Sheri Amsel Freshwater Wetlands: Lakes & Ponds As the sun sets on a northern lake, many animals are just starting their day. A raccoon (1) begins to search along the shore for frogs (2) and crayfish. Nearby, a muskrat (3) roots in the cattails (4) for leaves to line its den. Dragonflies (5) buzz over the water snatching up mayflies (6) in flight, while a giant water bug (7) hunts under the water for small prey. An otter (8) hops onto the rocks after fishing. A painted turtle (9) warms itself in the last rays of the sun. Overhead an osprey (10) watches for fish from above, while a snapping turtle (11) hunts them from below. A beaver (12) carries sticks to its underwater stash as a merganser (13) leads her chicks to the safety of the shallows for the night. A loon (14) calls. A bullfrog (15) croaks. A water boatman (16) zigzags around. A great blue heron (17) grabs a struggling perch (18) in its beak. The sun dips behind the mountains ending another busy day on a northern lake. There are freshwater lakes and ponds all over the world. The largest is Lake Superior, one of the Great Lakes in North America. The second largest is Lake Victoria in Africa. Lake Baikal, in Russia, is the deepest. In the U.S. alone there are more than 100,000 big lakes, each covering more than 100 acres of land, and many, many smaller ones. Canada is thought to have more than 3,000,000 lakes, which is more than half the world’s freshwater lakes. Lakes and ponds are broken down into four zones, and each has its own important habitat. The shallow area along shore is called the littoral zone. It is warmed by the sun all the way to the bottom and is the richest zone in plant and animal life. The open water away from shore, where only the top layer is warmed by the sun, is called the limnetic zone. Here tiny green algae and single-celled plants called phytoplankton float on the surface. They are so small you cannot see them, but they are very important to the lake’s food web. They are the producers making energy from the sun using photosynthesis and are the vital base of the food chain. The profundal zone is a deeper, darker zone below the open water where sunlight does not reach. There is very little oxygen to breathe, yet some fish have adapted to survive, as it is safe from many predators. The benthic zone is the cold, dark bottom of the lake. The animals that survive here are those feeding on the debris that falls from above. They include dragonfly larvae (19), freshwater clams (20) and crayfish (21). These are the decomposers. They are an important part of the lake’s food web and act as the clean-up crew. LITTORAL ZONE LIMNETIC ZONE BENTHIC ZONE PROFUNDAL ZONE 4 1 2 3 5 8 17 6 11 14 7 10 12 15 13 18 19 9 16 20 21
Sheri Amsel 94-4020 The shallow area along shore is warmed by the sun all the way to the bottom and is the richest zone in plant and animal life. The open water away from shore, where only the top layer is warmed by the sun grows tiny green algae and single-celled plants called _______________________________, that float on the surface. They are so small you cannot see them, but they are very important to the lake’s food web. They are the producers making energy from the sun using _______________________________ and are the vital base of the food chain. Down at the bottom it is dark and cold with little oxygen to breathe. The animals that survive here are those feeding on the debris that falls from above. They include dragonfly larvae (19), freshwater clams (20) and crayfish (21). These are the _______________________________. They are an important part of the lake’s food web and act as the clean-up crew. 4 1 2 3 5 8 17 6 11 14 7 10 12 15 13 18 19 9 16 20 21 Freshwater Wetlands: Lakes & Ponds As the sun sets, a _________________________ (1) begins to search along the shore for frogs (2) and crayfish. Nearby, a _________________________ (3) roots in the cattails (4) for leaves to line its den. _________________________ (5) buzz over the water snatching up mayflies (6) in flight, while a giant water bug (7) hunts under the water for small prey. An _________________________ (8) hops onto the rocks after fishing. A painted _________________________ (9) warms itself in the last rays of the sun. Overhead an osprey (10) watches for fish from above, while a snapping turtle (11) hunts them from below. A _________________________ (12) carries sticks to its underwater stash as a merganser (13) leads her chicks to the safety of the shallows for the night. A _________________________ (14) calls. A bullfrog (15) croaks. A water boatman (16) zigzags around. A great blue _________________________ (17) grabs a struggling perch (18) in its beak. The sun dips behind the mountains ending another busy day on a northern lake. 10 LITTORAL ZONE LIMNETIC ZONE BENTHIC ZONE PROFUNDAL ZONE