Create a list of articles to read later. You will be able to access your list from any article in Discover.
You don't have any saved articles.
Why do star-nosed moles have a ‘hand’ on their face?
The star-nosed mole, Condylura cristata, is one of 39 mole species. Moles are small, furry, underground, tunnel-dwelling mammals that feast mostly on insects.
Star-nosed moles share many similarities with other moles in the Talpidae family but are the only ones with a distinctive star-shaped nose.
Like all moles, star-nosed moles are small mammals with cylindrical bodies. They also share stocky limbs and large, spade-like forepaws that they use to dig networks of tunnels through the earth.
Star-nosed moles have a scaly tail and short, waterproof fur that’s dark brown-black on top and lighter on the belly.
But the first thing you probably notice about this animal is its unusual nose. The hairless tentacles, or rays, fanning out around its nostrils resemble a many-pointed star – giving the species its name.
The first thing you probably notice about the star-nosed mole is its eponymous facial feature. It looks strange but is actually super sensitive and helps them survive. © Agnieszka Bacal/ Shutterstock
‘The star is a cluster of 22 tendrils on the mole’s face,’ explains researcher Dr Gustavo Burin. ‘They’re extremely sensitive to touch and are constantly moving about to find prey.’
When looking for food, the star-nosed mole moves its star so quickly that it’s just a blur to our eyes. It touches up to 12 objects per second.
Where do star-nosed moles live?
Star-nosed moles live in eastern North America, from northern Florida in the USA, up into southeastern Canada.
They prefer wetland habitats with moist soil, such as marshes, swamps and peatlands. This distinguishes them from many other mole species who prefer drier soils.
Star-nosed moles are semiaquatic and prefer to hunt for prey in rivers, lakes and ponds. They sometimes dig underground tunnels that open directly into a body of water.
Star-nosed moles use their large forepaws to make alternate strokes through the water, which causes them to swim in a zigzag pattern. © Agnieszka Bacal/Shutterstock
How do their noses work?
Star-nosed moles have a good sense of smell – also called the olfactory sense – but they rely primarily on their sense of touch to navigate their surroundings. This is where their unusual star-shaped nose comes in.
Super-sensitive microscopic touch organs called Eimer’s organs cover the 22 rays of the nose. There are 25,000 of these special touch organs, containing 100,000 nerve endings, despite the nose only being about one centimetre across.
This extremely high concentration of Eimer’s organs gives the star-nosed mole the best sense of touch of any mammal. By comparison, our hands have 17,000 nerve endings.
The star-nosed mole’s star is sometimes likened to an eye on the tip of their nose.
‘These 22 different tendrils on their star allow them to understand where different objects are in space – be that soil, an earthworm, or something else,’ Gustavo explains. ‘It’s similar to how bats use sonar to identify where obstacles are and where prey is while they’re flying.’
The star has a structure called a fovea, which is its most sensitive point. Our eyes also have fovea. But, since the mole uses its star for touching things rather than seeing, the organ the star actually most resembles is a highly sensitive hand.
Are star-nosed moles blind?
A common misconception is that moles are blind. Like other moles, star-nosed moles have small eyes that are often so hidden in their fur that they look like they have no eyes at all.
But while their eyesight is weak, it’s important for helping moles to detect light and dark. This is particularly important for star-nosed moles, who spend more time above ground than many other mole species.
Star-nosed moles are small – about twice the weight of a mouse.
Can star-nosed moles swim?
Most moles can swim, but the star-nosed mole is a particularly strong swimmer. They have evolved twice the lung capacity of other mole species and have longer tails, which help them steer in the water.
As well as an amazing sense of touch, the star-nosed mole can also ‘sniff’ underwater.
As they swim along, they blow an air bubble that captures scent particles in the water. They then suck the air bubble back into their nose to sample the particles. This allows them to follow the scent of their prey in the water.
Star-nosed moles use their remarkable hand-like nose to prevent these bubbles from bursting or drifting away before they can suck them back into their nostrils.
Star-nosed moles and American water shrews are the only two mammals known to have this amazing ability.
Understanding how they do it could be extremely helpful to us, too. ‘This remarkable ability could have applications in engineering,’ Gustavo says. ‘Research into this mechanism might help us develop tools for detecting contamination in very deep water or even in the air.’
Dr Gustavo Burin explains how star-nosed moles can sniff out their prey underwater.
What do star-nosed moles eat?
Star-nosed moles have a varied diet. They snack on worms – both terrestrial worms that wriggle through the walls of their burrows and aquatic worm species such as leeches. They also dine on aquatic insects, such as midges and dragonflies, as well as on crustaceans, molluscs and even small fish.
All moles are voracious eaters, but the star-nosed mole’s amazing nose allows them to identify and eat as many as five items of prey in a single second. In fact, they can eat more than half of their body weight in a single day.
Did you know?
The star-nosed mole holds the Guinness World Record for the fastest-eating mammal.
From identifying a food item to eating it takes them 230 milliseconds on average. The fastest recorded is 120 milliseconds. That’s as fast as you blink!
Star-nosed moles are also food for other animals. They’re eaten by frogs, fishes, raptors, such as owls and hawks, and mammals, such as skunks and weasels.
The star-nosed mole is important both as a predator and prey species in its wetland habitats. © J.A. Dunbar/ Shutterstock
How do star-nosed moles reproduce?
We don’t know too much about the life cycle of the star-nosed mole because they spend so much time underground.
We do know that, like other moles, star-nosed moles reproduce one litter of pups every breeding season, with an average of five young.
In the wild, we think star-nosed moles live for about 3–4 years.
How did star-nosed moles evolve?
Their star nose may have evolved in response to their wetland environment. The moist soil contains a lot of prey. Their super-sensitive star allows them to sense and eat more prey in a given volume of soil than a competitor with less finely attuned senses.
‘Genetic variation in the population started to generate individuals who had more sensitive organs, and they ended up performing better when tracking prey.’ Gustavo explains. ‘Over time, the tendrils of the star-nose became a more efficient way to look for prey, because it’s easier to touch prey, than to track them via smelling. Eventually this resulted in the star nose.’
The relative softness of wetland soil may also have made the remarkable star-nose adaptation possible. Other moles are typically found in drier, rougher soil. This soil would damage the star’s thin, tender sensory organs more easily, and therefore, such an adaptation might not have developed.
While all moles dig molehills, the star-nosed mole’s preference for wetland habitats means they’re less likely to dig up an unfortunate gardener’s lawn than species like the European mole. © kubais/ Shutterstock
Why are star-nosed moles important?
Star-nosed moles are both an important food source in their habitats and an important predator, especially of aquatic invertebrates.
Though we rarely see them, they’re relatively common. Star-nosed moles are labelled as Least Concern on the International Union for Conservation of Nature’s Red List of Threatened Species. However, this remarkable species still needs and deserves our protection.
‘There’s nothing else in nature like the star-nosed mole,” says Gustavo. ‘They also live in areas that are typically very impacted by human activity – areas such as lake shores and riverbanks. By protecting them you’re also protecting so many other species and that whole landscape.’
