Eurasian Water Shrew

Fascinating facts about the Eurasian Water Shrew

• A Eurasian water shrew injects venom into its prey — one of the few venomous mammals on Earth. The shrew's saliva contains a neurotoxin that paralyses small fish and insect larvae, allowing a creature weighing just 12 grams to wrestle prey much larger than itself. This venom was so recently discovered (1999) that it rewrote what we thought mammals could do.
• Water shrews run across water like tiny, furry Jesus Christ lizards. Their hind feet are fringed with stiff hairs that trap air bubbles, letting them skitter across pond surfaces at 150 centimetres per second before diving. They can hold their breath for 40 seconds and hunt by touch alone in total darkness on the riverbed.
• The shrew's heart beats 1,200 times per minute — so fast that time almost seems to move at a different speed inside its body. To fuel this furnace, it must eat nearly half its own body weight in food every single day, hunting almost constantly through the night. Stop eating for six hours and a water shrew dies.
• Despite being smaller than your thumb, a water shrew can catch and kill a 20-centimetre trout — a fish 40 times heavier than itself. It anchors itself with its claws and uses its venomous bite to immobilise the fish before dragging it to a burrow to eat. Pound for pound, few predators hunt with such brutality.
• Eurasian water shrews navigate their pitch-black riverbed world using echolocation clicks — a skill they share with bats and whales but that scientists have barely studied. Each click bounces off pebbles and prey, painting a sonic map in their brain. They hunt the same 50-metre stretch of stream every night, memorising every rock, and will reuse the same underwater tunnels for years.

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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