Brachionus angularis is a very common rotifer that I find with plankton in many of my sampling locations. The species has an almost oval lorica that, however, appears somewhat angular. In contrast to many other planktonic rotifers with a lorica, this species has no spines, with the exception of two small spines on the anterior margin on the dorsal side (s. fig. 3 b). The anterior margin on the ventral side is slightly wavy, without spines (s. fig. 4 a). The ventral side of the lorica is usually granulated. The dorsal side, on the other hand, is often faceted, though not always (s. fig. 3 a). In general, this species is very variable.

The foot is long and ringed (s. fig. 1 c). The toes have distinct, thin claws (hard to see). When swimming, the foot usually remains retracted. It is only extended for a short time under slight coverslip pressure.

More images and information on Brachionus angularis: Michael Plewka-Freshwater life-Brachionus angularis