Perna perna (Linné, 1758) occurs on the Atlantic littoral from Venezuela to Uruguay. The main organ systems were studied in the living animais, particular attention being paid to the ciliary feeding and cleansing mechanisms in the mantle cavity. The anatomy, functioning of the stomach and the ciliary sorting mechanisms are described. The siphons belong to type A (Yongf. 1948b), the ctenidia to type B( 1) (Atkins 1936c) and the stomach is of type III (Purchon 1957) or Section I (Dinamani 1967) with sorting mecanisms of type A and B (Reid 1965). A general comparison was made between the genera of the Mytilidae known and some features of Mytella Soot-Ryen, 1955.
Bivalvia; Mytilidae; Perna perna; functional anatomy; Brazilian littoral