Position of larval tapeworms, Polypocephalus sp., in the ganglia of shrimp, Litopenaeus setiferus.

Parasites that invade the nervous system of their hosts have perhaps the best potential to manipulate their host's behavior, but how they manipulate the host, if they do at all, could depend on their position within the host's nervous system. We hypothesize that parasites that live in the nervous system of their host will be randomly distributed if they exert their influence through non-specific effects (i.e.

Polypocephalus sp. infects the nervous system and increases activity of commercially harvested white shrimp (Litopenaeus setiferus).

Larval tapeworms (Polypocephalus sp.) reside within the central nervous system of decapod crustaceans. Living within the nervous system would seem to create an excellent opportunity for the parasites to manipulate the behavior of their hosts, so we tested the hypothesis that behavior of white shrimp ( Litopenaeus setiferus ) would be correlated with the level of parasitic infection.