Green tree ants swarm over oak blue caterpillars but they are not attacking them. They are drinking a sweet liquid that the caterpillars give off especially to attract the ants. The ants act like living armor, shielding the caterpillar from wasps that might lay eggs on it. The ants and the caterpillars are partners in nature.
She's gotta have it
She's gotta have it Evolutionary biologists are exploring the question
of why females of many species are attracted to the most colourful
males, and if these bright colours signal a male's quality.
Biologists think that the answer lies in the energy needed to grow
a colourful coat or plumage. It is suggested that only the
healthiest males with the best genes have the energy to display and
maintain the brightest colours, thus displaying their worth to
possible mates. Pigments called "carotenoids" help birds to achieve
bright plumage. Many of these pigments are gained by eating insects
which contain them. Biologists argue that only the fittest birds
would be able to find and eat enough of these insects to gain the
brightest plumage. Carotenoids found in the insects are also
important for immune defence and detoxification, so the brightest
males could indeed be signalling their evolutionary
worth. JANUARY 29, 2000, P. 22-26
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