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BIOLOGY

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Habitats: Notonectids are common aquatic predators. They are unusual in that they swim upside down. Food: Predaceous on other insects, aquatic amphibians including frogs and tadpoles, crustaceans and small fish. Feeding: Hair-like structures on Backswimmer legs detect water movements caused by prey. Forelegs grasp prey and the rostrum (beak) is inserted. Enzymes are injected that kill prey and liquefy internal structures which are consumed. Air gill: 3 longitudinal rows of hair-like structures on ventral surface of the abdomen trap air (mostly nitrogen) at the water surface. As oxygen in the bubble is used, more oxygen from the water diffuses into the bubble. When the nitrogen bubble is depleted the insect resurfaces to acquire more. Flight: Backswimmers adults fly well and may disperse to new aquatic areas (including swimming pools) in swarms at night.

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