The rate of feeding of the bryozoan,Zoobotryon verticillatum

Abstract

Summary The ctenostome bryozoan Zoobotryon verticillatum was found to clear suspensions of four species of algae, at rates ranging from 0.152–1.05 ml per zooid per hour, or 13.9–96.2 ml per mg dry weight per hour, when the algal suspensions were below the satiation concentrations and thus maximum clearance rates would be expected. Suspensions of Monochrysis lutheri, a small flagellate on which the bryozoan grew well and with which most experiments were made, was cleared below the satiation concentration of 7,900 cells per ml, at the mean rate of 0.368 ml per zooid per hour or 33.7 ml per mg dry weight per hour. Satiation concentrations of the four species of algae were of the same order as the highest concentrations of nannoplankton to be expected in the bryozoan's natural habitat. The bryozoan colony fed fairly constantly over a 48 hour period. Assuming oxygen consumption was similar to that of other bryozoans, Zoobotryon verticillatum cleared about 11.6 litres per ml of oxygen consumed.