The still water of a pool and the running water of a river each have their own special group of creatures. By no means, the same kinds inhabit each part of a pool or river.
In ponds, during spring, newts, frogs and toads take to the water to lay eggs. Frog and toad tadpoles browse on soft vegetation. Newt larvae feed on worms and water fleas. Newt and frog tadpoles may fall prey to big beetles that dive and hunt under water. The shallow waters at the pool edge are popular with many birds. Mallard ducks, coots, herons, kingfishers, sticklebacks are some of them. In deeper water, large fishes, tench and bream, rudd and roach, pike and perch hunt for smaller fishes and plants near the bottom.
Between its source and the sea, a river may hold five kinds of habitats. First comes the narrow head stream. Here lives the small flattened crawling creatures. Next is the troutbeck in which lives the small aquatic insect larvae and dippers, a type of bird. In the minnow reach lives the caddis fly, dragonfly, nymphs, freshwater shrimps and cray fishes. The river next enters lowland reach. Here, worms, insects, mollusks and crustaceans are found in abundance. When the river meets the sea, ducks, geese, wading birds and gulls are found.