Synchrony in the digestive diverticula of<i>Mytilus edulis</i>L.

Abstract

The organization, cellular composition and function of the digestive diverticula has been described for a large number of molluscs (Nakazima, 1956; Owen, 1966; Purchon, 1968). Changes in the digestive cells which are associated with intracellular digestion have also been widely recognized (Graham, 1938; Carriker, 1946; J. E. Morton, 1955, 1956, 1959; Owen, 1955, 1966, 1970, 1972; Sumner, 1965, 1966 a, b , 1969; Morse, 1968; McQuiston, 1969; Walker, 1970; Merdsey &amp; Farley, 1973). In general the digestive cells show three cyclic phases, (1) absorption, (2) digestion, (3) fragmentation and excretion, and these phases, with only minor modifications, are typical of most molluscs (Owen, 1966). In many groups, especially gastropods, the changes in the digestive cells within the tubules of the digestive diverticula often appear to be synchronized and consequently the tubules have a uniform appearance throughout the diverticula. In the Bivalvia, however, this type of synchrony has not generally been recognized. Since bivalves have been considered to feed more or less continuously (Purchon, 1971; Winter, 1973) it is not surprising that a homogenous appearance was only exceptionally observed, e.g. J. E. Morton (1956), J. E. Morton, Boney &amp; Corner (1957).