Published online by Cambridge University Press: 11 May 2009
The tropical surf barnacle Tetradita squamosa (Bruguière) (Crustacea: Cirripedia) has a pair of lobulate digestive glands each connected to the dorsal surface of the foregut by a single duct. These glands have a central lumen surrounded by columnar epithelial cells and are the primary site of enzyme synthesis and secretion within the alimentary tract. A number of carbohydrases and proteases were detected, all of which exhibited optimal activity at an acidic pH. Gland cells discharge secretory products into the foregut ventriculus via apocrine secretion and this process is continuous; it is not correlated with tidal and subsequent feeding cycles. Possible reasons for the absence of feeding and secretory co-ordination are discussed.