Current-induced flow through living sponges in nature.

Flow velocities through and immediately adjacent to the excurrent openings (oscula) were measured in eight species of marine sponges in their natural environments with a two-channel thermistor flowmeter. Flow through the oscula was positively correlated with both normal and artificially augmented ambient flow in both normally pumping and inactive animals. These results indicate that the passage of water through these sponges is, in part, induced by ambient currents.