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Soil Sidekicks – Star-nosed Mole

August 11, 2015

When you think of an animal that spends most of its life in the soil, what comes to mind? The next Soil Sidekick – the star-nosed mole – is a champion of the underground. Like other moles, it is quite at home among the earthworms, boasting an incredible sense of touch – possibly the best of all mammals.

Star-nosed Mole (Condylura cristata). Photo courtesy of US National Park Service via Wikimedia Commons.

Star-nosed Mole (Condylura cristata). Photo courtesy of US National Park Service via Wikimedia Commons.

The most distinctive feature of this mole is hairless, pink, starred nose. Highly specialized for hunting small prey such as worms, insects, and aquatic invertebrates, the mole’s nose is ringed by 22 fleshy rays that make up the star, which is used for touching and can feel as many as 12 objects per second. The star is equipped with over 25,000 tiny sensory receptors called Eimer’s organs, named after zoologist Theodor Eimer. These unique organs comprise many bumps or domes on the surface of the star.

Almost all moles have Eimer’s organs, but none approach the ultra-sensitivity of this mole’s star, which is about six times more sensitive than the human hand. This appendage is so vital to the star-nosed mole that over half of its brain is dedicated to processing its sensory input. Thanks to the star nose and Eimer’s organs, this champion of the earth has been called the “fastest-eating mammal” because it can take as few as 120 milliseconds to identify whether a food item is edible and consume it. The star’s tentacles can also be held in front of the nostrils to prevent soil from entering the nose, and they are almost constantly moving, feeling and sensing the environment.

Close-up of a mole’s specialized forelimb (European Mole). Photo courtesy of Muséum de Toulouse via Wikimedia Commons.

Close-up of a mole’s specialized forelimb (European Mole). Photo courtesy of Muséum de Toulouse via Wikimedia Commons.

Star-nosed moles are native to Eastern North America up to Canada, and can be found in North Carolina, mostly dwelling in the mountains and Coastal Plain. They live in lowland areas with wet soil such as swamps and marshes, and can also be found along streams or springs in more high-elevation areas such as mountains. They are semi-aquatic so they spend the majority of their lives underground or underwater and are powerful swimmers. Star-nosed moles can even smell in the water, breathing out an air bubble and then inhaling it with their highly sensitive noses to locate aquatic prey. They can do this as quickly as five to ten times per second in order to track prey.

A molehill shows where a mole has been.

A molehill shows where a mole has been.

During the winter, the star-nosed mole’s tail swells to 3-4 times normal size to store fat for the spring breeding season. They are active year-round, including during wintertime. Very little is known about these mammals select a mate, but they appear to be monogamous for one breeding season, mating in late winter or early spring. The female gives birth in late spring/early summer, with an average litter size of five pups. Offspring are born with their eyes, ears, and nose sealed shut, gaining the use of their sensory organs after about 14 days. They are independent after about 30 days, and mature after 10 months. Although not much is known about their lifespans, star-nosed moles are speculated to live about 3-4 years in the wild, and average about 2.5 years in captivity. They are thought to be more social than other moles in North America, forming small colonies of related individuals.

Star-nosed moles are voracious carnivores and are adapted to eat small prey such as earthworms, insects, and crustaceans, also consuming fish and amphibians in aquatic habitats. They prefer to hunt underwater when possible, feasting on a variety of prey including the larvae of pest insects. The star-nosed mole’s predators include birds of prey such as hawks and owls, other mammals such as weasels and skunks, large fish, and domestic cats. Their shallow surface burrows form telltale “molehills” as the mole pushes loose soil up onto the surface.

Contrary to popular belief, moles (including the star-nosed mole) are carnivorous, so they are not the ones munching on the vegetables in your garden – voles are typically the culprits. These master earth excavators are very much at home in the soil, especially in wet areas. If you happen to be in a marsh and see the star-nosed mole’s telltale molehill, one of these amazing mammals may be nearby, using its incredible nose to hunt its next meal. After all, the nose always knows best!

Soil Sidekicks is an inside scoop starring animals that live in and around the soil. Did you know that there are more living creatures in a shovelful of rich soil than there are people on the planet? Get the dirt on where the Sidekicks live and discover more about the soil that sustains us at Dig It! The Secrets of Soil, through August 16.

Claire Carrington is a Museum Public Relations intern, and currently a senior at Campbell University.

Thanks to Lisa Gatens, Curator of Mammals for guidance.

First photo: By US National Park Service. Public Domain, via Wikimedia Commons.

Second photo: By Muséum de ToulouseCC BY-SA 3.0, via Wikimedia Commons.

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