All birds have tiny arthropods called feather mites that live in their feathers. These mites are in a symbiotic relationship with the bird. That means they benefit the bird and the bird benefits them. Feather mites eat oil and fungi, thus cleaning the bird’s feathers and helping the bird to stay healthy. In return the mites get both a place to live and a regular supply of food.
The complication in this arrangement is that once a year, the birds molt, shedding their feathers so that new ones can grow. If the mites were to stay on a feather being molted, they would loose their home and die. Spanish biologists studying this phenomenon discovered that feathers about to be shed were free of mites. Before the feathers are shed, the mites get off and concentrate themselves on nearby feathers. The question is, “How do the mites know when the feather they are living on is about to be shed?
In a study of 63 songbirds in 13 species, all of them showed this capacity. The mites were able to pick up vibrations generated when the feathers to be shed began loosening in the bird’s skin. This is another case where trial-and-error does not seem possible. An error would be fatal when the feather is shed and the mite doesn’t get another chance to try again.
The Designer of all living things planned down to the shedding of feathers and made a way for mites dependent on feathers to survive. This behavior cannot be a product of the mite’s reasoning. It shows design. More than that, this and all symbiotic relationships in which two or more organisms depend on each other for their existence show design, not chance.
Natural History, February 2002, page 18
“arthropod,” “mite,” Wikipedia
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