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.
We have already picked up several different sorts of slender, twisted sea-snails of small size, and a few as big as a walnut and almost as round, save for the circular opening out of which the animal pushes its foot. His name is Natica, and he is one of the worst foes of the clam, whose shell he bores. Here, half buried in the wet sand at the edge of the gentle surf, is a living one, and we can see the grooved trail behind him showing where he has traveled. We will pick him up, and see how hastily he shrinks back into the armor of his shell, and shuts his door with a plate growing upon the tip-end of his foot. All these sea-snails have such a plate, sometimes thin and horny like this one, sometimes thick and shell-like; and if you try to pry it away you will have to tear it to pieces, for the frightened animal will not let go its strong hold. He knows better than to open his door and let you pick him out. Even if you did you would have to tear his body out piecemeal, for he would by no means uncoil it from around the central post of his house and let himself be dragged out whole. This door is a good protection, then, against the claws of crabs and the nibbling teeth of fishes and various small parasites which would like to get at him. It is called an operculum.
Just lift up some of that seaweed and stuff which the waves have piled up. Why, the sand underneath it is simply alive with sandhoppers, besides various jumping and crawling insects, sand-bugs, spiders, etc. But the sandhoppers are most numerous—there must be a hundred, all skipping about so actively that it is quite difficult to follow their movements. They were feeding upon the seaweed, and their sharp little jaws are so powerful that if you were to tie up a few sandhoppers in your handkerchief and carry them home, you would be almost sure to find that they had nibbled a number of little holes in it by the time that you got there! But surely such little creatures as sandhoppers cannot do very much good, even by eating decaying seaweed. Ah! but there are so many of them! Wherever the shore is sandy they live in thousands, and even in millions. If you walk along the edge of the sea, sometimes, when the tide is rising, you will see them skipping about in such vast numbers that the air looks as if it were filled with a kind of mist for a foot or eighteen inches from the ground. And though many of the shore-birds feed upon them, and some of the land-birds do so, too, and the shore-crabs eat a very great many, yet their numbers never seem to grow less.
These sandhoppers are small cousins of the crabs with which we shall get acquainted when we go to the mud-flat; and a search would find many others, such as beach-fleas of various kinds. Here and there are strange grooves, and—look! one of them is growing longer under our very eyes. Dig away the sand just ahead of it, and see what you can find. There it is—a small ivory-like creature, about twice as big as a pumpkin-seed. It is a sand-bug, or hippa, and it burrows along just under the surface, searching for minute particles of food among the grains and letting the sand fall in behind it, for it does not mean to make a tunnel.
One of the waste objects you tossed aside was a piece of wood which the waves have flung up, and which no doubt once formed part of a wrecked vessel.
"And I don't wonder!" some one exclaims, "if all the timbers were as rotten as that!"
The bit of timber is certainly ruined—but what has happened to it? It is full of long round burrows, each about big enough to admit a lead-pencil, and so close together that the walls between them are very little thicker than paper; and every burrow seems to be lined with a kind of glaze.
That is the work of a curious creature known the world over as the ship-worm, which often does a great deal of mischief by burrowing into the hulls of ships and the timbers supporting wharfs and harbor-side buildings. It has a soft round body no bigger than a piece of stout string, and often nearly a foot in length. But it is really a shell-bearing mollusk, like the cockle and the clam. And if you were to look closely at the fore end of its body you would see its bivalve shells, although they are so very small that they might easily be mistaken for jaws.
When first this animal hatches from the egg it is not in the least like its parents. It is just a little round-bodied creature covered almost all over with hairs, by waving which up and down it manages to swim about in the water. But it does not keep its shape very long, for if you were to look at it about thirty-six hours later you would find that it was oval instead of round. Twenty-four hours later still it would be almost triangular, while next day it would be almost round again. And so it would go on changing its form day after day, till at last it fastened itself down by its fleshy foot to a piece of sunken timber and began to burrow in it. And then at last it would take the form of its parents. The birth and growth of most of the bivalves is similar to this; and it must be remembered that these changing larval forms are hardly large enough to see.
Another timber-destroyer all along the New England coast is the gribble, a crustacean related to the sandhoppers, which is not bigger than a grain of wheat, and looks like a pill-bug. It devours wood wherever it finds it under water, and will gradually honeycomb and weaken until they fall to pieces the bases of piles, boat-stairs, and other timbers under water which are not sheathed with copper or filled with creosote. Therefore it is much hated.
A sandy beach is not the place for crabs in general, but there is one kind which we ought to find here. There is one now, but one might wager something that you can't discover it in its hiding-place unless shown to you. Do you see those two little round objects on short stems sticking half an inch out of the sand by that old winkle-shell? Yes? Well, please go and get one or both of them. What! is it alive? some sort of crab, buried in the sand? All right—pick it up, but look out it doesn't nip you! Those claws are powerful, for with them the crabs must seize and firmly hold struggling, slippery fish and other animals, until it can subdue and eat them. Notice how the hind legs are flattened into strong paddles to enable it to swim swiftly upon its prey. In spite of these fierce qualities we call this one a lady-crab, because of its richly ornamented costume—greenish yellow profusely marked with purple rings. It spends most of its time crawling or swimming in the sea where the bottom is sandy and the water shallow, but now and then comes ashore and buries itself in the dry sand, all but its stalked eyes, as we found this one.
A smaller, lighter-colored, and more square-bodied cousin of this crustacean, called the ghost-crab, is very common on southern beaches, where it digs slanting burrows deeply into the sand. Prof. A. G. Mayer tells us that it is a scavenger, feeding on dead animals, and also catching and eating beach-fleas. It is at night that they are most active. "As they flit rapidly about in the moonlight their popular name of ghost-crab seems remarkably appropriate. As one approaches they dash off with great rapidity, and will often rush into the water, although the gray snappers are swimming close along the shore in order to devour them."
What have you found now? It appears to be a horseshoe-shaped skillet, or frying-pan, made of brown parchment, with a long spike loosely hinged to one side for a handle, and a big crab lying on its back in the pan. No wonder you are surprised. The first white men who came to this country were equally so, for nothing of the sort is to be seen in any other part of the world, except in the Malayan islands. If we search we are likely to find one alive and creeping about, and then we shall see that the skillet is a broad shield covering the back of an animal, and that what we thought was the crab inside it, is its body and legs. When you come to study natural history more deeply you will learn many very interesting things about this strange inhabitant of our beaches, which is known as a horseshoe-crab, or king-crab, and also as limulus. It is the sole remnant of a great tribe of sea-animals called trilobites, which became extinct ages ago.
One more curiosity must be mentioned before we quit this first short walk upon the open beach—what the fishermen call the mermaid's-purse, of which, see, you have found several.
It is an egg, but you never would have suspected it, would you? Examine it. It is about two inches long, and made of a hard, black, leathery substance, and at each of the four corners there is a little projection about an inch in length. It is the empty egg of a skate—a fish of the shark tribe with a broad, flat body and a long whip-like tail—from which one of these curious fishes has just escaped. How do you think it got out of the egg when the time came for it to be hatched? Just look at this empty case, and you will see. At one end there is a slit running across it almost from one side to the other, made in such a manner that the little fish could easily push its way out, while none of its enemies could push their way in. So the baby skate lay in its cradle in safety till the time came for it to pass out into the sea.
But here is an egg made in just the same way, with one little difference. Instead of having a short straight projection at each corner, it has a long, coiled, twisted one, much like the tendril of a grapevine. That is the egg of one of the small sharks called dogfish, which are so called because they swim about in parties or packs of fifty or sixty together, driving herring and other fishes before them, as dogs drive deer. The skin of a dogfish is as rough as a piece of sandpaper.
When the eggs of this fish are first laid, the twisted projections at the ends coil themselves round the stems of weeds growing at the bottom of the sea, and hold them so firmly that they cannot be washed away; and at each end there is a small hole, so that a current of water may always flow through this egg-case and over the little fish inside—something of just as much importance to it as is a supply of air to a land-baby.
II
SEARCHING THE SHORE AT LOW TIDE
The shore of the eastern United States, at least south of New York, is formed of a line of long narrow islets whose outer beaches, and the sea-floor for miles out, are pure sand. They support very little life, as has been said. Behind them, however, are shallow bays and sounds, in which the water, though salt, is usually warm and still; mud gathers upon the sand, and eel-grass and other water-weeds grow in abundance. Here is excellent ground for naturalists, old or young, and in a single walk you can discover enough to surprise you greatly. We must go when the tide is low, and it will be a good idea to take our rubber boots, so that we may not be afraid of the wet mud. We will also take a small spade or strong trowel, and some boxes and bottles.
What a lot of clam-shells are lying about the shore! There are two kinds, the soft clam and the hard clam; but none of them are alive.
How is this? We have already learned, you will remember, that the clams are bivalves; that is, the shell is in two pieces, hinged together by an elastic ligament over the back, and covering each side of the animal. The soft body is attached to each shell by a strong muscle, by which the creature can pull the shells tight together, and so cover itself completely. When it wishes, however, it lets the shells spring open somewhat, so that it may put out from between their lower edges its muscular "foot," and perhaps move about, while out of the front end it stretches a double-barreled tube, called its siphon. Down one of the tubes is sucked a stream of water which not only bathes the animal's gills, or breathing organs, but carries minute floating particles of food into its stomach, after which the waste water is forced out of the other tube.
Now you will understand what we shall see, and are ready for the answer to our question. You never find live clams crawling about the sand, because they live buried in the mud.
Now let us put on our boots and look about on the surface of the wet mud. Do you see ahead of us those little jets of water come spouting up into the air as if squirted out of tiny syringes? Every one of these little jets is thrown up by a soft clam, which lies perhaps several inches deep in the mud, with its siphon stretched up to the surface and held full of water, waiting for the tide to come in and refresh it. When it feels the jarring of our footsteps it squirts the water out; and you must dig deep and fast if you want to catch it. This is what those men are doing out there on the flat—digging out clams with long spades, and filling their baskets for market. Thousands of little ones lie in the mud, not yet big enough to eat.
The soft clam is a shapeless sort of mollusk, with a thin chalky shell, not at all pretty; but the hard clam, or quahog, is thick-shelled and regular in outline; and in an end-on view takes the shape of an ace of hearts, like the Venus-shell, or the cockle, which is so commonly eaten in Europe. This species likes much deeper water than the soft clam, and is gathered mostly from boats, by a kind of rake; but we shall no doubt find a few up here. Do you see that scratch in the mud? It looks like a trail, and there at the end is the traveler himself, standing upright in the mud like a half-buried wedge.
This shows another difference between the two clams; for while the soft clams and their relatives, such as the pretty razor-fish, and the "old maid" of English bays, never leave the burrow where they begin life, the quahogs slowly wander about all the time. As for the scallops, they fairly skip and jump.
What are scallops? Well, we shall hardly see much of them, for they live in deep water; but their half-shells are to be seen cast up everywhere, for they also are bivalves. Our common ones are usually about the size of a silver dollar, and fan-shaped, the thin shell ribbed like the sticks of a fan, and the margin crinkled, and they are variously colored, but mostly in tints of reddish and yellow.
Several small bivalves and sea-snails may be added to our collection from this uncovered bay-bottom, and here and there spaces are fairly sprinkled with little blackish fellows about the size of hazelnuts. When we have gathered a handful we shall find we can sort out three or four kinds.
A very curious denizen of the tide-flats of our Southern States is the pinna, a large bivalve with thin horny shells shaped like a slightly opened fan, which lies deeply buried, point down. The edges of its shell come just at the surface, and are exceedingly sharp, so that barefooted persons have to be very careful how they step where pinnas are common, as on the Gulf coast of Florida, and it is no wonder the people there call them razor-fish. Lying there in the mud, with its shells parted, and a current of water always sucking down what we may call its throat, it forms a regular trap for little fishes and other small creatures. The instant one swims between the shells, they close and the unfortunate curiosity-seeker finds himself in a prison from which there is no escape.
When a young pinna settles down in its place it at once anchors itself to some rock or fixed thing below it by throwing out from near its lower, narrow end a bunch of very strong threads, which hold it down so firmly that it takes a very hard pull to tear them away. This anchor-cable is called a byssus.
A short distance from us a narrow stream wriggles through the salt marsh, and we can get into a rough little boat and paddle down toward that old wharf whose weedy piles are covered with interesting things, which we may examine now that the ebbing tide has left them uncovered for a few hours. The peaty banks, with their growth of harsh salt-grass and algæ, will keep our eyes busy as we float along the black and winding creek.
Now we shall get acquainted with some of the crabs. Look sharply down into the water and you will see the large "blue" crabs which we buy in the market, and eat, swimming near the bottom or crawling over the mud near the banks. There is one, now. He doesn't look very blue, nor very appetizing, does he? His back is brown and muddy, to be sure; but his big claws and lower plates have much more blue upon them than has any of the other large crabs, and so he gets the distinguishing name.
But, you say, you have heard of "hard-shell" and "soft-shell" crabs, and want to know the difference? It is simply a difference of condition. If you will turn to page [397], you will find described that extraordinary process by which crabs grow, by throwing off their stiff old skins and expanding to fill the elastic new one which has formed underneath. Before this change, the creature is a "hard-shell" in fishermen's language, and just afterward, when he is large and tender, he is naturally a "soft-shell"; and then is the time to eat him.
Notice how the black masses of peat along the banks are honeycombed with holes, as if somebody had been pushing down the point of his umbrella. They are the homes of little fiddler-crabs, which scuttle into them by the hundred as we approach, and then creep up to peer out after we have passed by, and make sure it is safe to go abroad again. In other holes live two other sorts of burrowing crabs. One is the little mud-crab (Panopæus), which is a peaceful cousin of the fiddler; and the other is the sand-crab (Ocypoda) whose peculiarity it is to be perfectly sand-colored, so that it is almost impossible to see him until he moves; consequently he is commonly found only in the sandy places.
As we float nearer to the mouth of our winding creek, we begin to notice bunches of mussel-shells, clinging closer to each other than grapes in a bunch; and when we try to pick one up we find it quite immovable. In fact, they are anchored to the roots of the grasses, and to each other, by a bunch of byssus threads from each mussel, like those of the pinna; and these threads are so strong that they can hold the mussels firm against the beating of the waves, so that a shore which is thickly covered with mussels is safe from wearing away. You may see an example of this in the tideway at the mouth of this very creek, and masses of mussels strengthen the supports of that wharf we are approaching. If you were to go near the town of Bideford, England, you would see a bridge of twenty-four arches, which runs across the Torridge River close to the place where it joins the Taw. Now that bridge is held together by clusters of mussels! The force of the stream is so great, that if mortar is used to repair the bridge it is very soon washed away. So from time to time large boat-loads of mussels are taken to the spot and shot into the water, and they fasten themselves so firmly to the bridge by means of their byssus threads, that they actually hold together the stones of which it is built!
These binding mussels are mostly of the smooth, dark-blue sort which are found on both sides of the Atlantic, and in Europe are gathered and eaten. When our people become a little wiser and more economical, we also will take advantage of this great stock of excellent food right at our doors.
But in the bunches which are scratching the side of the boat as we glide along close to the bank are some which are much larger, though smooth, like the edible mussels. They are an American species. Then here and there in peat you may see a sort whose shell is rough, with ridges spreading out toward the large end, and these you may call horse-mussels.
Now we have got down to the boat-landing toward which we have been lazily drifting, and we will twist the chain around one of the piles that support it, and stop long enough to take a look at one of them. Most of the time each pile is under water, and therefore is overgrown with a thick "fur" of plants and animals.
You will see that most of this fur consists of seaweeds, but their leaves are often the resting-place of several sorts of lowly animals. Indeed, you must look sharp to make sure whether some of the feathery tufts that droop from a dank old post, or spray out so beautifully in the ripples at its foot, are plants or animals. We will not talk about that just now, but wait till we take our excursion to the rocky shore, where we shall find barnacles and corallines and sea-mats and polyps bigger and better than here.
But do you see between those green fronds that roundish yellow object about as big as a filbert? Touch it gently. Did you see tiny jets of water squirt out of two little nozzles on its surface? That gives it the name of sea-squirt. Into one of the nozzles, when the tide comes over it, is constantly sucked a current of sea-water which passes into a stomach-like cavity, where the minute particles of food in the water are caught and digested; then the water passes on through another cavity where the blood receives its oxygen, as in our lungs or a crab's or fish's gills, and then rushes out. So this little object is a real animal, with heart, blood, stomach, and something in the way of nerves—enough, at any rate, to feel your touch, shrink, and squirt out all the water in its bag-like body.
There are a good many kinds and forms of these ascidians, as naturalists call them, some larger, some waving about on the summit of stalks like lily-buds, and some clustered into colonies grown together, which form bands around the stems of plants, or make masses called "sea-pork" by the fishermen, or float in chains, by millions, on the surface of the open sea.
Here, too, are small red and yellow sponges; some coarse little sea-anemones, etc.; and wandering over the whole, feeding upon one or another of these, and cleaning the polyps and polyzoans off the algæ, are a sort of marine daddy-long-legs, called no-body crabs, because they seem all legs and look crab-like.
It isn't very sweet-smelling under this damp old wharf, where the rising tide is beginning to bathe the piles, and one after another plants and animals are expanding as they feel the refreshment of the water around them; and we will move away as soon as we have dug a few things out of the mud, soon be hidden by the tide.
Let us run the bow of our boat up on that soft black slope, and see what we can find by leaning over the side. Just look at this hairy object, for instance, which has been left by the retreating waves. It seems like a big brown slug covered with bristles and is not very pleasant to handle; but you needn't be afraid of it, and you mustn't be squeamish. Just dip up some water in that pail, and rinse it till you have washed every scrap of mud from its bristly coat, and then look at it in the sunlight. Do you think it is dull and dingy now? Did you ever see a more beautiful creature? This animal is called the sea-mouse, although really it is a kind of sea-worm and if you will turn back to page [429] you will find it described. The reason why its coat is always so dirty is that the bristly hairs which cover it act as a sort of filter, and strain out the mud from the water which is passing to the gills. But these hairs have another use as well. Each one is really a sort of slender spear, with a barbed tip, the edges being set with a number of sharp little points, all directed backward, forming a capital protection from such creatures as the fishes, a great many of which would be glad to feed upon sea-mice if it were not for their coating of spines.
Do you see those twisted little coils of muddy sand scattered about on the mud? Those are the casts of lugworms, which are made in the same way as the casts of earthworms seen in our garden-paths on damp mornings; in fact, these lugs are just marine earthworms (see page [427]), and like them eat their way down into the mud, swallowing mouthful after mouthful for the sake of nourishing particles in it, and then voiding the useless remainder.
Perhaps you wonder how it is that the burrows of the lugworms remain open. Why doesn't the mud close in behind the animal? The fact is that the worm is always pouring out from its skin a sticky slime which quickly becomes quite hard and firm. And this binds the sandy mud together as the worm forces its way down, and forms a kind of lining to its burrow, just like the brickwork with which we line our railway tunnels.
You would scarcely suspect what interesting and often beautiful worms lie buried in the mud or muddy sand of sea-beaches and salt marshes. They occur elsewhere, too, as upon weedy rocks, while a great many kinds dwell upon or within the bodies or coverings of other animals, from whales to periwinkles and crabs.
Most of the beach-worms belong to the highest class of the tribe, called annelids because their bodies are made up of ring-like segments (a little ring in Latin is annellus), as you can easily see by examining one of the angleworms you dig in the garden for fish-bait. The red lugworm, or "red thread," as it is often called, is another plain example of this structure.
Digging down by low-water mark we are likely to unearth one or more of the ribbon-worms which, when they are large, seem rather terrible. Their bodies are flat, so that when they swim they move through the water like a floating ribbon, and they have been found five or ten feet long and as wide as your palm. Such big ones are rare, however, and we are more likely to have to deal with one two or three feet long and less than an inch broad. They are active creatures, burrowing into and through the mud in search of other worms upon which they feed, and which they seize by thrusting out a sticky proboscis. There is also a smaller one, pink in color, while the bigger species is yellowish.
Though we may not dig up a ribbon, we are pretty sure to turn out a nereis, or clam-worm, as the fishermen call it—a reddish creature a foot or two long, looking like a centipede, for there is a pair of minute feet on each ring, and every foot is feathered with a gill. This also is a ravenous enemy of all other worms or animals it can overcome; and young clams, limpets, starfish, and other protected creatures must be thankful for their armor when it comes crawling near them. Its rich green and salmon coat has no charm in their eyes, you may be sure. But the nereis itself must have its fears, for it is not only hunted by ribbon-worms, by a big active annelid called "four-jawed," and by winkles and dog-whelks, but is well liked by various fishes; and, last misfortune of all, it is constantly sought by fishermen for bait. In spite of all this, clam-worms of all kinds remain immensely numerous all along the coast. On calm summer nights they leave their burrows, swim up to the surface at high tide, and cast out vast numbers of eggs, from which presently hatch little pear-shaped larvæ, which swim about a short time, when the few that have survived settle down, change to the worm-like form, and burrow into the mud.
When we come to explore the rocky places, and peer into the still pools left by the ebb-tide among the reefs and boulders, we shall make the acquaintance of some other worms that display themselves in such places as in a natural aquarium.
III
ON THE ROCKY LEDGES
There are practically no rocks on our Southeastern coast, so that we must imagine ourselves now somewhere in New England—let us say on the southern shore of Rhode Island. All along the north side of Long Island Sound, about Buzzards and Narragansett bays, and then from Boston Harbor right up to Labrador, the shore is rock, with many headlands, reefs, and islets, separated by shallow coves or by swift tidal runways. This is good hunting-ground for the seaside naturalist, and one visit to the space left uncovered at low tide will be no more than a glance at what might easily keep us busy and interested a whole summer through.
As the water ebbs away, the tops of the ledges and boulders emerge like the hairy heads of some sea-monsters, for they are mostly overgrown with long tresses of olive-brown rockweed and green ribbons of sea-cabbage, (Ulva), which trail, wet and shining, down their sides. Step carefully, for it is all extremely slippery. Do you hear that continual popping under your feet? That means that you are crushing the little bladder-like swellings strung like big beads on the stems of the rockweed. They are filled with air, and keep the long and heavy stems and leaves of the weed afloat, as you may see if you look down where it is swishing back and forth in the lapping waves. These plants must be exceedingly strong to resist the pulling and pounding of the surf in a storm; and their power to keep afloat by means of these gas-filled "bladders" is of assistance, not only in enabling them to hold together, but to form a breakwater which protects the rocks and ledges they cover from being beaten to pieces by the surf.
Underneath and upon these masses of seaweed hide a great quantity and variety of small plant and animal life, some of which we shall be able to find and study, though a large part of it requires more thorough work than we have time for, and the aid of a microscope.
But first let us look at some of the bare places, where there is no seaweed. Here is a black rock with white patches of rough little things growing upon it by the hundred. They are not mollusks, however, but rock-barnacles (see page [407]), which English boys call acorn-shells. They are small and distant cousins of the crabs.
The story of these barnacles is a very curious one. When first they hatch from the eggs which older barnacles have cast out into the sea, they are not in the least like their parents, but are queer little round-bodied creatures, smaller than pin-heads, with six feathery legs by which they paddle about, one round black eye, and two feelers. Every two or three days they throw off their skins, as caterpillars do, and appear in the new ones which have formed underneath; and every time they do this they change their shape, so that sometimes they are round, and sometimes oblong, and sometimes almost triangular!
At last they reach their full size. Then they cling with their feelers to the first rock, log, or other hard thing they come to, and pour out a drop or two of a very strong cement, which hardens around them and fastens them firmly down. After this they never move again; but a day or two later they change their skins once more, and appear as perfect acorn-shells.
Now look at one of them carefully through this magnifying-glass. Do you see that there is a little hole in the top of the shell, which is made of several pieces? That is the hole through which the animal inside fishes for food. If you were to watch it when the rocks are thinly covered with water, you would see that it kept poking out a net-like scoop, and then drawing it in again. This net really consists of the hairy legs; and as they wave to and fro in the water they collect the tiny scraps of decaying matter on which the little creature feeds. They also bear the gills by which the barnacle refreshes its blood.
You must be very careful not to knock your hand against these shells when you are hunting about among the rocks, for their edges are so sharp that they cut almost like knives.
"Another sort of barnacle," you say you have found? No: there are other sorts—the strange goose-barnacle, for instance, which attaches itself to the bottoms of ships—but what you have found is one of the limpets, and that is not a crustacean, but a gastropod mollusk. It is shaped like a tiny rough mountain, or rather like a volcano, for you see there is a hole in its summit; and we call it the keyhole limpet on account of the shape of that hole. Pick it up. Oh! you can't, eh? Of course not. Pull and push as hard as you like, you won't be able to move it, nor can the heaviest waves wash it off.
Would you like to know why?
Well, the reason is that a limpet clings to a rock by turning the whole lower surface of its body into one big sucker; it presses it tightly against the rock and then lifts the middle part. The consequence is that a chamber is formed in which there is nothing at all—no water, not even air; and, as happens when you lift a brick with a small leather sucker, the weight of the atmosphere presses down upon it so strongly that no force you can bring to bear will pull it off.
However, a limpet is not gripping the rock all the time with such vigor; he would literally be tired to death, and starved to death, too, if he didn't ease up most of the time. It is only when he is alarmed by a touch that he clamps down. If you want to get him free, just wait till he loosens up, then hit him a sudden sharp blow on one side with a stick or stone, and knock him off. Then you will be able to examine the soft body and see how he is built.
Limpets are vegetable-feeders, and when the water is still, or absent, they creep slowly about the rock, nibbling the tiny vegetation on its surface. Another interesting fact in limpet-life is told on page [421].
Another kind of limpet is very common on those rocky shores, which is shaped somewhat like a loose round-toed slipper or a French sabot. This is the slipper-limpet, or half-deck, as fishermen call it.
On the lower rocks near the water, and hidden in among the wet seaweeds, lie many small spiral gastropods which we call periwinkles. Two of the commonest kinds are littorinas, marked with fine lines and colors in various ways. Another, reddish with chestnut bands, is named Lacuna; and you may pick up several kinds of small blackish ones, such as Bittium, or of light-colored ones, as Rissoa, which is prettily mottled; while numerous in some places is the purple-shell or Purpura, which is interesting because it belongs to the European shores as well as to ours, and because from it the ancients gathered some of their purple dye, although another mollusk (the murex) furnished most of it. But in old times the coast people, both of old England and New England, obtained from this little mollusk an indelible violet ink with which to mark their clothes.
Would you like to see a little of this dye?
Very well, you can easily do so. Look! Hold the purpura over this sheet of white paper, and give the animal a little poke with the head of a pin. There! It has squirted out a drop of liquid upon the paper. It does not look much like purple dye, does it? It looks very much more like curdled milk. But lay it in the sunshine and notice what happens. Do you see? It is turning yellow. Now a blue tinge is creeping, as it were, into the yellow, and turning it to green. The blue gets stronger and stronger, till the green disappears. And at last a crimson tinge creeps into the blue, and turns it to purple.
Another curious thing about the purpura is the way in which it lays its eggs. It fastens them down to the surface of the rock by little stalks, so that they look like tiny egg-cups with eggs inside them; therefore when these eggs hatch, several little purpura come out of each cup.
All the small periwinkles feed upon the algæ, but with the purpura, which seems to live mainly on young barnacles, we come to a lot of flesh-eaters—small mollusks of prey, as we might say.
There are several spiral sorts, mostly from one to two inches long, whitish and heavily ribbed, which are sometimes called dog-whelks; but the worst one, which lives by thousands on the beds of planted oysters scattered all along the shore of Long Island Sound, is known to the oystermen as the drill, or borer. It is particularly fond of the flesh of oysters, and cares nothing for their shells, as it carries in its mouth a drilling instrument (see page [419]) by which it can bore a round hole through the poor oyster's armor. In this way it destroys many thousands of dollars' worth of valuable oysters every year.
It was pretty certain we should find a starfish down near low-water mark, and here is a fine one.
Starfishes are among the oddest of sea-animals; for one reason, because they have so many legs. Perhaps you did not know they had any legs at all; certainly you can see none when you pick up a dead specimen on the beach. The fact is that a starfish keeps its legs inside its body, where there are a lot of organs protected by its hard, limy hide; and when it wants to use them it pokes them out through little holes on its under or grooved side, and fills them with water.
You would like to see its legs, no doubt. Very well; you shall. This starfish is still alive: we can easily see that, for when we pick it up its rays stand stiffly out; but if it were dead they would be quite soft and flabby, and would hang down. So we will put it into a shallow pool of clear sea-water, and see what happens. There! did you notice that it moved one of its rays? See, the one in front is being slowly pushed forward. Now the rays behind are being drawn up; and now that they have taken a fresh hold the front one is being pushed forward again. The starfish is really walking! What will it do when it comes to a stone? Why, walk over it! What will it do when it comes to rock? Why, climb up it! Now take the starfish out of the water. Turn it over on its back. There! do you see? On the lower surface of every ray are hundreds of little fleshy objects waving about in the air. Those are its "feet," or at least its means of walking; and each has a sort of cup at the end which acts as a sucker. By means of these the starfish can cling tightly to the surface of a stone. So by using first the little sucker-legs on one or two of its rays, and then those on the others, the starfish is able to crawl about quite easily.
The starfishes live upon animal food—mainly other mollusks, which they kill in a very curious manner. When, in crawling about, they come upon a whelk or clam or oyster, they creep over it and clasp it in their five arms in a murderous embrace from which there is no escape. Even if the creature can move off, its captor clings to it with its hundreds of tiny suckers, and rides along with it like that Old Man of the Sea in Sindbad's story.
Now if you look again at our specimen you will see on its under side, a small pit in the center of its body, closed by five points. This is the mouth, and the points are sharp. As soon as the starfish has a grip upon its victim the mouth opens and there is gradually pushed out a strong membrane which is the creature's great loose stomach. This envelops the animal, shell and all, or as much of it as possible, and soon begins actually to digest the flesh. When the meal is finished the starfish draws back its stomach and leaves only the empty shell of its prey.
These voracious starfish are a worse enemy to the cultivated oysters than are the drills; and, having an abundance of food on the thickly planted beds, they become extremely numerous, so that it costs the owners of the beds much money each year to gather them off the beds by means of a sort of great rake called the tangles. Otherwise the oysters would soon be wholly destroyed. The men used simply to tear to pieces what they caught and throw them overboard again; but they soon learned that this was worse than useless, because each half, or even a single arm, would not only go on living but would reproduce all the missing parts; so that in trying to kill one starfish they had brought to life two or perhaps even five, which was very discouraging. Nowadays, therefore, all captured starfishes are brought ashore and left there, and often are made use of by being ground up with oyster-shells, fish-bones, etc., into an excellent fertilizer.
What is that greenish-gray object covered all over with spikes? It is clinging in a little hollow of the rock, half hidden in seaweed of the same color.
Ah! that is a sea-urchin, and although it looks so very unlike them it is really a kind of first cousin to the starfishes. Here is a dead one from which the spines have been knocked off. Just look at it carefully, and you will see that it is very much like a starfish rolled up into a ball. See, you can trace the five rays quite easily, and if you look at it through a strong magnifying-glass you will find that its surface is pierced in hundreds of places with tiny holes through which it can poke out little sucker-feet, just as the starfishes do.
Look again at the shell from which the spines have been knocked away. Do you see that it is covered all over with little pimples? Now on every one of these pimples a spine was fastened by a kind of ball-and-socket joint, the pimple being the ball, and the socket lying inside the base of the spine; and by means of special muscles the animal could move the spines about, just as though it were a kind of hedgehog. In fact, this is the reason why it is called sea-urchin, for urchin is an old name for hedgehog. So, when a sea-urchin crawls about, it does so partly with its sucker-feet, and partly with its spines as well.
Sometimes, however, these creatures use their sucker-feet for quite a different purpose. They poke them out as far as they can from among their spines, and then take hold of little stones, small pieces of broken shell, and other bits of rubbish which they find at the bottom of the sea, and cling to them very tightly. The consequence is that you cannot see the animal at all, for it is quite concealed by this curious covering, and unless you were to take it out of the water, you would never have the least idea what it really was.
Now look at the mouth of this spiky sea-urchin. You will find it in the very middle of the lower part of the body. Do you see what great teeth it has? There are five of them arranged in a circle as in the mouth of a starfish, and they are made in just the same way as the front teeth of a rat or a rabbit, that is, they never stop growing all through the life of the animal, so that as fast as they are worn away from above they are pushed up from below, and thus always keep just the proper length and sharpness.
Sea-urchins are rather few and small along the shores of southern New England, but more numerous northward, and on rocky bottoms offshore. On the offshore bottom there lives also a queer sort whose shells are often cast up and are well known to the children as sand-dollars.
These are about the size and shape of one of mother's cookies, and are covered with a stiff brown fur of short spines. On one side—the under one—is the little mouth, and around it the faint outlines of five radiating arms, each sketched, as it were, by a double row of "pin-pricks" where the almost invisible feet are pushed out. These sand-dollars are creeping about at the bottom in myriads where the water is a few fathoms deep; and storms cast up thousands upon the beaches or into the tide-pools, where very likely we may find some in the course of our next visit to the ocean-side.
IV
BETWEEN TIDE-MARKS
We must start early on our walk today, as soon as the tide falls away from the piece of rocky shore we have in mind, so that we may have plenty of time; for the field which we have left until the last is the richest the seaside naturalist has to explore.
As the sea sinks away it uncovers not only the weedy ledges which we studied the other day, but also spaces between them of low rocks and loose stones half sunk in mud and sand. There is much to interest the botanist, too, but he will have to look out for himself. We have more than enough to do to look after the animals.
Many dead shells are lying about, showing the various species of shell-fish which inhabit this shore or the waters of the offing. Some of them we already know, and others we can never expect to get alive except by dredging. Such are the scallops, which rarely come up as far as low-water mark, in spite of their wandering habits; and the jingleshells or goldshells, although these, like the young oysters to which they are closely related, may usually be found clinging to stones, where they seem swollen scales or "blisters" of thin amber, or gold-colored horn. There is one—let us examine it. We can't pick it off, or even pry it off; but when we slip a knife-blade slowly beneath it, it comes loose, and we discover that this queer creature is a bivalve mollusk looking (and tasting) like an oyster, and with a small flat shell underneath the bulging top one. In this undershell is a large hole, through which passes a stout stony stalk which anchors this creature as firmly as an oyster is fixed by the cementing of its undershell to whatever it has attached itself when young.
The jingleshells are extremely numerous all along the coast south of Cape Cod, wherever the water is no more than about seventy feet deep, especially in Long Island Sound; and the oystermen gather them from the beaches and from their dredgings, and scatter their shells over the floor of the sound as "seats" for young oysters. They are especially useful for this purpose because they are so slight and brittle that when, as often happens, two or three minute oyster-larvæ settle down on one of these shells, they will, as they grow, break it apart by the strain, and then each oyster, relieved from the crowding of its mates, will form a round, nicely shaped shell instead of a narrow or misshapen one, and consequently be more valuable when it comes to be dredged up, after a couple of years or so, and offered for sale.
This rough space between tide-marks is a fine place for crabs. We have seen some of these creatures already, elsewhere; and our book (see [Chapter XXXV]) has already instructed us as to the general characteristics of crustaceans. Here, scrambling about the ledges just under water, are big rock and Jonah crabs, but not so many of them as you might see in Maine. Both are eaten when "soft-shells," but are not so good as the blue crab. Here, too, are lively and pugnacious fiddlers and some green or stone crabs, wonderfully active little creatures, which in England are sent to market, but on this side of the ocean are used only for bait.
Still more comical and interesting is one of the spider-crabs, which may be called thornback. It has a little body, but very long legs, so that a big male thornback might cover eighteen inches in the stretch of its legs.
Do you see how long his great claws are, and how his back is covered all over with tiny hooked spines? It is quite easy to understand why the name of thornback was given to him. But how is it that all those tufts of seaweed are growing on the upper part of the shell?
Well, the answer is a very odd one. The crab planted them there himself! The fact is that when he is lying down at the bottom of a pool he does not want to be seen, for fear that the animals upon which he preys should take alarm, and escape before he can catch them. So he actually pulls up a number of little sprigs of seaweed, and plants them on his back one after the other, pressing the roots down with his claws till at last they are held quite firmly by the little hooked spines with which his shell is covered! Then as long as he keeps quite still he is perfectly invisible, and his victims may even crawl over him without suspecting that they are in any danger.
Stranger still, if a thornback crab which has covered his back with seaweeds should be placed in a tank in which sponges are growing, he will soon find out that he is not nearly so well hidden as he would like to be, and will get very uneasy. Before long he will discover what the reason is, and will actually pull all the sea weed off his shell, and plant sponges on it instead.
Here, too, scampering and rattling about among the pebbles, are lots of hermit-crabs, dragging after them the shells in which they have ensconced their soft hind bodies, as is described on page [402]. And under the stones—turn them over and you will see—are dozens of strange little half-transparent creatures which you might easily believe were insects, but which really are diminutive cousins of the crabs and crayfish named amphipods and isopods, and so forth. You may find under some stone one of the tubes made by a certain species, composed of grains of sand glued together by sticky threads much like spiders' silk. These minute crustaceans exist in vast multitudes near the surface of the ocean at certain seasons, and form the principal food of the whalebone-whales, which gulp them down wholesale. Some of them, also, are parasitic on fishes.
But what is the curious little creature clinging flat upon this rock among the weeds? It looks like some sort of pill-bug half an inch long, doesn't it?
Ah! that is a chiton. It is really a kind of shell-bearing mollusk, like the whelk and the periwinkle; only instead of having its shell made all in one piece, it has eight shelly plates on its back, which overlap one another just like the slates on the roof of a house. Just touch it with your finger. There! Do you see? It has rolled itself up into a ball, just like those pill-millepedes which you may find in the garden. It always does this if it is frightened. And its shell is so stout and hard that as long as it is rolled up it is quite safe from nearly all its enemies.
If you were to hunt about among the rocks quite close to the water's edge when the tide is at its lowest, you would most likely meet with a number of chitons, and you would be surprised to find how much they vary in color. Some are ashy gray all over; but a great many are streaked and spotted with brown, and pink, and orange, and lilac, and white. But the strangest thing of all about chitons—there are far larger ones in the warmer parts of the world—is that some of them have nearly twelve thousand eyes scattered about all over their shells!
But we are lingering too long by the way, for our real destination to-day is that fine pool over there. It is a basin among the ledges, filled with quiet sea-water left by the retreat of the tide, half-floored with sandy mud, and its edges fringed with feathery seaweeds, corallines, and hydroids. Here is a capital home for the little folk of the sea, where there is always fresh clear water, but where only a part of the time do the surges pound, and then never with full force; furthermore, a wall of rocks protects the nook, and enemies can rarely enter to destroy the peaceful society.
In warmer parts of the coast, as in the Gulf of Mexico, or upon the Pacific coast, or most of all in some of the tropical islands which now belong to the United States, such a pool would be brilliantly carpeted with sponges, sea-anemones, coral-polyps and corallines, of which you may read on pages [431 to 435]. The water of the North Atlantic, and the winters of its American coast, are too cold, however, to allow any but a very few hardy species of these lowly sea-flowers to grow in our pool; but there are quite enough to keep us busy during the hour or two left before the returning tide creeps over the jagged rim of the basin and drives us away.
Here, for instance, is half an oyster-shell looking as if it had been bored full of holes with bird-shot. It could hardly have been any boy's target though; for, see, we can find many such fragments. There is one under water. Take it out and you will find every one of the hundreds of little pits filled with a yellow spongy material. It is real sponge, called the boring-sponge, because it riddles all sorts of old shells until they fall to pieces. This is a good thing, for then they are gradually ground to powder and dissolved in the water, and so help to keep it supplied with the lime needed by living animals for their shells.
But other sponges help in this work. One is a brilliant crimson, and spreads a velvety mantle over the shell, from which rise branches as big as your fingers. We may probably discover among others here the pretty urn-sponges, like clusters of yellow or gray goblets about half an inch high. On the reefs of the Gulf coast of Florida, you know, several sorts of sponges grow to great size and are gathered and prepared for use—a trade which furnishes employment to hundreds of men.
But this clear pool holds more beautiful things than sponges. If we are fortunate we may find a sea-anemone. Do not fancy from its name that it looks anything like the pretty pink and white anemones that delight you in the woods in the spring. It does, indeed, look something like a clove-pink, or some sorts of chrysanthemum, when it is fully expanded, yet it is not a flower at all, but a true animal.
Its body is shaped like a barrel, or sometimes more like a tube, with a large throat leading into a big stomach which is held in position in the center of the body by six partitions radiating like the spokes of a wheel from the stomach to the tough outer skin. Between these are other shorter partitions extending inward from the skin, but not reaching the stomach.
This is the type of structure in the polyp family, which the sea-anemones represent; and the stony coral-polyps are built on the same plan, only there the outer wall and the radiating inside partitions become hardened plates of lime as the animal grows, and form, when many grow into a solid mass, the immense coral reefs described on page [433].
The New England coast has several small sea-anemones, and one handsome one, sometimes as big as a teacup, a few of which dwell in our pool. Just come, very quietly, over to this side, and gaze down through the clear water upon that reddish block of stone. Do you not see that large brown tuft, quivering and moving like a chrysanthemum each petal of which was alive? That is the brown sea-anemone; but some specimens show much brighter tints.
Ah!—did you notice how that minnow turned and fairly flew as he felt a touch of one of those waving petals? No wonder he was in such a hurry to escape from its clutches, since he knew quite well that the grasp of those arms means death. For every one of them is set with scores and scores of tiny oval cells, made in such a way that they spring open at the slightest touch. And inside each cell is a slender poisoned dart, which leaps out as soon as it is opened.
So, if the minnow had waited a few minutes longer hundreds of these little darts would have buried themselves in the soft parts of his body and stung him to death, and then the anemone would have swallowed him!
Now just touch the anemone with the tip of your finger. You need not be afraid to do so, for its little poisoned darts are not nearly strong enough to pierce your skin. There! do you see how its arms at once come closing in? It seems to be pushing them right down into the very middle of its body. Now they have entirely disappeared, and you cannot see them at all. The animal looks just like a shapeless lump of jelly.
Yes, it always does that when it is frightened, and also if it is left high and dry when the tide goes out. And when it catches a good-sized victim and swallows it, it generally remains closed up for at least a couple of days.
Now let us tell you another curious thing about the anemone. It looks as if it were growing out of the rock, doesn't it? If you try to push it loose, you will probably kill it before you succeed. Yet it can release it's sucker-like grip, and move about if it wishes to. This is only one of many very interesting things to be learned about these lovely creatures.
And here is another very beautiful thing which you must not miss. One would think the dark rock under the water had blossomed out into a small bed of filmy bluish pinks, only what you see is even more delicate and feathery. That is a patch of true corals; and it is most fortunate it was found here, for it is rarely seen, except when brought up in a dredge from water several fathoms deep.
Now let us see whether we cannot find some of the tube-worms which in feathery beauty are rivals of even the anemones and coral-polyps. Look down to the very bottom of the pool. Do you see that bunch of long, twisted tubes, which seem to be fastened to one of those big stones?
They are made by a very common sea-worm called the serpula, or shell-worm, for they are quite as often found attached to shells as to stones. This worm never leaves the tube it forms about it out of the limy mucus thrown out of its skin, so that it has no use for feet; consequently these have become simply a row of bristles along its sides, by which the animal can hitch itself up and down, or forward and backward, within its case. Sometimes it may want to draw itself back into its tube very quickly, to save its head being bitten off by some fish or ravenous worm. So along its back it has a row of between thirteen and fourteen thousand little hooked teeth, with which it can take a firm hold of the lining of its tunnel. And if it is suddenly alarmed it just raises these teeth, and then jerks itself back into its tunnel with such wonderful speed that you can scarcely see what has become of it.
Now let us lift the bundle of tubes out of the water, and examine them a little more closely. Do you see that each one is closed, just a little way below the entrance, by a kind of scarlet stopper? That shows that the worm inside is alive. The stopper is shaped just like a tiny cork, and whenever the serpula retreats into its tube it pulls this odd little stopper in after it, and so prevents any of its enemies from getting in and devouring it, just as gastropods close the aperture of their shells with the operculum.
If you were to put this bunch of tubes back into the water and watch it carefully for an hour or so, you would most likely see all the stoppers come out, one after another; and a few moments later you would see a bright scarlet tuft projecting out of the mouth of each tube. These tufts are the gills, by means of which the serpulas breathe. But at the slightest alarm the tufts would all disappear, and in less than a second every tube would be tightly corked up again, just as before.
On the Gulf coast of Florida, and throughout the West Indies, lives a larger relative of the serpula called "sea-flower," which secretes its tube upon the surface of large coral-heads, so that the tube becomes covered by the coral, leaving the opening still at the surface. "This opening," says Dr. Mayer, "is protected by a sharp spine, and is closed by the operculum of the worm when it withdraws its gills. When expanded these gills resemble a beautiful pink or purple passion-flower, about three-quarters of an inch wide."
In such pools, and in the mud among the stones near low-tide mark, lie buried several kinds of worms which poke their heads up into the water above them when the tide comes in, and expand tufts of pink, or crimson, or yellow gills and tentacles, the latter used to catch minute floating food—mainly the microscopic larvæ of various mollusks, worms, etc.—and also, in some cases, to drag to them the grains of sand out of which they construct their tubes. One of these is the fringed worm (Cirratulus) whose gills are like long orange-colored threads; and another the similar "blood-spot" (Polycirrus) whose great cluster of crimson tentacles about the mouth looks like a clot of blood on the sand. More often turned out by the naturalist's spade, however, is the tufted worm (Amphitrite) which dwells in a house made by itself, by taking a number of good-sized grains of sand, and sticking them together by means of a kind of glue which it pours out of its mouth, and which very soon "sets" and becomes quite hard, even though it is under water. This glue is so tough and strong that you can take the tube and give it quite a smart pull without tearing or hurting it in the least. And when the tube is finished Amphitrite makes that little fringe round the entrance by taking a number of very tiny grains and fastening them together in the form of threads.
There is one in this nook of our pool, now; and you may see the three pairs of blood-red tentacles which, with many pale yellow ones, the worm has thrust out into the clear water, breathing by means of some (the gills), and with the others capturing the invisible creatures upon which it mainly feeds.
The tubes of these worms usually run for several inches down into the sandy mud at the bottom of the pool, and are often carried down under the rocks, or big stones. So you will not find it very easy to dig them up. And if you startle Amphitrite herself, she will always wriggle at once down to the very bottom of her tubular fortress.
There! our four rambles are over, and although we have met with a great many interesting creatures, we have not seen nearly all that there is to be seen, either on the beach, or in the mud, or on the rocks, or in the pools which lie among them. But all the curiosities of the seashore may be found by those who have patience and know how to use their eyes.