Fish, which cannot regulate their own body temperature, move to a part of the lake where the water temperature is optimized for digestion and metabolism. Other fish maintain warmer temperatures in parts of their bodies through the use of heat-exchanging vessels. In these manners, fish have adapted to survival in the cold waters under the ice. Beavers, otters, and muskrats also make changes for the winter. Resident of channels, ponds, and streams, beavers spend the winter in their sturdy and well-stocked lodges.
Beavers usually store enough food to stay put during the chilly months of winter.
Otters maintain a hole in frozen lakes through which they can do their fishing. This appears fun for the otters, but is also a useful adaptation allowing them to travel over deep snow in search of food. Muskrats live in their lodges during the winter, but come out to forage for food. Their winter diet consists mainly of rootstocks of water plants like cattails, arrowhead, or pondweed. Other lake and pond animals leave during winter months.