The Gut, Hepatopancreas and Digestion

Abstract

The isopodan alimentary canal consists of a straight tube and two pairs of digestive glands or hepatopancreas on each side. The subject received attention in early research (see McMurrich 1898; Schönichen 1899; Murlin 1902 for early literature). Later, studies by Schmitz and Schultz (1969), Alikhan (1968, 1969a, 1971) and Hassall and Jennings (1975) confirmed the general structure outlined. The digestive tract consists of a foregut, midgut and hindgut (Hassall 1977). A detailed account has been given by Hames and Hopkin (1989). The oesophagus contains acid polysaccharides (AB-positive at pH 2.5, see Lane 1988). The typhlosole runs along the dorsal part of the anterior gut (Hames and Hopkin 1989). This was not noticeable in Ligia (Nicholls 1931b). A peritrophic membrane (intima) lines the interior of the gut’s anterior side as well as its posterior end, but not its middle part (Lane 1980, 1988; Bettica et al. 1987; Brecko et al. 1991). In Cylisticus convexus there is no evidence for a midgut (Brecko et al. 1991). The gut undergoes moulting simultaneously with the whole animal (Palackal et al. 1984).