Figure 1.

Schlieren observation of swimming helmeted D. lumholtzi. The animal entered the observation volume from the lower right and with four hops reached the position in the mid of the picture. It pumped a volume of water through the carapace to feed and, since there was little food, it hopped twice to the new position at the upper left. There it tried to feed again. Duration for this path was approximately 6 s. Scale bar, 0.1 cm.