PARTICLE CAPTURE IN THE MUSSEL MYTILUS-EDULIS - THE ROLE OF LATERO-FRONTAL CIRRI

Microscope video graphs of particle paths near one-filament-thick muss el gill preparations, stimulated with a nerve transmitter (10(-6) M se rotonin which restores normal ciliary activity), were used to disclose the capture of 6 mu m algal cells. Suspended algal cells carried with the water were stopped for a while at the entrance to the interfilame nt gap by the action of the latero-frontal cirri (Ifc), and transferre d to the frontal side of the filament to be transported towards the ma rginal food groove. The event of transfer took place during approximat ely a time interval of 1/50 to 1/25 s. To gain a better understanding of the capture mechanism and retention efficiency versus particle size , the flow through and around the Ifc was theoretically estimated. Nor mally beating Ifc create periodic, unsteady, three-dimensional flows a t the entrance to the interfilament canal. During the active beat most of the water is deflected to flow around the branching cilia of the I fc while some of the water is strained by these. Large particles (> 4 mu m) are stopped and transferred to the frontal current, whereas smal ler particles either follow the flow around the Ifc and escape or they are stopped by the branching cilia.