No one can watch these pretty little creatures without being interested and amused. But amusement ought not to be our sole object in observing the inhabitants of a brook. Let us catch one of the animals and keep it long enough to examine it. There is little difficulty in capturing a water-shrew, as the little animals are so fearless when they think themselves unobserved that a small hand-net can easily be slipped over them in their gambols. We need not keep our captive long, and, after inspecting the characteristic fringe of the feet and tail, we will examine its head and jaws.
A mere glance at the head ought to tell us that it cannot be a mouse, no mouse having a long, pointed snout, which projects far beyond the lower jaw. On opening its mouth and examining its teeth, we not only see that it cannot be a mouse, but that it is not even a rodent. It is, in fact, much more nearly related to the hedgehog than to the mouse. All its teeth are sharply pointed, and the lower incisors project almost horizontally forwards. The animal must, therefore, be predacious in character, and a comparison with the structure of other animals shows that it belongs to the important though not very numerous group of the insectivora, or insect-eaters, of which the mole is the generally accepted type. There are, however, some systematic zoologists who hold that the shrews, and not the moles, ought to be the typical representatives of the insectivora. This, however, is a matter of opinion, and its discussion does not come within the scope of our present undertaking.
Before we release our captive, we will examine its ears.
These are small, as are those of all water-inhabiting mammals, but there is a peculiarity in their structure which is worthy of notice. They are furnished with three small valves, which, being made on the same principle as those of the heart, are closed by the pressure of the water as soon as the animal dives below the surface, and open by their own elasticity when it emerges.
Now, we will allow it to escape into the water, and take note of it as it swims away.
I have already casually referred to the irregular course which it pursues in swimming. This is due to the fact that the water-shrew drives itself along by alternate strokes with the fringed hind feet, so that its progress reminds the observer of that of a boat propelled by two unskilful rowers, who have not learned to keep time. Still, its pace is tolerably rapid, though it lacks the steady directness which characterises that of the water-vole.
Another remarkable point in its swimming is that the outstretched legs cause the skin of the flanks to be widened and flattened in a way that reminds the observer of the flying squirrel when passing through the air. Although in the water-shrew the skin is not nearly as much flattened as in the squirrel, it is expanded sufficiently to alter the shape of the creature in a notable manner.
Supposing the observer to be tolerably familiar with the terrestrial shrews, he must have been struck by the blackness of the fur of the back, and the contrasting whiteness of the under-surface. So strongly, indeed, is the contrast marked, that an exceptionally dark variety was long considered as a distinct species, and called the “oared shrew.”
Like the insectivora in general, the water-shrew is not at all particular in its diet, providing it be of an animal nature. As most of us know, the hedgehog, although its normal food consists of insects, snails, and the like, will feed on frogs, toads, mice, and even snakes and blindworms. So will the water-shrew, if it can be fortunate enough to find the dead bodies of any of these creatures, for it is not sufficiently powerful to kill them for itself.
In Mr. Bell’s work, to which reference has already been made, there is an interesting notice of the carnivorous habits of the water-shrew.