Star-nosed Mole // Condylura cristata
The star-nosed mole may lack ears and be functionally blind, but suffers no lack of sensory finesse as it prowls through its subterranean domain. Moles often have highly sensitive noses used to catch prey in the darkness, but even among moles this particular species’ nose is exceptionally high-powered. All moles’ noses contain sensory structures known as Eimer’s organs, usually in the range of a few thousand – star-nosed moles, however, are equipped with 25,000 to 30,000 of these structures studded along the 22 rays of tissue that form it’s namesake organ. As this single appendage is innervated by more than 100,000 sensory neurons, it is thought to be the most sensitive touch organ found on any mammal. By comparison, the human hand contains about 17,000 sensory neurons.
The “nose” itself is a multi-purpose organ, though smelling is not actually a function of this appendage. Moles do smell, and the star-nosed mole can actually smell underwater by blowing bubbles onto objects and inhaling the air for traces of scent. The nose can also be elevated above water while the mole swims to form a breathing apparatus (which we might be tempted to call a “snorkel”). But the real function of the nose is to identify prey in the darkness. The star-nosed mole is active year-round, and the nose is constantly swishing back and forth across the substrate. The rays on the nose have been
observed to differentiate along coarse-focus and fine-focus functions, with the larger rays doing the initial reconnoissance and, upon finding an object of interest, the smallest rays are called in to more thoroughly investigate the object through a series of rapid touches. In an article in The Scientist, Kenneth Catania draws an interesting parallel between this pattern of back-and-forth movement and differential resolution within sensory organs, concluding: “It appears that evolution has repeatedly come to the same solution for constructing a high-acuity sensory system: subdivide the sensory surface into a large, lower-resolution periphery for scanning a wide range of stimuli, and a small, high-resolution area that can be focused on objects of importance.”
The superlatives awarded to the star-nosed mole do not stop with its fabulous nose. As shown in the needlessly dramatic but highly entertaining video (part of National Geographic “World’s Deadliest” youtube series), this particular nose is considered one of the fastest prey-detecting mechanisms, allowing the mole to identify and eat prey in less than 120 milliseconds.
Habitat: Star-nosed moles are semi-aquatic, and are found in swamps, wet fields, and other mucky areas.
Diet: Earthworms are a favorite prey item of the star-nosed mole, but it also consumes aquatic prey such caddisflies, crustaceans, small fish and insect larvae. The star-nosed mole can dive in water for about nine seconds, and hunts in stream bottoms and wet soils.
Catania, Kenneth C. 2002. “A Nose for Touch.” The Scientist. http://www.the-scientist.com/?articles.view/articleNo/32505/title/A-Nose-for-Touch/.
Holland, Mary. 2010. Naturally Curious. North Pomfret, Vermont: Trafalgar Square Books.