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Star-nosed mole

life science Maturity 5-7 Next article →

The star-nosed mole, known scientifically as Condylura cristata, is a unique semiaquatic mammal. It lives in moist, low-elevation areas across northeastern North America. This species is the only living member of its genus and tribe. While it can be found in dry meadows, it prefers wet marshes and poorly drained areas. It is a skilled swimmer that forages along the bottoms of ponds and streams. The mole is also highly active during the winter. It can tunnel through snow and swim in streams covered by ice. This is possible because the mole is excellent at thermoregulation, which means it can maintain a high body temperature even in cold water.

Condylura cristata MHNT.INS.6
Condylura cristata MHNT.INS.6

The most striking feature of this mole is its nose. The snout is shaped like a star with 22 fleshy appendages, or tendrils. These appendages do not have muscles or bones of their own. Instead, they are controlled by tendons attached to muscles on the skull. The star is about 2.7 centimeters across, making it slightly smaller than a human fingertip. The surface of this star is covered in over 25,000 tiny sensory receptors called Eimer's organs. These organs were first described in 1872 by the German zoologist Theodor Eimer. While other moles have these organs, none have them in such high numbers. This makes the star-nosed mole's nose about six times more sensitive than a human hand.

Condylura cristata MHNT.INS.6
Condylura cristata MHNT.INS.6

The star-nosed mole uses its nose like a "tactile eye" to navigate in the dark. Because the mole is functionally blind, it relies on mechanical information to find prey. The star is divided into two main parts: a high-resolution central fovea and a lower-resolution periphery. The fovea consists of the 11th pair of rays, which are the shortest appendages. When the mole touches something interesting, it makes rapid movements to position these 11th rays over the object. Neuroscientist Kenneth Catania has noted that these movements are very similar to saccadic eye movements in humans. Saccades are the quick jumps our eyes make when moving between focus points. This allows the mole to focus on important details with extreme precision.

Condylura cristata MHNT.INS.6
Condylura cristata MHNT.INS.6

This specialized sensory system allows the mole to be the fastest-eating mammal in the world. It can identify and consume a single food item in as little as 120 milliseconds. On average, the process takes about 227 milliseconds. The mole's brain is incredibly efficient at processing this information. It takes only eight milliseconds for the brain to decide if a piece of prey is edible. This speed is near the physical limit of how fast neurons can function. To put this in perspective, the entire process of responding to touch and sending a motor command takes only 25 milliseconds. In contrast, a similar process in a human takes about 600 milliseconds.

Condylura cristata MHNT.INS.6
Condylura cristata MHNT.INS.6

The mole's brain is physically organized to support this incredible speed. About 52% of the mole's somatosensory cortex is dedicated to processing information from the nose. This means more than half of its brain is focused on its sense of touch. The brain uses a somatotopic organization, meaning parts of the nose are mapped to specific areas of the brain. Interestingly, the 11th pair of rays has a larger representation in the brain than its physical size would suggest. This is because the fovea is so vital for survival. The brain even shows visible stripes that represent the different rays of the star.

Condylura cristata MHNT.INS.6
Condylura cristata MHNT.INS.6

The diet of the star-nosed mole consists of many small invertebrates. It eats aquatic insects like caddisflies, midges, and dragonflies. It also consumes larvae from damselflies, crane flies, and horseflies. Other food sources include earthworms, leeches, mollusks, and aquatic crustaceans. Sometimes, the mole will even eat small fish or amphibians. To find food underwater, the mole uses a clever smelling technique. It exhales air bubbles onto an object or a scent trail. It then inhales those bubbles to carry the scents back into its nose.

Condylura cristata MHNT.INS.6
Condylura cristata MHNT.INS.6

Despite its specialized skills, the star-nosed mole faces many predators. It must avoid birds like red-tailed hawks, great horned owls, and various screech owls. Land predators include foxes, weasels, minks, and skunks. Even large fish like the northern pike or domestic cats can be a threat. To protect itself, the mole digs shallow tunnels for foraging. These tunnels often exit underwater, allowing the mole to move safely through its wet environment. The mole's life is a constant cycle of rapid sensing, eating, and hiding to survive in the North American wetlands.

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File:Condylura cristata MHNT.INS.6.jpg
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