NATURE-STUDY AT THE SEASIDE
Introduction
Many very curious and interesting creatures are to be found on the seashore, and we dare say you would like to know something about them. So let us take, in thought, four rambles along the shore together. First we will go for a stroll on the sandy beach, which is left quite dry for some little time when the tide goes down. Next, we will pay a visit to the stretches of mud just above low-tide mark, left bare in the coves for perhaps a couple of hours twice each day. For our third ramble we will wander about among the rocks, and examine the creatures which are crawling about on them, or burrowing into them, or hiding underneath the great masses of seaweed with which they are covered. And then, lastly, we will search in the pools which lie between the rocks, where we shall probably find some of the most interesting animals of all.
We will suppose that these walks are on our Atlantic coast, for we have not time now to explore the shores of the Pacific and describe its animals, many of which are very different from those of the Eastern coast.
I
ALONG THE SANDY BEACH
As all the coast of the United States south of New York, and Cape Cod and Long Island besides, are formed of soil and pebbles ground off the tops and sides of the Appalachian ranges of mountains, the ocean beaches and the bottom of the sea near shore are all of sand, constantly swept by currents, and moved by storms. On such a plain of shifting sand not many plants or animals can live save those which are able to swim or to bury themselves; and not nearly so long a list can be made as among the rocks which give root-hold and shelter, or where the bottom is muddy, as we shall see later; yet a walk will enable us to find a good many things about which you ought to know something.
Here, for instance, are a lot of shells, the hard outer coats of the soft boneless creatures we call mollusks, such as you know very well on land as snails. When you have filled your little basket, if we asked you to sort them into two kinds, you would be almost sure to put those which consist of two pieces, attached together, into one pile, and those which are in one solid piece, and more or less twisted like a snail, into the other. This would mark a real division, for the first heap would have the clam-like mollusks which we call bivalves, and the second would have those coiled gastropod mollusks that we may call sea-snails.
The bivalves scattered along the beach are all dead and mostly broken, for they have been washed up from muddy places; but many of the sea-snails may be found alive and belong here on the sand, and so we may look first at them.
Here is a big one to begin with which the southern fishermen call a conch and the northern oystermen a winkle. It is shaped like a pear, and pushing out of its shell a very tough muscular part of its body called the foot, it plows along in the sand, or even burrows into it, small end first, searching for food, which consists of animal matter, either dead or alive. It finds this by its sense of smell, and when it comes to it, thrusts out of its head, near the forward end of the foot, a long ribbon-like tongue, covered with hundreds of minute flinty teeth, and rasps away the flesh. Winkles are numerous everywhere and are of great service in devouring dead fish, etc., which would pollute the water; but they also eat a great quantity of oysters, as we shall see presently. You will find two kinds, and should note how their shells differ.
Very likely you will find among the long rows of dead eel-grass and drift-stuff marking the reach of high tides a twisted string of most curious objects, each about as big as a cent, feeling as if made of yellow paper and strung together like a necklace on a stiff cord. These are the eggs of a conch, or more truly, the egg-cases, for in each cent-like capsule was placed an egg. You can prove it by opening some of them. In the dry ones you will probably find only dead young shells, hardly bigger than pin-heads, which have hatched from the eggs; but now and then you may pick up a soft and elastic set, and in these, which are alive, or have only lately been torn from the weeds in deep water and thrown upon the beach, you will find much larger baby conchs, which by and by would have found a way out and begun to travel about.