Further observations on the buoyancy of Spirula

Abstract

INTRODUCTIONIn earlier papers we have given an account of work on the three kinds of chambered shells which are found in living cephalopods, i.e. those of Sepia, Nautilus and Spirula, and shown that, although these animals differ markedly from one another in the structure of the shell and its position in the animal, there are nevertheless great similarities in the pattern of events leading to the formation of a new chamber and the way in which liquid is pumped out of it and gas diffuses into it (Denton & Gilpin-Brown, 1961 a, b, c; 1966; Denton, Gilpin-Brown & Howarth, 1961, 1967). We advanced the hypothesis that this pattern must have been the same for all the chambered shelled cephalopods, including the fossil nautiloids, ammonites and belemnites.