Meeting Abstract
The clonal anemone A. elegantissima has facultative mutualisms with two photosynthetic symbionts. Anemones predominantly hosting the unicellular green alga Elliptochloris marina are more light sensitive and are found in lower intertidal or shaded regions compared to brown anemones inhabited by the dinoflagellate Symbiodinium. A. elegantissima attach debris to their body, presumably protecting their tissues from excess light exposure. Little is known about how anemones perform this decorating behavior, nor its relationship to symbiont type. Using time-lapse video we established that particles are attached in a matter of seconds when verrucae make contact with them through expansion and contractions of the body wall. Tentacles are usually not used to position particles. Attachment strength of pebbles initially increases with time (1.1-7.3g at 6h, 1.5-24.8g after 48h). We hypothesized that anemones with light sensitive E. marina decorate more when exposed to light than those with Symbiodinium. To test this, anemones in both light and dark treatments were allowed to attach pebbles for 24h. Green and white (asymbiotic) anemones increased decorating in the light compared to the dark, consistent with the idea that this behavior protects them from sunlight. Brown anemones attached the largest number of pebbles over all, and did not differ between treatments. When allowed to travel freely along a light-dark gradient, white and green anemones preferred shaded areas, while brown anemones had no preference. Pebble cover on white anemones increased their preference for light areas of the tank. These findings suggest a differential control of decorating behavior based on symbiont type, and further verifies that this behavior is related to light exposure.
