Protothaca (Leukoma) pectorina (Lamarck, 1818) lives from the West Indies to Santa Catarina State, Brazil, in soft muddy beaches in quiet waters of protected bays with little amounts of suspended material. A study of the functional anatomy of P. pectorina and its ecological aspects were undertaken. The anatomy and functioning of the stomach and the mechanisms for selection of particles were observed. The siphons, ctenidia, labial palps and stomach were analised and related to the animal's natural environment. The siphons belong to type B (Yonge 1948), the ctenidia to type C (1a) (Atkins 1937). The ctenidia are homorhabdic (Ridewood 1903) and the stomach belongs to type V (Purchon 1960).
Bivalvia; Veneridae; Protothaca pectorina; functional anatomy; Brazilian littoral