Grooming behavior and morphology of the caridean shrimp Pandalus danae Stimpson (Decapoda: Natantia: Pandalidae)

Grooming or cleaning is a frequent behaviorial activity of the shrimp Pandalus danae. Setal brushes on thoracic limbs scrape and rub other appendages and general surfaces of the exoskeleton. Chelate limbs nip and pick at edges of crevices in the cephalothoracic region. Scanning electron microscopy reveals that the setae composing the grooming brushes are equipped with characteristic tooth- and scale-like setules which serve as the actual rasping devices. Antennules, antennae and pereopods are frequently preened by the third maxillipeds and first pereopods, while large areas of the exoskeleton are cleaned by the third pair of walking legs and the chelate limbs. Shrimp with the general cleaning limbs ablated develop significantly greater infestations of the epizoic suctorian Ephelota than animals allowed to groom. Olfactory hairs on the antennules of shrimp deprived of the third maxillipeds become fouled with diatoms and debris while those on controls do not. Grooming behavior clearly prevents a build-up of settling organisms between molts and repeated cleaning of sensory sites is essential in maintaining contact with the environment.