How butterflies drink described in ScienceNOW: ScienceShots.

Butterflies feed using a long proboscis that looks like a straw to draw up many different fluids including water, nectar and juices in rotting fruit. However, fluid dynamics researchers have found that it actually works by capillary action, like a paper towel, rather than the pumping or sucking movement that propels liquids through a straw. This enables the butterfly to gently draw up many kinds of liquids of different densities. If it tried to use a pumping action on heavy liquids like fruit juices the extra pressure needed would cause the proboscis to burst.

Editorial Comment: How butterflies and moths evolved a feeding tube out of insect jaws is a mystery for evolution. The usual story is that insects changed their jaws into feeding tubes when flowering plants were evolving and nectar and fruit juices became available to drink. For this to be true, evolutionists would have to explain how changes in plants’ genes that produced flowers also changed insect genes for mouthparts and the brain circuits that recognise flowers provide liquid food, and make them go for a drink. Furthermore, the changes had to get the proboscis right, i.e. the capillary action, in the first generation, otherwise butterflies would have lost the struggle to survive and become extinct.

Evidence News, 26 May 2010

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