CONICET | Buscador de Institutos y Recursos Humanos

Sea anemones are important members of many marine ecosystems. For example, they establish symbiotic relationships with a variety of other organisms and they are often the dominant predators in marine communities. The role of sea anemones in trophic food webs is an interesting aspect of their ecology. Most trophic ecology studies have focused on the diet of temperate species, while little is known about tropical species. We studied the feeding habits of the intertidal sea anemone Anthopleura nigrescens, in order to understand the role of these organisms in tropical ecosystems by examining the gut contents of specimens collected during low tide at two locations on Costa Ricas Pacific coast. We also compared the prey items captured during diurnal high tides with those captured during nocturnal high tides, in order to determine differences in prey items. We found 19 different types of prey items in four main groups: mollusks, annelids, crustaceans, and other arthropods. Bivalves and ostracods are the main prey items, but A. nigrescens occasionally feeds on polychaetes, insects, and invertebrate eggs as well. We also found that copepods are commonly captured during nocturnal high tides, whereas they are rarely captured during diurnal high tides. Sea anemones have been described as polyphagous opportunistic predators that feed on organisms that blunder into their tentacles. The variety of prey items captured by A. nigrescens, including insects, illustrates this well; but its diet was not more diverse than that of temperate sea anemones. The feeding habits of A. nigrescens are similar to that of many temperate anemones that feed mainly on bivalves and crustaceans. However, this is the first study to show that nocturnal high tides bring different prey items such as copepods, which are an important component of this sea anemones diet.