Some animals lick dew off plants or eat leaves to get water. Desert beetles stand on their heads so that the water droplets from fog trickle down into their mouths.

All birds need water - even desert birds. The sand grouse of Africa finds water wherever it can and transports it to its young in its nest. How?

The male has special sponge-like feathers on its belly that it soaks in water. Back at the nest, the chicks drink the water from the male's feathers.

Animals

Osmosis and animal cells

If a solution is separated from pure water by a partially permeable membrance,the pressure which must be applied to prevent osmosisis called the osmotic pressure. As this situation is a hypothetical one, and as a solution does not actually exert any pressure in normal circumstances, the term osmotic potential is preferred. As the osmotic potential is the potential of a solution to full in water, its value is always negative. The more concentrated a solution, the more negative is its osmotic potential.

When two solution have the same osmotic potential they are said to be isotonic. Where one solution has a greater osmotic potential (i.e. the less concentrated one) than another it is said to be hypertonic to it. The one with the lower osmotic potential (i.e. the less concentrated one)is said to be hypotonic.

Water for the support of animals

Animals and plants that live in water rely on it for support. Animals such as jellyfish do not have a skeleton but rely on water to support their body organs. There are also large plants living in water. Large land-living plant such as trees has to produce wood to support their trunks. Some of the largest seaweeds are many hundreds of yards in length and they get all the support they need from the water. When they are washed up on to the shore they collapse as they have lost their means of support.

Many animals rely on water for internal support. Worm, such as the marine fireman, have a central cavity that contains water. The worm's muscles push on the fluid cannot compress, so it is forced toward one end of the worm. By controlling the pressure on the fluid and there it is applied, the muscles can cause the worm's body to change shape. By using one set of muscles, the front end of its body extents forwards, while another set cause the back part of its body to contract and move toward the front end. By repeating this process, the worm can move its whole body forward.

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