Aspects of the biology of a gutless species of Solemya (Bivalvia: Protobranchia)

Abstract

A new species of Solemya is found to lack a gut. It has no provision for the collection of food particles. The ciliation of the mantle cavity functions only to cleanse and irrigate the mantle cavity. Assay of glandular tissues and histochemistry reveal no digestive enzymological apparatus. It is inferred that this species obtains nutriment in the form of dissolved organic molecules. The ctenidia provide a large surface area for such a function, and the lamellae are well supplied with blood. This benthic species, which is most common in the vicinity of pulp mills, lives in a U-shaped burrow in soft mud. The burrow is lined with mucus which is secreted by the large pedal gland. The organism is capable of sustained swimming by repeated adduction of the valves, which causes jets of water to issue from the posterior exhalant opening.