Mucus-net feeding on organic particles by the vermetid gastropod Dendropoma maximum in and below the surf zone

Dendropoma maximum is a sessile marine gastropod that inhabits reef flats along a distinct, shallow, sub-tidal zone and uses mucus nets for passive suspension feeding. We tested the hypothesis that surface waves improve food capture by animals inhabiting the surf zone, D. maximum feeds mainly on suspended detrital particles that are highly abundant in its habitat, Its feeding strategy depends on ambient currents, not only for the transport of suspended particles to the filtering apparatus but also for the spreading of the mucus net and for determining its shape and size. Using an in situ experiment, we observed a 1.7-fold decrease in prey capture rates among animals transplanted from the surf zone to 5 m depth, where most of the flow was unidirectional. Part of the reduction in feeding rate could be attributed to a lower concentration of detrital particles at the deeper habitat. However, laboratory experiments in a recirculating flume showed that the mucus net produced by the animals under oscillatory flow was larger than under unidirectional flow. D. maximum is well-adapted for trapping detrital particles under the unique hydrodynamic conditions in the surf zone.