Morphology of the mouthparts, gastric mill and digestive tract of the giant crab, Pseudocarcinus gigas (Milne Edwards) (Decapoda: Oziidae)

Abstract

Digestive tract histology, morphology of feeding appendages and gastric mill, and examination of gastric contents showed P. gigas to be carnivorous. The digestive tract showed typical decapod form and consisted of oesophagus, anterior and posterior gastric chambers, and midgut and hindgut segments. Dimorphic crushing-type chelipeds present food to the third maxillipeds. The mandibles and third maxillipeds tear the food; however, large fragments still reach the anterior gastric chamber. The mandibles are dimorphic, with the right mandible possessing a pointed beak-like structure. The ossicles of the gastric mill are blunt and used to grind and crush the ingested food. Dietary analysis showed predation on asteroid starfish and gastropod molluscs.