Dataset: McKeon_et_al_2012 Multiple Defender Effects Symbiont Behavior

We used behavioral observation methods based on those of Glynn (1980) to measure the reaction of Pocillopora exosymbionts to Culcita presence at different vertical locations on the colony. A coral colony with both Alpheus and Trapezia exosymbionts was placed on an elevated pedestal within a large seawater aquarium. Culcita was presented to the coral sequentially in two different experimental positions, where Culcita was held against the side or the top of the coral colony, respectively. Each trial alternated starting position and lasted 3 min with a 5-min rest period between treatments. Defensive behaviors were scored within 3 min with actions recorded on a per minute basis for proximity and degree of contact of the exosymbionts with the Culcita. If the Trapezia were viewed by the observer to show any response to the presence of the Culcita (usually adjusting its position to directly below the Culcita while remaining deep within the branches of the coral), it was given a score of 0.25. If the Trapezia advanced further, to within 2 cm of the Culcita, then it was given a score of 0.5 points. One point was added each time the Trapezia attacked by snapping at the body or tube feet of the Culcita, and an additional two points were given if the Trapezia attack resulted in a cut to the Culcita or removal of tube feet. If the Trapezia retreated and then re-engaged, the scoring system was restarted and all bouts were summed. The defensive snap of Alpheus involves a distinctive snapping sound (Glynn 1980), each of which was given a score of 1 point.