Shrimp Hygiene: Antifouling Adaptations

Abstract

In both marine and freshwater environments, clean hard surfaces, e.g., exoskeletons of shrimps and other crustaceans, can be used by microbial and macroscopic fouling organisms as substrates to settle and grow upon. Sediment, detrital, and other suspended particulate matter can foul and clog sensory appendages and respiratory structures. Although periodic molting completely frees the shrimp body of fouling, experiments show that it often does not occur frequently enough to prevent deleterious fouling. Consequently, shrimps have evolved an array of morphological characters and behaviors for kee** the body, appendages, and gills free of fouling that can interfere with their various functions. The distribution of cleaning mechanisms among shrimp taxa is presented. Shrimps frequently clean their antennules with ras** and combing setae on third maxillipeds while the antennae also are groomed by specialized carpal-propodal setal brushes of the first pereopods. Various adaptations maintain the gills relatively free of fouling by particulate matter and microbial growth introduced from the respiratory flow. These include passive mechanisms, i.e., the “shrimp cough,” setiferous epipods and epipod-setobranch complexes. Active, directed cleaning of gills may be done by the first or second pereopod grooming chelipeds, which are equipped with setal brushes of multidenticulate setae. Fouling of the general body surfaces may impede both swimming and ambulatory function. Such fouling is reduced or prevented by bouts of cleaning by the grooming chelipeds and/or setal brushes on posterior pereopods. In carideans and stenopodideans, females groom incubated embryos to keep them free of sediment, microbial fouling, and embryo predators.