Adult water mites are piercer-predators feeding on insect larvae and small crustaceans. They use retractable piercing mouthparts (chelicerae) to inject digestive enzymes into the prey and suck out dissolved tissues. Juveniles are external parasites on insect hosts.
Water mites inhabit lakes, ponds, marshes, swamps and slow flowing parts of streams and rivers.
Most water mites are swimmers. They use legs equipped with rows of swimming hairs to propel themselves through the water. Some species prefer crawling among aquatic vegetation.
The size of most water mites ranges from 2 to 3 mm. Some species reach sizes up to 7 mm.
Water mites undergo metamorphosis of several stages that is somewhat similar to complete metamorphosis of insects.
When feeding, the prey is held by the pair of finger-like pedipalps, which may be mistaken for antennae (mites have no antennae). Water mites have two pairs of eyes often situated so close together, that there seems to be only one pair. Oval body is composed of large abdomen and cephalothorax. However, there is no obvious segmentation and the body appears undivided. Adults have four pairs of legs (immature stages have three pairs of legs). The purpose of bright coloration is to inform the predators about their bad taste.