Еуразия су сормусының сипаттамасы

Species of mammal

The Eurasian water shrew (Neomys fodiens), known in the United Kingdom as the water shrew, is a relatively large shrew, up to long, with a tail up to three quarters as long again. It has short, dark fur, often with a few white tufts, a white belly, and a few stiff hairs around the feet and tail. It lives close to fresh water, hunting aquatic prey in the water and nearby. Its fur traps bubbles of air in the water which greatly aids its buoyancy, but requires it to anchor itself to remain underwater for more than the briefest of dives. Like many shrews, the water shrew has venomous saliva, making it one of the few venomous mammals, although it is not able to puncture the skin of large animals, nor that of humans. Highly territorial, it lives a solitary life and is found throughout the northern part of Europe and Asia, from Britain to Korea.

The Eurasian water shrew grows to a length of about long with a tail length of and weight of The dense short fur on the head, back and sides is greyish black. The underparts are dirty white and are sharply demarcated from the dorsal surface. Sometimes they are tinged with rusty brown or occasionally are entirely dark grey. There is a white spot just behind the eye and often another near the small, rounded ear which is nearly hidden in the fur. The nose is black and the snout long and tapering. The sharp, mostly white teeth are tipped with red, typical of the shrew subfamily Soricinae. The rusty colour comes from deposits of iron which serve to harden the enamel and which are concentrated in the tips of the teeth, particularly the molars which are the teeth most subject to wear. The female has five pairs of nipples. The legs are short and the hind feet are powerful, with a fringe of short, stiff hairs on the outer edge, both of which features assist while it is driving its body through the water. The tail is slender and has a keel of short white hairs on the underside. It rarely strays far from water and is found in and around ditches, streams, ponds, watercress beds, fish ponds, damp meadows and rough bushy ground adjoining water. On the whole they are solitary animals that seem to mutually avoid each other and there is no social hierarchy. The Eurasian water shrew has a pair of glands under its jaw which produce venom, and this has been shown to be potent against the field vole (Microtus agrestis), and lethal at a minimum dose of fifteen milligrams per kilogram body weight. The venom consists of a paralytic peptide which has been patented for use in neuromuscular therapy. Overall, the Eurasian water shrew venom has stronger paralytic properties and lower cardioinhibitory activity. Thus acting as an immobilizing agent towards their prey or to organisms that may threathen them. Their behavior in captivity is described in Konrad Lorenz's book King Solomon's Ring.

The International Union for Conservation of Nature lists the Eurasian water shrew as being of "Least concern" in its Red List of Threatened Species. This is because it has a large population distributed across a wide range and its population seems fairly stable. In some areas habitat degradation is occurring and wetlands are being drained but not to such an extent as to increase the status to "Vulnerable". Other possible threats include agricultural products and sewage which may pollute waterways and reduce the availability of food. In western Spain, a separate subspecies (N. f. niethammeri) has a very limited range and may be declining in numbers.