It's about the size of a tennis ball, and it weighs no more than a tennis ball, and it reacts a bit like a tennis ball when submerged in water. But it's not a tennis ball, of course. It's an elusive little mammal called the Water Shrew.
Dark except for its silvery belly, the Water Shrew boasts water-resistant fur that traps air bubbles when the animal dives in pursuit of prey. Once the shrew stops swimming, these air bubbles then catapult it back to the surface -- an action not unlike what happens when a tennis ball is pushed underwater and released.
The Water Shrew also possesses wide hind feet that are fringed with stiff hairs. This combination helps the shrew swim. The shrew can walk on water, too. Or at least run across the water's surface for several feet. Set a tennis ball on the water, and it just sits there.
Click here to learn more about the Water Shrew.