Prey Capture in Lyonsiella Formosa (Bivalvia: Anomalodesmata: Verticordiacea)

Abstract

A specimen of the bathyal verticordiid Lyonsiella formosa has been obtained from Hawaii at 460m depth. Assignment of this specimen to L. formosa suggests that this species has a much wider range than hitherto believed. Dissection and subsequent histological examination of the specimen suggests a mechanism of prey capture completely different from that previously described for this species and resembling that attributed to Poromya granulata. Sensory papillae on the siphonal tentacles probably detect the prey. Prey capture is by eversion of an enormous hoodlike cowl of the inhalant siphon. Inversion brings the prey into the mantle cavity. Further distension of the siphon within the mantle cavity is believed to push the prey into the buccal apparatus comprising medially fused labia l palps . The unfused tips of the palps or the foot may assist in this. A model of the hydraulic changes that may occur in Lyonsiellaformosa to effect prey capture is described. The similar modes of feeding exhibited by L.formosa (Verticordiidae) and Poromya granulata (Poromyidae) suggest a close affinity.