Thursday, May 24, 2012
This huge diversity of living things has come about because each within its environment occupies a niche that is different from all of the others. The differences may often be slight but no two creatures or plants can make identical demands on their habitat. Recent work has shown that in a species rich environment the use of the Sun’s energy is more efficient than in a species poor habitat. Within an environment, species are largely interdependent. If a species should be lost rapidly, there is likely to be a knock on effect as other plants and animals feel the consequences. The pattern of life in the whole are is changed and probably impoverished.
Wednesday, May 16, 2012
Many mammals live in water, but most have to return to land to breed. Only the whales and sea cows are fully adapted for life in the water. Their front limbs form flippers and their tails form lobe like flukes. Hind limbs are absent, apart from some skeletal remains inside the body. The animals mate and give birth in water, and the only thing that indicates a terrestrial origin is that they still breathe air.