The benthic disc-shaped foraminiferan Discobotellina biperforata (Collins, 1958) occurs in different morphologies: with or without lunules (holes) through the arenaceous test. Water flume experiments on preserved specimens from Moreton Bay in Queensland, Australia, as well as models, indicate that the lunules have a significant hydrodynamic function. They increase the ability of specimens to resist dislodgment and transport by flow. Experimental closure of the lunules resulted in specimens being swept away at lower current velocities. The various morphologies of D. biperforata have been suggested by earlier students to result from an alternation of generations. Different generations in foraminiferans are normally detected by studying the nuclei. A histological study on sectioned lunulate and non-Iunulate specimens shows that there is no difference between them in nuclear status. This result strongly suggests that they belong to the same generation.
Marine Ecology - Progress Series, 1996, Vol 140, p. 179-186