Seawater entered the Y-maze through two small branches, which converged in the choice chamber. The flow speed in the two branches was ~1cm [s.sup.-1].
At the conclusion of part 1, the robustus male was again placed at the end of the choice chamber, where it was re-acclimated for 15 min.
Only one female remained for 30 min in the choice chamber. The female that chose the typus male entered and left the typus branch twice before finally staying with the typus.
The robustus males that selected the branch with the receptive female were not faster to react (mean [+ or -] SD: 4.33 [+ or -] 2.75 min) than the robustus males that selected the nonreceptive female (mean [+ or -] SD: 6.85 [+ or -] 5.63 min) (t-test: t = -0.805, [t.sub.0.05(2),6] = 2.447, P = 0.452); the other males reacted late or never left the choice chamber during the 30-min observation period.
These animals were tested in a choice chamber (see Fig.
In the present work, the header tank, stimulus tanks, and choice chamber itself were all made from clear acrylic plastic.
The choice chamber was positioned on a wet bench close to the sea urchin holding tank, so quick transfers of experimental animals were possible.
To run the experiments, the system was set with similar flow rates of clean seawater entering each side of the choice chamber, thus reducing any confounding effects of rheotaxis.
(3.) No response: part of the animal remained on the drainage base plate or the animal moved to the sides of the choice chamber such that at least part of its body was in line with the base plate.
After each experiment the choice chamber was thoroughly rinsed and cleaned of all animal debris.
The spider families tested in the Discrimination trials involving three chambers with varied levels of host cues differed significantly in the degree to which they settled in the choice arenas (minimally containing foliage) versus in the release location (network of tubes connecting the choice chambers) ([chi square] = 43.3, df = 5, P < 0.0001).
The Anyphaenidae was the only spider family that significantly settled in the tubes that interconnected the choice chambers to one another as opposed to actually settling in the foliage or nests of A.