Condylura cristata
star-nosed mole

Condylura cristata is native to eastern North America. This species ranges further north than other New World talpids, reaching about 55°N latitude in Québec and Newfoundland. The range extends from the Atlantic Ocean west to Manitoba and North Dakota and south to Ohio and Virginia. Condylura cristata is also found along the Atlantic coast south to Georgia as well as throughout the Appalachian mountains. (Kurta, 1995)

Star-nosed moles are found in a variety of habitats with moist soil. Unlike other North American moles, Condylura cristata prefers areas of poor drainage, including both coniferous and deciduous forests, clearings, wet meadows, marshes and peatlands. Condylura cristata also inhabits the banks of streams, lakes and ponds, into which it ventures for food. Although it prefers wet areas, this species has been found in dry meadows as far as 400 m from water. Condylura cristata can be found along the coast and is known from elevations up to 1676 m in the Great Smoky Mountains. (Baker, 1983; Hamilton, 1931; Kurta, 1995; Linzey and Brecht, 2004; Lyon, 1936)

Condylura cristata is one of the most distinctive mammal species. Its nose is hairless and is ringed by a unique 'star' of 22 pink, fleshy tentacles. The star is bilaterally symmetrical with 11 appendages per side that vary in length from between 1 and 4 mm. Condylura cristata ranges from 175 to 205 mm in total length and weighs between 35 and 75 g. Like other moles it has a stout, roughly cylindrical body with heavily-built forelimbs, broad feet and large claws. Its hair is short, dense and coarser than that of other moles. The pelage is dark brown to black on the back and lighter brown underneath. The tail is 65 to 85 mm long, constricted at the base, annulated, scaly and covered with coarse hair. During winter the tail swells 3 to 4 times its normal diameter. Females have 8 mammae, and the testes of males can be 8.8% of the total body weight during the mating season. Sexes are otherwise similar in appearance. (Baker, 1983; Hamilton, 1931; Kurta, 1995; Linzey and Brecht, 2004; Lyon, 1936; Van Vleck, 1965)

Star-nosed moles are the sole living member of the genus Condylura. There are two described subspecies: C. cristata cristata in the north and C. cristata parva in the south. The latter subspecies is distinguished primarily by its smaller size. Two fossil species, C. kowalskii and C. izabellae, are known from the middle Pliocene of Poland. (Petersen and Yates, 1980; Skoczen, 1979)

Not much is known about the lifespan of Condylura cristata in the wild. Since a female's reproductive effort is limited to only 1 litter per year, is is speculated that C. cristata may have a relatively long lifespan for a mammal of its size, perhaps 3 to 4 years. Some star-nosed moles have lived 2 years in captivity. (Baker, 1983; Gould, McShea, and Grand, 1993; Kurta, 1995)

Like many other moles, C. cristata is fossorial, digging a network of tunnels through moist soil. The tunnels are 3.3 to 7.6 cm wide, typically wider than tall, and can extend as much as 270 m along the edge of a suitably wet habitat. The mole digs shallow surface tunnels for foraging but, unlike the eastern mole, it does not dig deeper burrows for protection in the winter. The surface tunnels vary in depth from 3 to 60 cm, only occasionally coming close enough to the surface to cause a raised ridge. The loose soil dug from the tunnels is pushed out onto the surface, forming 'molehills' that can be 60 cm wide and 15 cm high. A spherical nest about 13 cm in diameter is constructed in the tunnel system above the water line, often under a log or similar protective object, and lined with dry leaves or grass. Unlike other North American moles, C. cristata is semiaquatic, so many of its tunnels open under the surface of a stream or lake. Its fossorial forelimbs also make good paddles and it swims underwater with alternate strokes of both front and hind feet, resulting in a characteristic zigzag motion. Condylura cristata is also more active on the surface than other moles, using runways (often made by other small mammals) through meadow or marsh vegetation. Condylura cristata is active throughout the winter, burrowing through snow and even swimming under the ice of frozen ponds. (Baker, 1983; Fisher, 1885; Hamilton, 1931; Hickman, 1983; Kurta, 1995; Lyon, 1936; Merriam, 1884; Rust, 1966; Tenny, 1871; Wiegert, 1961)

The star is used in a number of different activities. When C. cristata is burrowing, the tentacles are held forward over the nostrils to prevent soil from entering the nose. This behavior also occurs while consuming prey. During normal foraging activity, the tentacles are constantly being used to feel the mole's surroundings, moving so rapidly that they appear as a blur of motion, touching as many as 12 objects per second. The upper two tentacles are held more rigidly, straight out in front of the nose. When C. cristata encounters a potential prey item with its star, it focuses the lowest, shortest tentacles on the prey. Using these supersensitive organs, identification of prey can be made in under half a second. (Baker, 1983; Catania, 2002; Hamilton, 1931)

Home Range

The home range of an individual star-nosed mole is thought to be less than 4000 square meters. Condylura cristata is more social than other moles in eastern North America and is believed to form small, loose colonies of related individuals. It is not known if more than one mole will share a network of tunnels, other than paired males and females during the breeding season. In favorable habitat, the density of moles may be as great as 75 per hectare, though 25 or fewer per hectare is more common. (Baker, 1983; Eadie and Hamilton, 1956; Hamilton, 1931)

Condylura cristata, equipped with its unique star, has perhaps the best sense of touch of any mammal. Each of the 22 appendages that make up the star is completely covered with tiny papillae known as Eimer's organs. Each Eimer's organ contains 3 types of tactile receptors, 2 of which are found in the skin of other mammals. The third type is unique to the star-nosed mole and is thought to allow the mole to identify objects by their microscopic texture. The star possesses over 25,000 Eimer's organs in a space less than 1 square cm, making it incredibly sensitive. A vast portion of the mole's brain is devoted to processing this tactile information. The shortest pair of tentacles at the bottom of the star have the greatest density of Eimer's organs and are apparently used to identify prey items. Although it has not been demonstrated conclusively, it is thought that the star may also be used to detect faint electrical signals from the star-nosed mole's aquatic prey. Laboratory tests have shown that C. cristata seems to be drawn to batteries placed underwater as well as to the areas of strongest electrical activity on prey items. If true, C. cristata and the platypus (Ornithorhynchus anatinus) are the only mammals known to possess this ability.

Although externally visible, the eyes of C. cristata may only be useful for sensing light and dark. Its hearing seems to be excellent, as the external ear openings are much larger than those of other North American species. Its sense of smell is probably also fairly well-developed. Young star-nosed moles make some high-pitched vocalizations and adults are known to make wheezing sounds. There is little information available on how individuals communicate with each other. (Baker, 1983; Catania, 2002; Gould, McShea, and Grand, 1993; Hamilton, 1931; Van Vleck, 1965)

Condylura cristata feeds primarily on invertebrates. Like other fossorial moles, C. cristata patrols its burrows searching for earthworms that enter through the walls. When it has access to a body of water, however, C. cristata prefers to hunt aquatic prey. About half of its diet consists of worms (Annelida), and 80% of these are aquatic species such as leeches. Aquatic insects make up another 30% of its diet, including the larvae of caddisflies (Trichoptera), midges (Chironomidae), dragonflies and damselflies (Odonata), crane flies (Tipulidae), horse flies (Tabanidae), predacious diving beetles (Dytiscidae) and stoneflies (Plecoptera). Condylura cristata will also take occasional terrestrial insects, aquatic crustaceans, mollusks and small fish. (Baker, 1983; Hamilton, 1931; Kurta, 1995; Lyon, 1936; Rust, 1966)

Condylura cristata is preyed upon by a number of different animals. Since this species spends time underwater as well as more time above ground than other moles, it is more vulnerable to predation. From the air, C. cristata is hunted by owls both large and small as well as by hawks during the day. On the ground, both domestic dogs and cats will capture star-nosed moles. A number of mustelids prey on C. cristata, including skunks, weasels, and the fisher. Another mustelid, the mink, is semiaquatic and may hunt Condylura cristata underwater. Other known aquatic predators include the bullfrog and largemouth bass. (Baker, 1983; Christian, 1977; Hamilton, 1931; Kurta, 1995; Linzey and Brecht, 2004)

Condylura cristata is an important part of many wetland ecosystems. It provides food for a number of carnivores and is a voracious predator of aquatic invertebrates. By tunneling through moist ground, C. cristata provides aeration to the roots of plants which might otherwise be trapped in anoxic soil. (Baker, 1983; Kurta, 1995; Lyon, 1936)

Since C. cristata inhabits poorly-drained wet areas, it is not often found in areas that humans frequent. However, it may occasionally extend its tunnels into lawns adjacent to wetlands, damaging the sod. Trapping is generally an effective way to remove star-nosed moles. (Baker, 1983; Hamilton, 1931)

Condylura cristata benefits humans by preying on the larvae of pest insects. They also aerate the soil of plants that may be beneficial to humans. (Baker, 1983)

Condylura cristata is a relatively common species, and since it is rather inconspicuous and inhabits wet areas, humans do not generally impact this species directly. Large numbers are sometimes caught in muskrat traps, but this does not seem to negatively effect their population size. However, since C. cristata is dependent on wetlands for survival, the ongoing destruction of wetlands to make way for an expanding human population may affect the status of this species in the future. (Baker, 1983; Hamilton, 1931)