Distribution of the Digestive Enzymes in the Gut ofArenicola Marina

Abstract

Investigations on the digestive enzymes of polychaetes have, in most cases, been limited to the presence or absence of protein (gelatin) digesting and starch digesting enzymes. These enzymes have been shown to be present in all the polychaetes that have been studied (Mansour-Bek, 1954; Dales, 1955; Marsden, 1963). The results for the lugworm, Arenicola marina (L.) have been varied. Recent work has indicated the presence of enzymes capable of digesting starch and gelatin in the oesophagus, oesophageal pouches and the stomach of the lugworm (Kermack, 1955). However, Brasil (1903) found that no digestion took place when secreted fluids of the oesophageal pouches were incubated with starch, though fibrin was digested both by these fluids and a water extract of the ‘caeca’. Nicol (1930) records the work of Krukenberg, who found that proteolytic enzymes were present in the gut of A. marina. Kermack (1955) noted that the stomach was slightly acidic, though Nicol (1930) records the work of Wirèn, who found that the contents of the ‘intestine’ and the ‘intestinal caeca’ of A. marina were alkaline. As there have been no detailed analyses of the digestive enzymes of the lugworm, a survey of the distribution of carbohydrases, proteases and lipases in the gut of A. marina was carried out, and the optimal range of the carbohydrases investigated.