Stability of the volume of air trapped on the abdomen of the water spider Argyroneta aquatica

Abstract

The water spider Argyroneta aquatica lives under water, diving to various depths from time to time. At rest, it breathes air trapped within its diving bell with a hydrophilic surface. Outside their diving bell water spiders trap air on their abdomen under a layer of hydrophobic hair. Is the structure of the layer of hair trapping a volume of air on the abdomen of the water spider Argyroneta aquatica under water related to its observed diving depth (of the order of decimetre)? A positive answer to this question is given, based on the law of Laplace in combination with information obtained from SEM- photographs of the abdomen of a water spider. © 2013 Neumann and Woermann.