Muscular anatomy and aspects of the structure of the antennae of Anthosoma crassum (Dichelesthiidae: Siphonostomatoidae: Copepoda).

The muscular anatomy and fine structure of the antennae of adult Anthosoma crassum are described from specimens collected from jaws of shortfin makos. Casual observations of live parasites showed that embedded adult A. crassum can move toward or away from the host by shortening or lengthening the antennae, respectively. These movements were controlled by antennal retractor muscles. Microprotuberances located on the distal antennal segments may increase friction between these copepods and their hosts, thus strengthening parasite attachment.