Eurasian Water Shrew

Fascinating facts about the Eurasian Water Shrew

• It can stay submerged for twenty seconds, then must surface for air, yet its fur traps a layer of air that makes it unusually buoyant. This air layer forces the shrew to launch itself into the water to dive, that lets it hunt aquatic prey while staying dry underneath. The buoyancy also means any water on its coat is quickly soaked up by the burrow walls, keeping it ready for the next plunge.
• Its saliva contains a neurotoxic venom that can kill a field vole at just fifteen milligrams per kilogram, making it one of the few venomous mammals. The venom is delivered through grooves in its hooked incisors, allowing the shrew to immobilise prey larger than itself and meet its high metabolic demands. This chemical weapon turns tiny bites into lethal strikes, expanding its diet to include small fish and amphibians.
• It can sprint up to three kilometres on land while foraging, a distance far beyond its modest 500-square-metre home range. This extensive travel lets it exploit both aquatic and terrestrial invertebrates, from snails in streams to beetles in nearby meadows.
• Females can produce up to two litters a year, each containing four to eight young, after a gestation of just twenty-four days. The pups open their eyes at fifteen to eighteen days, are weaned by four weeks, and leave the nest after about forty days, reaching sexual maturity at six to eight months. This rapid life cycle helps sustain populations despite a wild lifespan of only three years.
• Its karyotype of 2n = 52 and FN = 98, reflecting an ancient split that predates the divergence of its sister species. Genetic and morphological data suggest this split was driven by Pleistocene climate swings, pushing the shrew south during cold spells and north again when it warmed.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia

At a glance

About the Eurasian Water Shrew

In the shadowy realm of rivers and streams, the Eurasian Water Shrew darts with frenetic urgency, its sleek, dark form slicing through the water with barely a ripple, as it pursues the tiny crustaceans and insects that sustain it. With its dense, velvety fur and remarkable ability to dive and forage underwater, this tiny, fearless hunter is a marvel of adaptation, capable of thriving in some of Europe's most fast-flowing and inhospitable aquatic environments. As it swims and forages, its large, bead-like eyes gleam with an unyielding intensity, a testament to its status as one of the continent's most resilient and fascinating small mammals.

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