Adaptive Modification of Appendages for Grooming (Cleaning, Antifouling) and Reproduction in the Crustacea

Appendages used primarily for feeding and locomotion have become secondarily modified for grooming and reproductive purposes in many crustaceans. Crustaceans use specialized brushes and combs composed of setae with a complex microstructure for scraping surfaces clean. Decapod crustaceans have the best-described cleaning behavior, with gill cleaning by a variety of mechanisms necessitated by enclosure of gills in a branchial chamber. Other crustaceans, particularly stomatopods, some peracarids, and ostracods, groom frequently. Some crustaceans avoid algal fouling by frequent molting, burrowing in abrasive sediments, or nocturnal behavior. In many species, appendages have also experienced specializations for reproductive purposes. The immobile sperm of crustaceans must be actively transferred by the male in crustaceans, and a variety of appendages have become modified for this task. The actual mechanics of reproductive appendages in crustaceans are still poorly known and remain a fertile topic for study.