Locomotion on the Water Surface - Organisms

Because the surface of water is in tension, it can physically support an organism that has both a hydrophobic skin and a mass that is small relative to contact surface area. Many species of arthropods possess both of these properties and a few are quite adept at life on the water surface. Among these are water striders (Insecta, Gerridae) and fishing spiders (Arachnida, Pisauridae), both groups of arthropods that use the surface of fresh water during foraging, predator avoidance, and searching for mates.

Experimental data from our laboratory indicate that water striders and fishing spiders move across the water surface using the same drag-based propulsive system: dimples formed by the interaction of the legs and the water surface expand the effective frontal surface area of the propulsive legs so that, when the legs move backward, the animal is propelled forward more efficiently.

Both water striders and fishing spiders are widespread throughout the world. For information about their phylogenic relationships to other arthropods, consult the Tree of Life. Information about a variety of spiders and their kin can be found at the Arachnology Home Page. Similarly, the Entomology Index provides access to information on insects.