifer Cephalodellaforficula

SUMMARY. 1. Cephalodella for ficula (Ploima, Rotifera) lives in tubes it constructs itself. These tubes are built of mueus in detritus-rich environments. The tubes are often closed at both ends, arc not used as sieves, and are not eaten directly.
2. The rotifer swims back and forth in its tube and apparently lives on bacteria which are shed from the inner walls of the tubes. Because of surface-to-volume considerations, this feeding strategy is probably only possible for animals smaller than roughly 1 mm. Under low food conditions, rotifers inside a tube have a distinctly higher fitness than rotifers removed from their tube.
3. Given high food conditions, rotifers removed from a tube immediately build another. Grazing on particles outside the tube appears to take place when a tube is being lengthened. Rotifers do not leave the tube for routine feeding, but under conditions of starvation or very low oxygen concentration they will leave the tube and swim about.