Four cases of an interaction between a pair of olms co-occurring in the surface pool. Individual olm’s numbers match those in Fig. 3. The plotted distance is the distance between both olms’ heads and expressed in body lengths [bl] of the larger olm in the pair. One body length distance is indicated with a dashed line. Time 0 represents the start of co-occurrence, i.e., the moment when the second olm of the pair emerged to the surface pool while the first was already present.