Gammarus Pulex. Normally referred to as a shrimp but in fact Gammarus Pulex are freshwater amphipods. Anatomy of an amphipod



Amphipods are characterized by three traits; 1) the absence of a carapace, 2) the
first thoracic segment being fused to the head, and 3) the abdomen being divided into two
parts each with three segments. .
Reproduction is achieved through external fertilization, and mating behavior
varies. Typically, the male locates a preparturial female by using his antennas to detect
pheromones from the female. The male then rides, or carries, the female with her dorsum
facing his venter for several days. The female goes through a parturial molt, signaling her
ability to mate. Fertilization occurs in the marsupium where eggs are then brooded and
ventilated by the beating of the pleopods. Amphipods undergo direct development, and
average twenty molts in a typical one-year life cycle (Rupert et al 2004)