Dragonflies and damselflies perform a similar task, but in the larval stage. Aquatic sowbugs are also active. Many waterfleas display rounded heads in winter, when the water is cold, and pointed heads in summer, during periods of warmth. Horsehair worms have a unique solution to the problem of winter temperatures. They choose to either hibernate among shore plants or to remain in the host body and parasitize.
Snails become very inactive in winter.
Those present in water that freezes solid, burrow into mud and plant debris to hibernate. Some water mites may temporarily do this as well. Mussels do not grow during the winter, yet they are sometimes seen active through clear ice. Crayfish remain active, but not as active as they are in the summer. They tend to burrow into wet meadows and banks.