Animal Diversity Web

Ge­o­graphic Range

Neomys fo­di­ens oc­curs through­out Eura­sia, to west­ern Siberia, north­ern Asia Minor, the Pa­cific coast of Siberia, and North Korea.

• Biogeographic Regions
• palearctic
  • native

Habi­tat

Found on the banks of both stand­ing or flow­ing fresh water and ad­ja­cent areas.

• Terrestrial Biomes
• forest

• Aquatic Biomes
• lakes and ponds
• rivers and streams

Phys­i­cal De­scrip­tion

A darkly col­ored shrew with a white un­der­side. Col­oration on dor­sal and ven­tral sides are sharply de­mar­cated. A fringe of bris­tles runs along the ven­tral sur­face of the tail and on the paws which are thought to serve as a swim­ming aid. Teeth have red tips. Fe­males have five pairs of mam­mae.

• Other Physical Features
• endothermic
• bilateral symmetry

• Average mass

  15 g

  0.53 oz

  AnAge

• Average basal metabolic rate

  0.328 W

  AnAge

Re­pro­duc­tion

The breed­ing sea­son in Eng­land oc­curs fom April to Sep­tem­ber, with mul­ti­ple lit­ters per sea­son. Lit­ter size can be be­tween 3 and 12, more com­monly 5 or 6. Ges­ta­tion lasts ap­prox­i­mately 20 days, and lac­ta­tion twice that. Sex­ual ma­tu­rity is reached be­tween 6 and 8 months.

• Key Reproductive Features
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual

• Average number of offspring

  5

  AnAge

• Average gestation period

  20 days

  AnAge

• Average age at sexual or reproductive maturity (female)
  Sex: female

  106 days

  AnAge

• Average age at sexual or reproductive maturity (male)
  Sex: male

  106 days

  AnAge

Lifes­pan/Longevity

• Average lifespan
  Status: wild

  3.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: captivity

  1.6 years

  Max Planck Institute for Demographic Research

Be­hav­ior

These shrew are soli­tary. If kept in cap­tiv­ity, in­di­vid­u­als are both ter­ri­to­r­ial and ag­gres­sive to­ward one an­other. They are gen­er­ally ac­tive both at night and dur­ing the day, and they do not hi­ber­nate through the win­ter. One lab­o­ra­tory study found that shrews of this species mu­tu­ally avoid one an­other much of the time, but when this does not work ac­tive an­tag­o­nism can occur. They also seem to have no typ­i­cal so­cial hi­er­ar­chy.

• Key Behaviors
• motile

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• tactile
• chemical

Food Habits

These shrews for­age al­most ex­clu­sively un­der­wa­ter, ef­fi­ciently prey­ing on aquatic in­ver­te­brates such as snails, mol­lusks, fresh­wa­ter in­sects, and also small ver­te­brates such as fish, am­phib­ians and frogs. Prey are weak­ened by a poi­so­nous se­cre­tion from the sub­max­il­lary gland. They gen­er­ally for­age by tak­ing a dive that can last up to 20 sec­onds. After com­ing onto land, water shrews quickly run into their bur­rows and emerge a mo­ment later al­most dry, after com­ing through the tight squeeze of the tun­nel where the water is ab­sorbed by the soil. The process is then re­peated a few me­ters away along the stream bank. Water shrews are also known to eat some ter­res­trial in­sects as well, such as dipteran lar­vae.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

These shrews eat the lar­vae of in­sects which some hu­mans find both­er­some.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

No neg­a­tive im­pacts known.

Con­ser­va­tion Sta­tus

Quite com­mon within its ge­o­graph­i­cal range.

• IUCN Red List

  Least Concern
  More information

Other Com­ments

Dur­ing dives, air re­mains trapped be­tween the outer hairs of the thick coat of water shrews. This greatly in­creases the bouyancy of this shrew. In a lab­o­ra­tory ex­per­i­ment, a few tenths of a mg of the neu­ro­toxic saliva killed a vole very quickly.

Con­trib­u­tors

Brid­get Fahey (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Nowak, R.M. Walker's Mam­mals of the World, 5th Edi­tion. Johns Hop­kins Uni­ver­sity Press.

Grize­mek's En­cy­clo­pe­dia of Mam­mals. Mc­Graw-Hill Pub­lish­ing Co.