ABSTRACT
Swarming by Dioithona oculata may enhance mating behavior by aggregating conspecific adults. Although light is the primary cue for initiating and maintaining swarms, chemical cues such as sex pheromones may help maintain individuals in a swarm. A behavioral repertoire for mating was determined in the laboratory. Males briefly contacted other animals to identify potential mates. Males displayed more mating behaviors with and only placed spermatophores on virgin females. Dense laboratory swarms (5.5 to 10.1 cm−2) formed in groups composed of only adult females, adult males, or copepodid stages 4 and 5, but not in a group of younger copepodid stages 3 and 4. Mating only occurred in laboratory swarms composed of males and virgin females. Pairs displayed distinctive behavior of sinking during mating followed by bursts of rapid swimming. These mating pairs may be more vulnerable to predation because of their swimming pattern. However, bursts of speed by coupled pairs approaches speeds of individuals escaping fish predators.
