Heterospecific aggression and dispersion in two species of sea anemones in the Florida Keys

The relationship between heterospecific aggression and dispersion in sea anemones is poorly understood. This relationship was elucidated for Bartholomea annulata Leseur and Aiptasia pallida Verrill at a quarry in the Florida Keys. Laboratory experiments indicated that B. annulata was the aggressor. Individuals of both species moved to avoid contact under both laboratory and field conditions. Field assessment of dispersion revealed aggregated patterns, as well as vertical segregation between the species. Bartholomea annulata was most abundant at a depth of 0.75 m, while A. pallida dominated at the surface. Heterospecific aggression may be just one but probably an important one of several factors mediating the spatial distribution of these two sea anemones.