Star-nosed mole

The star-nosed mole (Condylura cristata) is a small semiaquatic mole found in moist, low elevation areas in the northeastern parts of North America. It is the only extant member of the tribe Condylurini and genus Condylura. It has more than 25,000 minute sensory receptors in touch organs, known as Eimer's organs, with which this hamster-sized mole feels its way around. With the help of its Eimer's organs, it may be perfectly poised to detect seismic wave vibrations.

The nose is about 1.5 cm (0.59 in) in diameter with its Eimer's organs distributed on 22 appendages. Eimer's organs were first described in the European mole in 1872 by German zoologist Theodor Eimer. Other mole species also possess Eimer's organs, though they are not as specialized or numerous as in the star-nosed mole. Because the star-nosed mole is functionally blind, the snout was long suspected to be used to detect electrical activity in prey animals, though little, if any, empirical support has been found for this hypothesis. The nasal star and dentition of this species appear to be primarily adapted to exploit extremely small prey. A report in the journal Nature gives this animal the title of fastest-eating mammal, taking as little as 120 milliseconds (average: 227 ms) to identify and consume individual food items. Its brain decides in approximately eight milliseconds if prey is edible or not.^{[citation needed]} This speed is at the limit of the speed of neurons.

These moles are also able to smell underwater, accomplished by exhaling air bubbles onto objects or scent trails and then inhaling the bubbles to carry scents back through the nose.

The star-nosed mole lives in wet lowland areas and eats small invertebrates, such as aquatic insects (such as the larvae of caddisflies, midges, dragonflies, damselflies, crane flies, horseflies, predaceous diving beetles, and stoneflies), terrestrial insects, worms (such as earthworms, leeches, and other annelids), mollusks, and aquatic crustaceans, as well as small amphibians and small fish. Condylura cristata has also been found in dry meadows farther away from water. They have also been found in the Great Smoky Mountains as high as 1,676 m (5,499 ft). However, the star-nose mole does prefer wet, poorly drained areas and marshes. It is a good swimmer and can forage along the bottoms of streams and ponds. Like other moles, this animal digs shallow surface tunnels for foraging; often, these tunnels exit underwater. It is active day and night and remains active in winter when it has been observed tunneling through the snow and swimming in ice-covered streams. C. cristata is particularly adept at thermoregulation, maintaining a high body temperature in a wide range of external conditions relative to other Talpid moles. This explains its ability to thrive in cold aquatic environments. Little is known about the social behavior of the species, but it is suspected to be colonial.

This mole mates in late winter or early spring, and the female has one litter of typically four or five young in late spring or early summer. However, females are known to have a second litter if their first is unsuccessful. At birth, each offspring is about 5 cm (2 in) long, hairless, and weighs about 1.5 g (0.053 oz). Their eyes, ears, and star are all sealed, opening and becoming useful only about 14 days after birth. They become independent after about 30 days and are fully mature after 10 months. Predators include the red-tailed hawk, great horned owl, barn owl, screech owl, foxes, weasels, minks, various skunks and mustelids, and large fish such as the northern pike, as well as domestic cats.

Vanderbilt University neuroscientist Kenneth Catania, who has studied star-nosed moles for 20 years, recently turned his research to the study of star-moles as a route to understanding general principles about how human brains process and represent sensory information. He called star-moles "a gold mine for discoveries about brains and behavior in general—and an unending source of surprises".

Comparing the mole's snout to vision, his research showed that whenever the mole touched potential food, it made a sudden movement to position the smallest rays, the twin rays number 11, over the object for repeated rapid touches. He reports: "The similarities with vision were striking. The star movements resembled saccadic eye movements—quick movements of the eyes from one focus point to another—in their speed and time-course. The two 11th rays are over-represented in the primary somatosensory cortex relative to their size, just as the small visual fovea in primates—a small region in the center of the eye that yields the sharpest vision—is over-represented in primary visual cortex." He notes that some bats also have an auditory fovea for processing important echolocation frequencies, suggesting 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 star-shaped nose is a unique organ found only on the star-nosed mole. Living as it does, in complete darkness, the star-nosed mole relies heavily on the mechanical information of its remarkable, specialized nose to find and identify their invertebrate prey without using sight (since moles have small eyes and a tiny optic nerve). This organ is often recognized by its high sensitivity and reaction speed. In only eight milliseconds it can decide whether something is edible — in fact, this is one of the fastest responses to a stimulus in the animal kingdom and is the reason why the star-nosed mole was lately recognized in the Guinness Book of World Records as the world's fastest forager.