Chapter XXXVIII: Annelids and Coelenterates (2)

How is it that all the trees, bushes, and plants are covered with threads of spider's silk, which often annoys us by getting on our hands or faces? Let us help you to an answer. This is the time of year when spiders are most numerous and most active; and many a spider trails behind it a thread of gossamer wherever it goes, and leaves it there. On many of the plants, bushes, trees, and fences you may see, if you look closely, very small spiders resting. Those little spiders have been taking a journey through the air--a sort of balloon trip. During the summer a number of spiders, all living near one another, had big families--a hundred or more in each. Perhaps you noticed in July and August spiders dragging about large white bundles: they were packets of eggs from which the young hatched. So many coming into the world together made it difficult to find food. So, one by one, the little spiders climbed low bushes or tall plants, and perched themselves on the tips of the topmost leaves. Then each poured out from the end of its body a slender thread of silk, which floated straight up in the warm air rising from the heated ground.

At last each little spider had seven or eight feet of thread rising up into the air above it. Then suddenly it loosed its hold of the leaf, and mounted into the air at the end of its own thread, higher, and higher, and higher, till it had risen several hundreds of feet into the air. Then it met a gentle breeze traveling slowly overhead, and traveled along with it, mile after mile, still resting on its thread. And when it wanted to come down, all that it had to do was to roll up the thread till there was not quite enough left to support it, and so it came floating gently down to the ground below. Then, having no more use for the thread, it broke loose from it and left it lying like a fallen telegraph wire across the tops of the bushes and fences and other things, where our faces brush against it.

What a pretty green fly this is sitting upon the fence, with delicate gauzy wings looking like the most delicate lacework!

Yes, that is a lacewing fly. Just notice what wonderful eyes it has. They look like little globes of crimson fire, and it is quite difficult to believe that a tiny lamp is not alight inside the head. This fly lays its eggs in a most curious way. Settling on a twig, she pours out a drop of a kind of thick gum from the end of her body. Then, jerking her body suddenly upward, she draws out this gum into a slender thread, which hardens as soon as it comes into contact with the air; and just as she lets go she fastens an egg to the tip. She then lays another egg in the same manner, and then another, and then another, and so she goes on till she has laid quite a little cluster of eggs--perhaps ninety or a hundred altogether. You would not think that they were eggs if you were to see them. You would be almost sure to think that the little cluster was a tuft of moss. Indeed, for a great many years even botanists thought that these eggs were a kind of moss, and put pictures of them in books of botany accordingly!

Look at these odd little black and white spiders. How jerkily they run; never moving more than an inch or so at a time, then stopping to rest, and then generally darting off again in a different direction. They are hunting-spiders, and are so called because they hunt for insects instead of trying to catch them in a web. You may see one of these spiders "stalking" a fly very much as a cat creeps up to a bird, and then suddenly springing upon it and leaping into the air with its victim firm in its grip.

Slowly the days grow shorter, the rains come more frequently, flowers wither, and the herbage shrivels. Insects die off, the birds one by one disappear quietly, or gather in flocks to journey southward, and the woods grow quiet and gray.

IV

WINTER

As we look out of the window on a landscape of snow, or of half-bare earth, frozen roads, and leafless trees, the world seems lifeless. But one who starts out for a walk, anxious to discover whether all nature is really dead, will soon find that it is very much alive, though much of it is buried in slumber. Let us test it.

As we take the well-accustomed path we cannot but contrast the bareness and silence with the activity and color and cheerful noise about us when a few weeks ago we strolled this way. The thought saddens and discourages us a little, when suddenly there comes to our ears

"_Chick-chick-a-dee-dee!_ Saucy note,
Out of sound heart and merry throat,
As if it said: 'Good day, good sir!
Fine afternoon, old passenger!
Happy to meet you in these places
Where January brings few faces.'"

There is the singer--half a dozen of them in fact--fluffy little gray, black-capped birds not much bigger than a man's thumb, dodging busily about the limbs of that old apple-tree, swinging with desperate clutch at the tip of a twig, hanging head downward to get at a morsel on the under side of the bough, and chattering all the time as though cold weather were no hardship at all.

What do they find to eat? Keep your eyes on one, and see if you cannot guess. He is pecking here and there at the bark, and swallowing something so minute we cannot recognize it. But do you not remember how, last summer, we watched the procession of ants climbing this very tree to get honey from a "herd" of aphids on the branches? Those bark-lice are still there, each hidden under a sort of scale, like a winter blanket; and it is these that the chickadees are pulling off and eating. It takes a great many of them to make a meal, and the birds must keep very busy. Perhaps that is one reason why they seem so happy. A busy person is usually a cheerful one.

When you meet a winter group of these merry tomtits it is well to wait quietly for a little while, since you are pretty sure to find others following them. There! do you hear that sharp tapping? Turn your head and you will see a small woodpecker with its checkered black and white coat, and a broad white stripe down the back, hewing away at the thick bark of that oak. He is tremendously in earnest, and let us hope he finds a good fat grub.

Gliding down the next tree-trunk comes something which for an instant we take for a mouse--it is so bluish and furtive; but it is a bird--a nuthatch--which has a straight slender bill almost like a woodpecker's, and which digs into the cracks and crannies for eggs and hiding grubs of small insects, now and then smashing a thin-shelled acorn for the wormy meal it contains, or tearing to pieces the fuzzy cocoon of a tussock-moth. It has an odd habit of working almost always head downward, and now and then lifts its head and squeaks out a sharp _nee-nee-nee_, as though it said "Never-mind-me. 'Tain't cold!"

Quite likely on the next tree a brown creeper--sedate brown little lady of a bird--is gliding about the trunk, very daintily picking and searching with her long slender and curving beak for similar hidden food. She is a dear little creature.

Even prettier are the kinglets that often form one of this little company of winter workers. They are the smallest of all American birds except the hummers, and are olive green with tiny crowns of gold and rubies, as one might say. They have the activity and nimbleness of the chickadees, and toward spring cheer us with a brilliant song. These lovely pygmies are cousins of the wrens; and one may sometimes see flitting about the brush a real wren, which in summer flies away to the far north, letting us hear for a few days in March, before he leaves, specimens of the exquisite song with which he will make the Canadian woods ring when next June he meets his mate and builds his nest among the great pines and spruces.

Most of our birds, you know, flee southward, when cold weather approaches, but some, like the crow, many birds of prey, as hawks and owls, some game-birds, such as Bob White and the grouse, several of the seed-eating sparrow tribe, and some others, such as the little fellows we have been watching, stay with us, because they find plenty of food. If we should go out every day of the winter we could make a long list of these by the time All Fools' day came around. To it might be added a goodly list of birds whose proper home is in Northern Canada, but which in midwinter come south to a country which is less snowy if not less cold. The snowbirds, with their satiny feet and ivory bills, dressed like gentlemen in lead-colored coats and white vests, to which you toss crumbs from the breakfast table every morning, are in this class. Doubtless we shall see others as we turn down the wooded lane that leads to the creek.

Here among these bushes is a good place to look for cocoons of moths and butterflies. One is pretty sure to see at once a few of those of the big Promethea moth folded within a large leaf, the stem of which is lashed by silk threads to its twig so that it will not fall or be blown away. Very likely on the same bush will hang a similar big cocoon, but this one fastened all along the under side of the twig, so that it is hammock-shaped. Search about among the heaped-up leaves beneath the bush, and you may find the cocoons of the great Polyphemus silkworm-moth and of that exquisite pale-green luna-moth which flits like a ghost to our lighted windows on summer nights.

But these are the giants of their race. Hundreds of smaller cocoons and chrysalids--papery, fuzzy, leathery, or naked and varnished to keep out the damp, may be discovered in the crevices of the old fence, upon and beneath the rough bark of trees, rolled up in leaves little and big, and buried in the ground, where the moles hunt for them when the ground is not frozen too hard, and the skunks dig them up.

How about the moles and the skunks? Well, the moles are by no means as active as in summer, though they move around somewhat under the frozen layer of top-soil, in search of the earthworms which have been driven deep down by the frost. As for the skunks, they, like the woodchucks, the chipmunks, and the red squirrels, are deeply sleeping in underground beds; but plenty of four-foots are wide awake. See how that gray squirrel is making the snow fly as he paws his way down to the nut he buried three months ago! Only the tip of the plume of his tail waves above the drift.

Do you see that double row of holes punched in the snow? Every country boy knows them as the track of a rabbit, and would tell you how fast the rabbit was going. But what embroidered on the glistening snow-sheet this lovely chain that extends wavily from this tree to that stone wall? A weasel. Little cares he for cold, in his white ermine coat; and many's the careless sparrow, and snugly tucked-in mouse that falls to his quick spring and sharp white teeth. The weasel's nearest cousin, the mink, is working for his living, too, these winter days, haunting the warm spring-holes in hope of catching eels or other fish. Perhaps we shall see some signs of his work along the creek.

And now we have come to the end of the last of our rambles. But don't think that we have seen nearly all that there is to be seen. If we had been able to spend a little more time in the fields, or the lane, or the wood, or on the banks of the stream, we should have noticed a great many more animals and birds and reptiles and insects, quite as curious and quite as interesting as any of those which we have met with. And if we had taken a dozen rambles together instead of only four, each time we should have found fresh creatures to look at, and fresh marvels to wonder at, and fresh beauties to admire. For wherever we go nature always has something new to show us; and the world is full of wonderful sights for every one who has eyes to see.

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.

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?