|any of various long-legged aquatic insects of the heteropterous family Nepidae, which breathe by means of a long spinelike tube that projects from the rear of the body and penetrates the surface of the water|
any of the approximately 150 species of aquatic invertebrates of the family Nepidae (order Hemiptera). The water scorpion resembles a land scorpion in certain ways: it has scythelike front legs adapted for seizing prey and a long, thin, whiplike structure at its posterior end. This "tail," made up of two attached respiratory tubes, is extended above the surface of the water, enabling the animal to take in air. The bite of the water scorpion is painful but is far less harmful to humans than the sting of the true scorpion.
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