Meeting Abstract

P3.94  Friday, Jan. 6  The anus as a second mouth: Anal suspension-feeding by an oral deposit-feeding sea cucumber JAECKLE, William B*; STRATHMANN, Richard R; Illinois Wesleyan University, Bloomington; Friday Harbor Labs and Univ. Washington, Seattle

Respiratory trees of holothurians are blind-ended evaginations of the posterior digestive system that are rhythmically inflated with seawater via the anus and are considered to have respiratory and excretory functions. We tested the assimilatory capability of the respiratory tree epithelium by exposing adults of the oral deposit-feeding aspidochirotid sea cucumber Parastichopus californicus to (1) 14C-labelled unicellular algae and (2) iron-containing macromolecules and then following the distribution of the labels in tissues. The 14C label distribution indicated uptake by the respiratory tree and transfer to the associated hemal system. The iron-label from the protein ferritin and the polysaccharide iron dextran entered cells of the endothelium of the respiratory tree; mesenchyme cells within the connective tissue compartment of the respiratory tree were also labeled in ferritin exposed specimens, suggesting an avenue for transfer of materials. Nutritionally, holothurians appear to be bipolar anal retentives; the anus serves as a second mouth.