STRUCTURE OF FEEDING PALPS AND FEEDING-BEHAVIOR OF THE SPIONID POLYCHAETE POLYDORA-POLYBRANCHIA

The feeding palps of Polydora polybranchia have well developed ciliary food grooves. Along the grooves are numerous mucus glands and ciliate d papillae (sensory organs). The distribution and abundance of both mu cus glands and ciliary papillae on the feeding palps vary. In general, the largest papillae are located on the distal part of the palp where there are a few mucus glands; in the mid region there are sensory pap illae of different sizes and abundant mucus glands; and in the basal r egion there are neither papillae nor mucus glands. Laboratory observat ions indicated that feeding behavior and feeding modes were influenced by speed of water current and particle sizes. Particle selection take s place at the tip and mid regions of the palp where initial contact w ith the particles is made. A chemical mechanism for food particle sele ction is hypothesized. We hypothesize that the site of particle select ion on the palps is related to the presence of dense sensory papillae.