Biomes Dealing with Exposure to Sunlight Life on earth is dependent on the sun, yet the sun can be harmful to creatures on land.
Dehydration is a big problem for animals living in air.
People still die of dehydration today. Keeping enough water in the body requires a protective skin and also a new awareness of a sense of thirst. Shade plants can have their leaves sunburned, and delicate animals, like little frogs, seek refuge in the water when the sunlight gets too strong. The earliest land animals had to adapt to sunlight, and only the best-suited animals survived. An important development was water-proof skin.