Transport Speed of the Mucous Feeding Filter in Clavelina lepadiformis (Aplousobranchiata,Tunicata)

The transport speed of latex spheres trapped in the mucous feeding filter of 30 specimens of Calvelina lepadiformis (Müller 1776) was measured by microscopical examination and a stop watch. The speed across the gill screen increased from 24 μm s^?1 in small animals to 220 μm s^?1 in large ones. The net translocation speed of the food roll behind the dorsal Lamina was generally much slower but revealed a similar trend (7–78 μm s^?1). The increased feeding filter speed in larger animals was parallelled by an increased branchial circumference in such a way that the duration of water filtration through each part of the filter remained almost constant (between 38 and 56 s as means for all groups of animals). The amount of filter secreted by large animals approached 150 cm² h^?1 or 2.5 m² week^?1. Based on available data on water filtration rates it could be calculated that the speed of water through the filter was of the same order of magnitude as the observed translocation speed of the filter.