The Nose Takes a Starring Role; July 2002; Scientific American Magazine; by Kenneth C. Catania; 6 Page(s)
The renowned physicist John Archibald Wheeler once suggested, "In any field, find the strangest thing and then explore it." Certainly it is hard to imagine an animal much stranger than the star-nosed mole, a creature you might picture emerging from a flying saucer to greet a delegation of curious earthlings. Its nose is ringed by 22 fleshy appendages that are usually a blur of motion as the mole explores its environment. Add large clawed forelimbs, and you've got an irresistible biological mystery. How did this creature evolve? What is the star? How does it function, and what is it used for? These are some of the questions that I set out to answer about this unusual mammal. It turns out that the star-nosed mole has more than an interesting face; it also has a remarkably specialized brain that may help answer long-standing questions about the organization and evolution of the mammalian nervous system.
It may comfort you to know that star-nosed moles (Condylura cristata) are small animals, tipping the scales at a mere 50 grams, about twice the weight of a mouse. They live in shallow tunnels in wetlands across much of the northeastern U.S. and eastern Canada and hunt both underground and underwater. Like the other roughly 30 members of the mole family (Talpidae), the star-nosed mole is part of the mammalian order Insectivora, a group known for its high metabolism and voracious appetite. So the tiny star-nosed mole with its big appetite must locate enough prey to survive cold northern winters. It finds earthworms in soil, as other moles do, but in addition it has access to a host of small invertebrates and insect larvae found in the rich mud and leaves of its wetland habitat and in the ponds and streams where it swims along the murky bottom to root out prey. And seeking prey is where the star comes into play. The star is not part of the olfactory system-which governs smell-nor is it an extra hand used to gather food. Instead the star is a touch organ of unsurpassed sensitivity.