Antifouling adaptations of caridean shrimps: Cleaning of the antennal flagellum and general body grooming

Abstract

Structural specializations of chelipeds used by caridean shrimp in two kinds of grooming activity are described. In general body grooming, the chelipeds, and in some species, the last walking legs, nip, pick or brush material from the exoskeleton. When the cleaning chelipeds are the second pair, the carpal segment is multisegmented, increasing distal flexibility which aids in grooming. Tufts of compound setae and setal “chela locks” are characteristic of cleaning chelae. In representatives from 13 of 15 caridean families surveyed, brushes of serrate setae surround the carpal-propodal joint of the first cheliped. This setal structure is used in the specific task of cleaning the chemotactile antennal flagellum. Cleaning brushes on the last walking legs of some species are involved in general body cleaning. Experiments on Heptacarpus pictus showed that when the cleaning chelipeds were ablated, body parts became fouled with epizoites and particulate debris in experimental shrimps, while control shrimps showed little fouling. Suggestions on the adaptive role of general body cleaning in these natant animals are discussed. A survey of cleaning characters in representatives from 15 caridean families suggest that such characters are rather constant within a family. A possible correlation between the taxonomic success of a family and the degree of development of general body cleaning is suggested.