(i) Size: Organisms vary greatly in size ranging from microscopic bacteria to elephants, whales and large trees.
(ii) Colour: The colour of various plants and animals are quite different. Some worms are even colourless or transparent.
(iii) Life span: Life span of different organisms also varies greatly, e.g., a mosquito lives only for a few days while a turtle can live for around 200 years. Some pine trees also live for thousands of years. Vinila Choudary, Feb 9, 2012