Symposium: Insect Behavioral Ecology--85: "Firefleas" of the Sea: Luminescent Signaling in Marine Ostracode Crustaceans

Abstract

Caribbean ostracodes of the genus Vargula secrete luminescent emissions either as bright, long-lasting clouds or as complex trains of shorter, precisely spaced pulses. The large, bright clouds are generally produced during late twilight and have an effective antipredatory function. These emissions are similar among all species. Conversely, complex trains usually occur for a limited time just post-twilight in specific habitats within reef and seagrass systems. These trains are species specific displays produced by males and are presumably directed toward sexually receptive benthic [= bottom dwelling] females. In most species, luminescing males are accompanied by silent satellite males. These swarms have characteristics of both leks and sprees. There are three primary display patterns among the approximately 15 species observed: 1) about two thirds of the species produce trains that progressively shorten, 2) about one quarter produce evenly spaced trains, and 3) one species produces pulsed displays from multiple males. In most species, displaying males will usually synchronize their signals, by entrainment, with distantly signaling males. This synchronization produces a spectacular, reef-wide, sweeping luminescence that is reminiscent of a slow motion version of the flashing of synchronous fireflies from Southeast Asia. The reproductive patterns, life history, and biological activities of these ostracodes, along with their unusual signaling patterns, suggest that there is strong male-male competition and probably female choice involved in their mating systems. They show interesting parallels and differences to various insect mating aggregations including fireflies, chorusing insects and insect swarms.