FUNCTIONAL-MORPHOLOGY OF THE FOREGUT OF THE SPIDER CRAB NOTOMITHRAX-URSUS (BRACHYURA, MAJIDAE)

The morphology of the foregut of the spider crab Notomithrax ursus is described from stereomicroscope and SEM examination. The foregut is di vided into 2 parts: a large, anterior, cardiac chamber and a smaller, posterior, pyloric chamber. The cardiac chamber is well supplied with muscles and is lined with chitin thickened in places to form a complex , articulating set of ossicles. Some of these ossicles are developed i nto teeth which grind up the food. Other ossicles and setae inside the cardiac chamber appear to direct the movement of food through the car diac chamber and sort the food according to particle size as digestion takes place. The pyloric chamber acts as a filter to separate digeste d liquid, which is directed to the hepatopancreas for absorption, from solid particles which are directed to the midgut far excretion. The m orphology of the foregut of N. ursus, in particular, ossicle structure , supraampullary folds, and degree of setation, suggests that it is ad apted to an unspecialized, macrophagous diet.