Tundra habitat is found in the Arctic, beyond the permanent ice pack that surrounds the North Pole. It is a habitat of contrasting seasons, with temperatures as low as –76 degree Fahrenheit (–60 degrees Celsius) in the winter and almost no sunlight, to temperatures as high as 77 degrees Fahrenheit (25 degrees Celsius) in the short summer season.
Wetland habitats are complex and found all over the planet, from the polar regions to the tropics. They include marshes, swamps, bogs, and lagoons, and they are constantly changing, based on the seasons, water levels, tides, and migrations of birds and mammals. Wetlands may have areas of permanent standing water, although that may change with rainy and dry seasons, or they may be areas of damp, muddy, waterlogged soil.
Rivers are flowing water habitats, which can vary from an icy mountain stream to a huge tropical river. Lakes are still-water habitats, ranging from tiny rain pools to giant lakes many thousands of feet (meters) deep. Each of these habitats has its own types of plants and animals, depending on factors such as how fast the water moves and is replaced, the nature of the rocks and soil, and the chemical makeup of the water itself.