Mechanical functions of setae from the mouth apparatus of seven species of decapod crustaceans

The mouthpart setae of seven species of decapods were examined with macro-video recordings and scanning electron microscopy. The general mechanical (nonsensory) functions of the different mouthparts are described and an account of their setation is given. This offers the possibility to determine the mechanical functions of the different types of setae. Pappose setae do not participate in food handling but in general make setal barriers. Plumose setae likewise do not contact food objects but assist in current generation. Papposerrate setae are rare but they were seen to assist in pushing food particles into the mouth. Serrulate setae are very common and mainly participate in gentle food handling and grooming. Serrate setae are used for more rough food manipulation and grooming. The roughest shredding, tearing, and manipulation of prey items are handled by the cuspidate setae. Simple setae seem to be divided into two populations with very different functions. On the maxillipeds of Panulirus argus they are used for shredding, tearing, and holding the food objects, but on the basis of maxilla 2 of three other species they appear to have very little mechanical influence and only when handling small prey items. The functional scheme seems to be consistent within the Decapoda.