The water scorpion has a flattened, broad body with two breathing tubes at the tip of the abdomen. This aquatic insect measures between 17 and 30 millimetres in length and is 6 to 10 millimetres wide. The water scorpion's head is small and triangular, with bulging eyes, sharp mouthparts and very short antennae. Its body colour ranges from dark grey to greyish brown. Its dark front legs resemble the claws of a scorpion and reach up to 12 to 20 millimetres in length. The water scorpion has a red upper abdomen with a black base and tip, and its wings have red or yellowish veins.
Water scorpions inhabit freshwater bodies in Europe, Africa and North Asia. When holding onto leaves or stems they are camouflaged from predators and prey by their colour and shape, which make them look like sticks or twigs.
Water scorpions are not good swimmers and prefer to walk on mud or between water plants. However, they are good flyers, particularly in autumn. They feed on insect larvae, young fish and tadpoles and catch their prey by hiding in a camouflaged trap. When prey of a suitable size passes by, they use their hind legs to launch themselves forward with lightning speed to seize their victim.