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Overview

Brief Summary

Description

No other mammal in the world looks like the star-nosed mole, which has 22 fingerlike appendages surrounding its nostrils. It has recently been discovered that these very sensitive tactile organs are used for object manipulation, and perhaps even for detection of electrical signals emitted by prey in the water. Star-nosed moles are able swimmers, and often forage in water for small fish and aquatic invertebrates, including insects, mollusks, and crustaceans.

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  • Original description: Linnaeus, C., 1758.  Systema Naturae per regna tria naturae, secundum classis, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Tenth Edition, Vol. 1, p.  53. Laurentii Salvii, Stockholm, 824 pp.
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Distribution

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.

Biogeographic Regions: nearctic (Native )

  • Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor: The University of Michigan Press.
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Range Description

This species is primarily distributed in the northeastern United States and southeastern Canada, from Labrador, Quebec, and Nova Scotia westward to eastern North Dakota and southeastern Manitoba, and south to Minnesota, Wisconsin, Indiana, and Ohio, south in the Appalachians to the Great Smoky Mountains, and south along the Atlantic coast to southeastern Georgia and the northern edge of Florida. It ranges farther north than all other native mole species.
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Primarily distributed in the northeastern U.S. and southeastern Canada. Labrador, Quebec, and Nova Scotia westward to eastern North Dakota and southeastern Manitoba, and south to Minnesota, Wisconsin, Indiana, and Ohio, south in the Appalachians to the Great Smoky Mountains (e.g., Beane 1995, Brimleyana 22:77-86), and south along the Atlantic coast to southeastern Georgia. Ranges farther north than all other native mole species.

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Geographic Range

Condylura_cristata is native to eastern North America. This species ranges further north than other New World Talpidae, 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.

Biogeographic Regions: nearctic (Native )

  • Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor: The University of Michigan Press.
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Physical Description

Morphology

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.

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.

Range mass: 35 to 75 g.

Range length: 175 to 205 mm.

Sexual Dimorphism: sexes alike

Other Physical Features: endothermic ; bilateral symmetry

Average basal metabolic rate: 0.615 W.

  • Petersen, K., T. Yates. 1980. Condylura cristata. Mammalian Species, 129: 1-4.
  • Skoczen, S. 1979. Condylura Illiger, 1811 (Insectivora, Talpidae) a new genus of fossil mole for Poland and Old World. Przeglad Zoologiczny, 23/2: 167-171.
  • Van Vleck, D. 1965. The anatomy of the nasal rays of Condylura cristata . Journal of Mammalogy, 46/2: 248-253.
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Physical Description

Star nosed moles are one of the most distinctive types of mammal. Their noses are hairless and ringed by a unique 'star' of 22 pink, fleshy tentacles. The star has 11 appendages per side that vary in length from 1 to 4 mm. This species 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. During winter the tail swells 3 to 4 times its normal diameter.

Range mass: 35 to 75 g.

Range length: 175 to 205 mm.

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 0.615 W.

  • Petersen, K., T. Yates. 1980. Condylura cristata. Mammalian Species, 129: 1-4.
  • Skoczen, S. 1979. Condylura Illiger, 1811 (Insectivora, Talpidae) a new genus of fossil mole for Poland and Old World. Przeglad Zoologiczny, 23/2: 167-171.
  • Van Vleck, D. 1965. The anatomy of the nasal rays of Condylura cristata . Journal of Mammalogy, 46/2: 248-253.
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Size

Length: 21 cm

Weight: 75 grams

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Size in North America

Sexual Dimorphism: None

Length:
Range: 132-230 mm

Weight:
Range: 40-85 g
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Ecology

Habitat

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.

Range elevation: 0 to 1676 m.

Habitat Regions: temperate ; terrestrial ; freshwater

Terrestrial Biomes: taiga ; forest

Aquatic Biomes: lakes and ponds; rivers and streams

Wetlands: marsh ; swamp ; bog

Other Habitat Features: riparian

  • Baker, R. 1983. Michigan Mammals. Detroit: Michigan State University Press.
  • Hamilton, W. 1931. Habits of the star-nosed mole, Condylura cristata . Journal of Mammalogy, 12/4: 345-355.
  • Linzey, D., C. Brecht. 2004. "Condylura cristata (Linnaeus); Star-nosed Mole" (On-line). Discover Life. Accessed February 09, 2004 at http://www.discoverlife.org/nh/tx/Vertebrata/Mammalia/Talpidae/Condylura/cristata/.
  • Lyon, M. 1936. Mammals of Indiana. American Midland Naturalist, 17/1: 1-373.
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Habitat and Ecology

Habitat and Ecology
The star-nosed mole is seldom far from bodies of water. It prefers wet soils in flood plains, swamps, meadows, and other openings near water. It is a good swimmer and diver, and may be active in water under ice in winter. It is more dependent on water in winter when the ground is frozen. It occasionally occurs in leaf mold on the floor of dense forests. Tunnels may be shallow or deep and may open at the ground surface or under water. The nest usually is placed in a hummock, under a stump or log, in humus among rotten tree roots, or in other areas above high water, often near a stream. Gestation lasts about 45 days. Parturition occurs in spring or early summer (late March-early August in central New York). Litter size is three to seven, with an average of five to six, with one litter per year. They sexually mature in 10 months. They may maintain the pair bond throughout the breeding season.

In some areas this species eats mainly aquatic invertebrates; benthic prey may constitute entire winter diet. Earthworms are abundant in the diet in some areas (Peterson and Yates 1980). It is active all year, and active day or night, but may be more active at night.

Systems
  • Terrestrial
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Comments: Seldom far from bodies of water. Prefers wet soils in flood plains, swamps, meadows, and other openings near water. Good swimmer and diver. May be active in water under ice in winter. More dependent on water in winter when ground is frozen. Occasionally occurs in leaf mold on the floor of dense forests. Tunnels may be shallow or deep and may open at ground surface or under water.

Nest usually is placed in a hummock, under a stump or log, in humus among rotten tree roots, or in other areas above high water, often near a stream.

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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.

Range elevation: 0 to 1676 m.

Habitat Regions: temperate ; terrestrial ; freshwater

Terrestrial Biomes: taiga ; forest

Aquatic Biomes: lakes and ponds; rivers and streams

Wetlands: marsh ; swamp ; bog

Other Habitat Features: riparian

  • Baker, R. 1983. Michigan Mammals. Detroit: Michigan State University Press.
  • Hamilton, W. 1931. Habits of the star-nosed mole, Condylura cristata . Journal of Mammalogy, 12/4: 345-355.
  • Linzey, D., C. Brecht. 2004. "Condylura cristata (Linnaeus); Star-nosed Mole" (On-line). Discover Life. Accessed February 09, 2004 at http://www.discoverlife.org/nh/tx/Vertebrata/Mammalia/Talpidae/Condylura/cristata/.
  • Lyon, M. 1936. Mammals of Indiana. American Midland Naturalist, 17/1: 1-373.
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

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.

Animal Foods: fish; insects; mollusks; terrestrial worms; aquatic or marine worms; aquatic crustaceans

Primary Diet: carnivore (Vermivore)

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Comments: In some areas eats mainly aquatic invertebrates; benthic prey may constitute entire winter diet. Earthworms are abundant in the diet in some areas (Peterson and Yates 1980). May use an electrical sense to detect prey (Gould et al., 1993, J. Mamm. 74:108-116).

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Food Habits

Star-nosed moles feed primarily on invertebrates. Like other moles that live underground, 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.

Animal Foods: fish; insects; mollusks; terrestrial worms; aquatic or marine worms; aquatic crustaceans

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Associations

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.

Ecosystem Impact: soil aeration

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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.

Known Predators:

  • Christian, D. 1977. An Occurrence of Fish Predation on a Star-nosed Mole. Jack-Pine Warbler, 55/1: 43.
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Ecosystem Roles

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 oxygen to the roots of plants which might otherwise be trapped in compacted soil with no oxygen.

Ecosystem Impact: soil aeration

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Predation

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 Mustelidae 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.

Known Predators:

  • great horned owls (Bubo_virginianus)
  • eastern screech owls (Otus_asio)
  • barred owls (Strix_varia)
  • barn owls (Tyto_alba)
  • saw-whet owls (Aegolius_acadicus)
  • red-tailed hawks (Buteo_jamaicensis)
  • red-shouldered hawks (Buteo_lineatus)
  • rough-legged hawks (Buteo_lagopus)
  • broad-winged hawks (Buteo_platypterus)
  • domestic dogs (Canis_lupus_familiaris)
  • red foxes (Vulpes_vulpes)
  • domestic cats (Felis_silvestris)
  • striped skunks (Mephitis_mephitis)
  • fishers (Martes_pennanti)
  • long-tailed weasels (Mustela_frenata)
  • American minks (Mustela_vison)
  • bullfrogs (Rana_catesbeiana)
  • largemouth bass (Micropterus_salmoides)

  • Christian, D. 1977. An Occurrence of Fish Predation on a Star-nosed Mole. Jack-Pine Warbler, 55/1: 43.
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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

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Global Abundance

10,000 to >1,000,000 individuals

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General Ecology

Home range probably is about 0.4 ha (Banfield 1974). Density of 4-7 per ha has been recorded for swampland (Hamilton 1931). In New York, 2-3 per ha were found during winter. Gregarious.

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Life History and Behavior

Behavior

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.

Perception Channels: visual ; tactile ; acoustic ; chemical

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Communication and Perception

Equipped with its unique star, star-nosed mole have perhaps the best sense of touch of any Mammalia. Each of the 22 appendages that make up the star is completely covered with tiny, sensitive projections known as Eimer's organs. The star possesses over 25,000 Eimer's organs in a space less than 1 square cm, making it incredibly sensitive. The star may also be able to detect faint electrical signals from the star-nosed mole's aquatic prey. If true, C. cristata and the platypus (Ornithorhynchus_anatinus) are the only mammals known to possess this ability.

The eyes of C. cristata may only be useful for sensing light and dark. Its hearing seems to be excellent, however. Its sense of smell is probably also fairly well-developed. Young star-nosed moles make some high-pitched calls and adults are known to make wheezing sounds. There is little information available on how individuals communicate with each other.

Perception Channels: visual ; acoustic

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Cyclicity

Comments: Active all year. Active day or night; may be more active at night.

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Life Expectancy

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.

Range lifespan

Status: captivity:
2 (high) years.

Typical lifespan

Status: wild:
3 to 4 years.

Average lifespan

Status: wild:
3 to 4 years.

Average lifespan

Status: captivity:
2.5 years.

  • Gould, E., W. McShea, T. Grand. 1993. Function of the star in the star-nosed mole, Condylura cristata . Journal of Mammalogy, 74/1: 108-116.
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Lifespan/Longevity

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.

Range lifespan

Status: captivity:
2 (high) years.

Typical lifespan

Status: wild:
3 to 4 years.

Average lifespan

Status: wild:
3 to 4 years.

Average lifespan

Status: captivity:
2.5 years.

  • Gould, E., W. McShea, T. Grand. 1993. Function of the star in the star-nosed mole, Condylura cristata . Journal of Mammalogy, 74/1: 108-116.
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Lifespan, longevity, and ageing

Maximum longevity: 2.5 years (captivity) Observations: Considering its small reproductive output, it has been speculated that these animals may live up to 3 to 4 years. Record longevity in captivity, however, is only 2.5 years (Richard Weigl 2005). Further studies may be necessary.
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Reproduction

Condylura cristata appears to be monogamous for one breeding season. Males and females are thought to pair up as early as autumn and remain together through the mating season in March and April. Little is known about how the star-nosed mole finds or attracts a mate.

Mating System: monogamous

Condylura cristata mates in the spring from about mid-March through April. Gestation lasts approximately 45 days, and young are born in late April through mid-June. Females produce one litter of offspring per year of between 2 and 7 young, though 5 is a typical litter size. If a female's first reproductive effort was unsuccessful, she may mate again, producing a litter as late as July. At birth the young are hairless, are approximately 49 mm long and weigh about 1.5 g. The eyes and ears are closed and the tentacles of the star are folded back along the rostrum. Eyes, ears and star become functional after about 2 weeks. Young are independent at 30 days and reach maturity at 10 months.

Breeding interval: Star nosed moles breed once yearly, though females may mate again if their first litter is unsuccessful.

Breeding season: Star nosed moles breed from mid-March through April.

Range number of offspring: 2 to 7.

Average number of offspring: 5.

Average gestation period: 45 days.

Average weaning age: 30 days.

Average time to independence: 30 days.

Average age at sexual or reproductive maturity (female): 10 months.

Average age at sexual or reproductive maturity (male): 10 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous

Average number of offspring: 4.4.

Average age at sexual or reproductive maturity (male)

Sex: male:
304 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
304 days.

Little is known about parental investment in Condylura cristata, but there is likely no post-weaning care.

Parental Investment: altricial

  • Baker, R. 1983. Michigan Mammals. Detroit: Michigan State University Press.
  • Eadie, W., W. Hamilton. 1956. Notes on reproduction in the star-nosed mole. Journal of Mammalogy, 37/2: 223-231.
  • Hamilton, W. 1931. Habits of the star-nosed mole, Condylura cristata . Journal of Mammalogy, 12/4: 345-355.
  • Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor: The University of Michigan Press.
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Gestation lasts about 45 days. Parturition occurs in spring or early summer (late March-early August in central New York). Litter size is 3-7, average 5-6. One litter per year. Sexually mature in 10 months. May maintain pair bond throughout the breeding season.

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Star-nosed moles appear to have only one mate each breeding season. Males and females are thought to pair up as early as autumn and remain together through the mating season in March and April. Little is known about how the star-nosed mole finds or attracts a mate.

Mating System: monogamous

Star nosed moles mate in the spring from about mid-March through April. Pregnancy lasts approximately 45 days, and young are born in late April through mid-June. Females produce one litter of offspring per year of between 2 and 7 young, though 5 is a typical litter size. If a female's first reproductive effort is unsuccessful, she may mate again, producing a litter as late as July. At birth the young are hairless, the eyes and ears are closed and the tentacles of the star are folded back along the snout. The eyes, ears and star become functional after about 2 weeks. Young are independent at 30 days and reach maturity at 10 months.

Breeding interval: Star nosed moles breed once yearly, though females may mate again if their first litter is unsuccessful.

Breeding season: Star nosed moles breed from mid-March through April.

Range number of offspring: 2 to 7.

Average number of offspring: 5.

Average gestation period: 45 days.

Average weaning age: 30 days.

Average time to independence: 30 days.

Average age at sexual or reproductive maturity (female): 10 months.

Average age at sexual or reproductive maturity (male): 10 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average number of offspring: 4.4.

Average age at sexual or reproductive maturity (male)

Sex: male:
304 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
304 days.

Little is known about parental investment in Condylura cristata, but there is likely no post-weaning care.

Parental Investment: altricial

  • Baker, R. 1983. Michigan Mammals. Detroit: Michigan State University Press.
  • Eadie, W., W. Hamilton. 1956. Notes on reproduction in the star-nosed mole. Journal of Mammalogy, 37/2: 223-231.
  • Hamilton, W. 1931. Habits of the star-nosed mole, Condylura cristata . Journal of Mammalogy, 12/4: 345-355.
  • Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor: The University of Michigan Press.
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Evolution and Systematics

Functional Adaptations

Functional adaptation

Snout detects pressure: star-nosed mole
 

The snout of talpids can detect pressure and other sensory input thanks to the Eimer's gland, a mechanosensory organ.

   
  "Talpids also possess an Eimer's gland, a mechanosensory organ present on the rhinarium. This organ is highly sensitive and responds to the onset and offset of pressure, to sustained depression of the epidermis, and to changes in the angle of the stimulation. This organ may be used to detect prey by determining surface texture, and in the star-nosed moles the Eimer's gland may detect the electrical fields of prey in water." (Fowler and Miller 2003:304)
  Learn more about this functional adaptation.
  • Fowler, ME; Miller, RE. 2003. Zoo and Wild Animal Medicine. Philadelphia: W.B. Saunders Co.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Condylura cristata

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 9
Species With Barcodes: 1
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Conservation

Conservation Status

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.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
NatureServe (Hammerson, G.)

Reviewer/s
Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern because it is very widespread, common, there are no major threats, and its population is not currently in decline.
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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Reasons: Common over large range in southeastern Canada and the eastern U.S.

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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 Ondatra zibethicus 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.

IUCN Red List of Threatened Species: least concern

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

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Population

Population
This species is common over a large range in southeastern Canada and the eastern United States. Its home range probably is about 0.4 ha (Banfield 1974). A density of four to seven per ha has been recorded for swampland (Hamilton 1931). In New York, two to three per ha were found during winter.

Population Trend
Stable
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Threats

Major Threats
There are no major threats to this species.
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Management

Conservation Actions

Conservation Actions
The range of this species includes several protected areas.
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Relevance to Humans and Ecosystems

Benefits

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.

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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.

Positive Impacts: controls pest population

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Economic Importance for Humans: Negative

Since star-nosed moles inhabit poorly-drained wet areas, it is not often found in areas near humans. However, these moles may occasionally extend their tunnels into lawns adjacent to wetlands, damaging the sod. Trapping is generally an effective way to remove star-nosed moles.

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Economic Importance for Humans: Positive

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.

Positive Impacts: controls pest population

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Wikipedia

Star-nosed mole

A specimen from the collection of the Muséum de Toulouse.

The star-nosed mole (Condylura cristata) is a small mole found in wet low areas of eastern Canada and the northeastern United States, with records extending along the Atlantic coast as far as extreme southeastern Georgia.[3] It is the only member of the tribe Condylurini and the genus Condylura.

The star-nosed mole is easily identified by the twenty-two pink fleshy appendages ringing its snout, which is used as a touch organ with more than 25,000 minute sensory receptors, 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.[4]

Description[edit]

The star-nosed mole is covered in thick, blackish-brown, water-repellent fur, and has large, scaled feet and a long, thick tail, which appears to function as a fat storage reserve for the spring breeding season. Adults are 15 to 20 cm (5.9 to 7.9 in) in length, weigh about 55 grams (2 oz), and have 44 teeth. The mole's most distinctive feature is a circle of 22 mobile, pink, fleshy tentacles (called rays) at the end of its snout, from which it derives its name. These are used to identify food by touch, such as worms, insects and crustaceans.

The extremely sensitive star-like structure is covered with minute touch receptors known as Eimer's organs. The nose is about 1 cm in diameter with roughly 25,000 Eimer's organs distributed on 22 appendages.[5] Eimer's organs were first described in the European mole in 1871 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,[6] 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 short as 120 milliseconds (average: 227 ms) to identify and consume individual food items.[7] Its brain decides in the ultra short time of 8 ms if a prey is edible or not. 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.[8]

Ecology and behavior[edit]

The star-nosed mole lives in wet lowland areas and eats small invertebrates, aquatic insects, worms, mollusks, small amphibians and small fish.[9] 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. Little is known about the social behavior of the species, but it is suspected to be colonial.

The star-nosed 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. Their eyes, ears, and star are all sealed, only opening and becoming useful 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, various skunks and mustelids, and large fish, as well as domestic cats.

Snout comparison to visual organ[edit]

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 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".[10]

The star-shaped nose is a unique organ only found 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 8 milliseconds it can decide whether something is edible—in fact, this is one of the fastest responses to a stimulus in the animal kingdom[11] 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.[12]

Anatomy and Physiology[edit]

The star nose is a highly specialized sensory-motor organ shaped by 22 fleshy finger-like appendages, or tendrils, that ring their nostrils and are in constant motion as the mole explores its environment. The star itself is a centimeter across and thus has a diameter slightly smaller than a typical human fingertip.[13] Nevertheless it is much larger than the nose of other mole species, covering 0.92 cm2 (0.14 sq in) per touch compared to 0.11 cm2 (0.02 sq in) covered by the noses of other mole species. This structure is divided into a high resolution central fovea region (the central 11th pair of rays) and less sensitive peripheral areas.[14] In this way the star works as a “tactile eye” where the peripheral rays (1–10 on each side) study the surroundings with erratic saccade-like movements and direct the 11th ray to objects of interest. Just like the primate’s foveating eye.[15]

Regardless of the anatomical position of the star as a distal (protruding or extending) portion of the nose, this is not an olfactory structure nor an extra hand. The appendages do not contain muscles or bones and are not used to manipulate objects or capture prey. They are controlled by tendons by a complex series of muscles that are attached to the skull in order to perform a role that seems to be purely mechanical.[16] For this purpose, the star also contains a remarkably specialized epidermis covered entirely by 25,000 small raised domes or papillae of approximately 30–50 mm (1.2–2.0 in) in diameter.[13] These domes, known as Eimer’s organs, are the only type of receptor organs found in the star of the star-nosed mole which proof that the star-like structure has clearly a mechanical functioning.

Eimer’s organ is a sensory structure also found in nearly all of the approximately 30 species of mole,[17] however neither contain as much as in Condylura.[16] This large amount of specialized receptors makes the star ultrasensitive—about 6 times more sensitive than the human hand, which contains about 17,000 receptors.

Each Eimer’s organ is supplied by a number of primary afferents, thus the star is densely innervated.[16] It is associated with a Merkel cellneurite complex at the base of the cell column, a lamellated corpuscle in the dermis just below the column and a series of free nerve endings that originate from myelinated fibers in the dermis, run through the central column and end in a ring of terminal swellings just below the outer keratinized skin surface.[13] All 25,000 Eimer’s organs distributed along the surface of the star have this basic structure in all 22 appendages. Nevertheless the fovea region (11th pair of rays), which is shorter in area, has a lower density of these organs—900 Eimer's organs on its surface while some of the lateral rays have over 1500. This may sound contradictory with the fact that this region has higher resolution and an important role in foraging behavior. However, instead of having more sensory organs this fovea region uses a different approach in which a skin surface may be more sensitive to mechanoreceptice input; it has more innervation density. Rays 1 through 9 each had about 4 fibers per Eimer's organ, while rays 10 and 11 had significantly higher innervation densities of 5.6 and 7.1 fibers per organ, respectively,[16] revealing how the sensory periphery is differentially specialized across the star.

The myelinated fibers innervating the 11 rays were photographed and counted from an enlarged photomontage by Catania and colleagues. The total number of myelinated fibers for half of the star ranged from 53,050 to 93–94; hence the total fibers for the entire star vary from roughly 106,000 to 117,000. This means that tactile information from the environment is transmitted to the SNC rapidly.[13] This would be insufficient without an adequate processing system, but in the star-nosed mole, the processing also occurs at a very high speed almost approaching the upper limit at which nervous systems are capable of functioning. The threshold at which the mole can decide whether or not something is edible is of 25 milliseconds: 12 milliseconds to the neurons in the mole’s somatosensory cortex to respond to touch and other 5 milliseconds for motor commands to be conducted back to the star.[18] In comparison, this whole process takes 600 milliseconds in humans.

The importance of the star-like nose in the mole’s lifestyle is evidenced in the somatosensory representation of the nose. Electrophysiological experiments which consist on electrodes placed on the cortex during gently stimulation of the body demonstrated that roughly 52% of the cortex is devoted to the nose. This means that more than half of the brain is dedicated to processing sensory information acquired by this organ, even when the nose itself is only roughly the 10% of the mole’s actual size. Thus, it may be concluded that the nose substitutes for the eyes, with the information from it being processed so as to produce a tactile map of the environment under the mole’s nose. As other mammals, the somatosensory cortex of the star-nosed mole is somatotopically organized such that sensory information from adjacent parts of the nose is processed in adjacent regions of the somatosensory cortex. Therefore the rays are also represented in the brain. The inferior most sensitive pair of rays (11th) had a larger representation on the somatosensory cortex, even when these are the shortest pair of appendages in the nose of the star-nosed mole.

Other important fact of the representation of the star in the cerebral cortex is that each hemisphere had clearly visible set of 11 stripes representing the contralateral star. In some favorable cases, a smaller third set of stripes was also apparent; opposite to other body structures that have a unique representation, with each half of the body represented in the opposite cerebral hemisphere.[13] Thus, opposite to other species, the somatosensory representation of the tactile fovea is not correlated with anatomical parameters but rather is highly correlated with patterns of behavior.[13][18] Recordings from active neurons in the somatosensory cortex show that most cells (97%) responded to light tactile stimulation with a mean latency of 11.6 milliseconds. Besides a fairly large proportion of these neurons (41%) were inhibited by stimulation of proximate Eimer’s organs outside their excitatory receptive field. Consequently the ability of the star to rapidly determine location and identity of objects is enhanced by small receptive fields and its associated collateral inhibition system that constrains cortical neurons with short latency responses.[13]

Sensitivity to the Mechanical Stimuli[edit]

In 1996 Marasco determined that the threshold by which the star-like structure senses the mechanical stimuli depends on which type of the Eimer’s organ was excited. He characterized three main classes of Eimer’s receptors, including one of slow adaptation (Tonic receptor) and two of rapid adaptation (Phasic receptor). The tonic receptor has a response similar to that of a Merkel cell-neurite complex. It has free terminals and is therefore able to detect pressure and texture with a high sensitivity and at a Random Sustained Discharge. The rapid adapting responses include a Paccinian-like response based on an (on-off) response caused by pressure and mechanical vibrations with maximum sensitivity to stimuli at a frequency of 250 Hz. The differences between both rapid responses rely on the fact that one of them only has a response during the compression phase.[13][19]

Frequency Sensitivity[edit]

Among the receptors described, Marasco identified that there were receptors relatively unresponsive to compressive stimuli but were acutely responsive to any kind of stimulus that brushed or slid across the surface of the nose (Stimuli applied with large displacements and high velocity). In contrast, there were other receptors which responded robustly to small magnitude compression of any kind but were not responsive to sweeping stimuli. The receptors that were sensitive to sweeping were maximally activated across a broad range of frequencies from 5-150 Hz at large displacements ranging from 85–485 μm. Conversely, the receptors that respond to compressive stimuli showed a narrow peak of maximal activity at 250–300 Hz with displacements from 10–28 μm.

Directional Sensitivity[edit]

Based on the circular organization of the nerve endings and its innervation pattern in Eimer’s organs, Marasco proposed by mapping experiments that nearly all receptors in the star-nosed mole have a preference for a particular direction of applied stimuli.[19] Thus, while one receptor elicits a strong response if compressed in one direction, it may stay “silent” when compressed in another one.

Velocity Sensitivity[edit]

Examination of the threshold of velocity at which the receptors responded identified that the minimum velocity of cell response was 46 mm/s, corresponding to the approximate speed of the nose during foraging behavior.[19]

Transduction of the Mechanical Signal[edit]

Taking into account that Eimer’s organ senses mechanical deformation, its mechanism of transduction can be explained in a few steps:

  1. Stimuli cause depolarization of the receptor membrane, resulting in a receptor potential and therefore a current towards the node of Ranvier.
  2. If the receptor potential in maintained and the generated current is enough to reach the node of Ranvier, then the threshold is reached to produce an action potential.
  3. When the action potential is produced, ionic channels are activated so that the mechanical impulse is transduced into electrical.
  4. This signal is carried along the axon until it reaches the SNC where the information is processed.

Although these summarized steps of mechanical transduction give a hint of how the star-nosed mole converts mechanical information into potential actions, the entire mechanism of transduction behind this intricate mechanoreceptor is still unknown and further studies are required.

Behavior[edit]

Despite the poorly developed eyes, star-nosed moles have an intricate system to detect prey and understand their environment.[20] During exploration, the mole's star-like appendage produces brief touches which compress Eimer’s organ against objects or substrate.[13] When foraging, moles search in random patterns of touches lasting 20–30 ms. Catania and colleagues demonstrated that the tactile organ of the star-nosed mole is preferentially innervated by putative light touch fibers. When the outer appendages of the star come into slight contact with a potential food source, the nose is quickly shifted so that one or more touches are made with the fovea (the two lower appendages; 11th pair) in order to explore objects of interest in more detail - especially potential prey.[21] This foraging behavior is exceptionally fast, such that the mole may touch between 10 and 15 separate areas of the ground every second. It can locate and consume 8 separate prey items in less than 2 seconds and begin searching again for more prey in as little as 120 ms, although the average time is 227 ms.

The sequence described constitutes handling time. In studies made by high-speed video, the mole always foveated to the 11th appendage to explore a food item.[15] The use of the 11th appendage of the tactile fovea is surprisingly similar to the manner in which human eyes explore details of a visual scene.[13]

This star-like nose also enables the mole to smell underwater, something which was previously thought impossible in mammals, which require the inspiration of air during olfaction to convey odorants to the olfactory epithelium.[22] Although the star-like structure is not a chemoreceptor itself, it helps the star-nosed mole to blow between 8 to 12 small air bubbles per second, each 0.06 to 0.1 mm in size, onto objects or scent trails. These bubbles are then drawn back into the nostrils, so that odorant molecules in the air bubbles are wafted over the olfactory receptors.[23]

In 1993, Gould and colleagues proposed that the star-like proboscis had electroreceptors and that the mole was therefore able to sense the electrical field of its prey[24] prior to mechanical inspection by its appendages. Through behavioral experiments, they demonstrated that moles preferred an artificial worm with the simulated electrical field of a live earthworm to an identical arrangement without the electrical field. They suggested, therefore, that the nerve endings in the star’s tentacles are indeed electroreceptors and that the moles move them around constantly to sample the strength of the electromagnetic field at different locations as they search for prey.[20][24] However, the theory remains unexplained physiologically and has not yet been accepted by the scientific community. Instead, the theory proposed by Kenneth Catania, in which the function of the appendage is purely tactile, seems to be more feasible and is the one currently accepted.

Evolution[edit]

The development of the star-like appendages suggests precursors with proto-appendages on an ancestor's snout which became elevated over successive generations.[25] Although this theory lacks fossil evidence or supporting comparative data, nearly all extant moles have sheets of the Eimer’s organ making up the epidermis of their snout around the nares. Also, recent studies of Catania and colleagues identified one North American species (Scapanus townsendi) with a set of proto-appendages extending caudally on the snout which exhibit a striking resemblance to the embryonic stages of the star-nosed mole, [25] although Scapanus townsendii has only eight subdivisions on its face rather than the 22 appendages found on the star-nosed mole. Such change is of common occurrence in evolution and is explained by the advantage of efficiently adding modules to the body plan without need to reinvent the regulatory elements which produce each module. Thus, although the star is unique in its shape and size, it seems feasible that the structure is based on a more ancestral bauplan as it comprises similarities found in a wide range of other moles and also in the molecular structure of other mammals.[25]

The picture which emerges suggests that the star-nosed mole is an extreme in mammalian evolution, having perhaps the most sensitive mechanosensory system to be found amongst the mammals.[13] The evolutionary process which led to elaboration of this star-like nose is based on two theories. One proposes the development of the structure of the star as a consequence of the selective pressure of the star-nosed mole's wetland habitat. Wetlands have a dense population of small insects, so exploiting this resource requires a higher resolution sensory surface than that of other moles. Thus, a shift to the wetland environment may have provided a selective advantage for a more elaborate sensory structure. Furthermore, in wild caught moles of many species, the Eimer’s organs show obvious signs of wear and abrasion.[17] It appears that constant and repeated contact with the soil damages the sensory organs, which have a thin keratinized epidermis. Star-nosed moles are the only species which live in the moist, muddy soil of wetlands where the less abrasive environment has allowed the delicate star-shaped structure to evolve.[13]

The second theory, that of prey profitability, explains the foraging speed of the star-nosed mole. Prey profitability, (i.e. energy gained divided by prey handling time), is an essential variable for estimating the optimal diet. When handling time approaches zero, profitability increases dramatically.[25] Due to the small invertebrate prey available in the wetlands, the star-nosed mole has developed handling times as short as 120ms. The dazzling speed with which it forages therefore counterbalances the low nutritional value of each individual piece of food and maximizes the time available for finding more. Further, the proximity of the star-shaped nose to the mouth greatly reduces the handling time required before food can be ingested and is a major factor in how the star-nosed mole can find and eat food so quickly.[13][25]

Current Applications in Engineering[edit]

The study of highly specialized systems often allows better insight into more generalized ones. The mole's striking, star-like structure may reflect a general trend in its “less remarkable” relatives, including humans. Little is known today about the molecular mechanisms of tactile transduction in mammals. As the drosophila fly is to genetics, or the squid giant axon, is to neurobiology,[13] the star-nosed mole may be the model organism for tactile transduction. The proper understanding of its saccade-like system and associated transduction may lead in future to the development of new types of neural prosthesis. Furthermore, the outstanding speed and precision at which the mole performs may provide insights into the structural design of intelligent machines as an artificial response to the remarkable sensory ability of the star-nosed mole.

Snout as related to optimal foraging theory[edit]

According to optimal foraging theory, organisms forage in such a way as to maximize their net energy intake per unit time. In other words, they behave in such a way as to find, capture and consume food containing the most calories while expending the least amount of time possible in doing so. With extremely short handling times for eating very small prey, star-nosed moles can profitably consume foods that are not worth the time or effort of slower animals, and having a food category to themselves is a big advantage. Furthermore, just behind the 11th ray of the star, the star-nosed mole has modified front teeth that form the equivalent of a pair of tweezers. High-speed video shows these specialized teeth are used to pluck tiny prey from the ground. Neuroscientist Kenneth Catania reports, "It is also clear from the behavior that the teeth and the star act as an integrated unit — the 11th rays, located directly in front on the teeth, spread apart as the teeth move forward to grasp small food. Thus, tweezer-like teeth and the exquisitely sensitive star likely evolved together as a means to better find and handle small prey quickly...it appears that the ability to rapidly detect and consume small prey was the major selective advantage that drove the evolution of the star."[10]

References[edit]

  1. ^ Hutterer, R. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 300–301. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  2. ^ Hammerson, G. (2008). "Condylura cristata". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. Retrieved 9 February 2010. 
  3. ^ Feldhamer, George A.; Thompson, Bruce C.; Chapman, Joseph A., eds. (2003). Wild Mammals of North America: Biology, Management and Conservation (2nd ed.). Baltimore, Maryland: Johns Hopkins University Press. 
  4. ^ Catania, Kenneth C. (June 2000). "A Star is Born". Natural History Magazine. Retrieved March 2010. 
  5. ^ Catania, K.C. (1999). "A nose that looks like a hand and acts like an eye: the unusual mechanosensory system of the star-nosed mole". Journal of Comparative Physiology A 185 (4): 367–372. doi:10.1007/s003590050396. PMID 10555270. 
  6. ^ Gould, Edwin; McShea, William; Grand, Theodore (1993). "Function of the Star in the Star-Nosed Mole, Condylura cristata". Journal of Mammalogy (American Society of Mammalogists) 74 (1): 108–116. doi:10.2307/1381909. JSTOR 1381909. 
  7. ^ Catania, Kenneth C.; Remple, Fiona E. (2005). "Asymptotic prey profitability drives star-nosed moles to the foraging speed limit". Nature 433 (7025): 519–522. doi:10.1038/nature03250. PMID 15690041. 
  8. ^ Catania, K.C. (21 December 2006). "Olfaction: Underwater 'sniffing' by semi-aquatic mammals". Nature 444 (7122): 1024–1025. doi:10.1038/4441024a. PMID 17183311. 
  9. ^ State University of New York, College of Environmental Science and Forestry. Adirondack Ecological Center: Star-nosed Mole. Retrieved 2012-07-20.
  10. ^ a b Kenneth C. Catania (1 September 2012). "A Nose for Touch". TheScientist. Retrieved 21 February 2014. 
  11. ^ "BBC Nature – Tactile sense videos, news and facts". BBC. BBC Nature. 1970-01-01. Retrieved 2014-02-20. 
  12. ^ Album Jet (2013)
  13. ^ a b c d e f g h i j k l m n Catania, Kenneth C. (2011). "The sense of touch in the star-nosed mole: from mechanoreceptors to the brain". Phil Trans R Soc B 366: 3016–3025. doi:10.1098/rstb.2011.0128. 
  14. ^ Catania, Kenneth C. (2012). "Tactile sensing in specialized predators – from behavior to the brain". Current Opinion in Neurobiology (Elsevier) 22: 251–258. doi:10.1016/j.conb.2011.11.014. 
  15. ^ a b Catania, Kenneth C.; Remple, Fiona E. (2004). "Tactile foveation in the star-nosed mole". Brain Behav Evol 63 (1): 1–12. doi:10.1159/000073755. PMID 14673194. 
  16. ^ a b c d Catania, Kenneth C. (1999). "A nose that looks like a hand and acts like an eye: the unusual mechanosensory system of the star-nosed mole". J Comp Physiol A 185 (4): 367–72. doi:10.1007/s003590050396. PMID 10555270. 
  17. ^ a b Catania, Kenneth C. (2000). "Mechanosensory organs of moles, shrew-moles, and desmans: a survey of the family Talpidae with comments on the function and evolution of Eimer’s organ". Brain Behav Evol 56: 146–174. doi:10.1159/000047201. 
  18. ^ a b Catania, Kenneth C.; Kaas, Jon H. (1997). "Somatosensory Fovea in the Star-Nosed Mole: Behavioral Use of the Star in Relation to Innervation Patterns and Cortical Representation". The Journal of Comparative Biology 387 (2): 215–233. doi:10.1002/(SICI)1096-9861(19971020)387:2<215::AID-CNE4>3.0.CO;2-3. PMID 9336224. 
  19. ^ a b c Marasco, Paul D (2006). The structure and Function of Eimer’s Organ in the Mole. Dissertation Submitted to the faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY.
  20. ^ a b Zimmer, Carl. (1993) The Electric Mole. Available online: http://discovermagazine.com/1993/aug/theelectricmole261#.Up-E3tIz2Fk
  21. ^ Catania Kenneth, C. Remple Fiona, E. (2005) Asymptotic prey profitability drives star-nosed moles to the foraging speed limit. Nature Publishing Group. Letters to Nature. 519–522
  22. ^ Howell, A. B. (1930) Aquatic Mammals: Their Adaptations to Life in the Water. Springfield, Illinois.
  23. ^ Catania Kenneth, C. (2006) Underwater ‘sniffing’ by semi-aquatic mammals. Nature Publishing Group. Brief communications. 1024–1250
  24. ^ a b Gould, Edwin; McShea, William; GrandSource, Theodore (1993). "Function of the Star in the Star-Nosed Mole, Condylura cristata". Journal of Mammalogy 74 (1): 108–116. doi:10.2307/1381909. 
  25. ^ a b c d e Catania, Kenneth C.; Northcutt, R. Glenn; Kaas, Jon H. (1999). "The development of a biological novelty: A different way to make appendages as revealed in the snout of the star-nosed mole Condylura cristata". The Journal of Experimental Biology 202 (Pt 20): 2719–2726. PMID 10504308.  open access publication - free to read (Free full text available for further reading)
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