Lakes are stagnant waters that look quite peaceful to us. But the quiet is deceptive: above and below the water surface, life is anything but peaceful. Phytoplankton and zooplankton are eaten by small predators such as polyps or hydrachnidiae. Toebiters, dragonfly and beetle larvae are food for the water scorpion. As every animal feeds on different prey and in turn is eaten by various predators, a food web is created. The amount and variety of the lake inhabitants depends on the concentration of nutrients. In clear lakes, aquatic plants may spread down to a depth of 10 metres. Different zones with particular plant species are clearly visible. Also animals above the water profit from the rich underwater life, for example the waterfowl. Ever since the lake was formed, wind and waves have been carrying dead plants and animals to the shore, where they have sunk down and decomposed. At the same speed at which the lakeside grows, the water surface of the lake shrinks. With its extensive additional material the didactic DVD is ideally suited for use in the classroom.
