Backswimming

Backswimming is the act of moving through water while oriented on the back, with the ventral side facing upward. This posture is characteristic of certain aquatic animals and is distinct from the more common front-facing swimming that most species use. In insects and some other aquatic organisms, backswimming describes a deliberate, inverted mode of locomotion that aids in prey capture, predator avoidance, or respiration.

Among the best-known backswimmers are insects in the family Notonectidae, commonly called backswimmers. They are aquatic hemipterans found in freshwater habitats such as ponds, lakes, and slow-moving streams. Backswimmers are usually small, dorsoventrally flattened, and dark-colored, with hind legs adapted for rowing and propulsion. They typically swim on their backs, using their oar-like hind legs and a flick of the abdomen to move through the water. To breathe underwater for extended periods, they trap a small air bubble beneath their body, which provides a temporary reservoir for gas exchange.

Backswimmers are largely carnivorous, preying on small invertebrates, tadpoles, and occasionally small fish. They use their piercing mouthparts to inject enzymes and suck out bodily fluids from their prey. They are generally nocturnal and can deliver a painful bite to humans if handled, though they are not aggressive toward people.

Ecologically, backswimmers play a role as both predators and prey within freshwater ecosystems. Their presence can indicate certain water-quality conditions, and they contribute to the diversity of aquatic insect communities.