CHAPTER XXXI

SALT-WATER FISHES

We now come to the fishes of the sea; and at the head of these we may place the sharks.

These savage and voracious creatures are found in all oceans, the larger ones wandering very widely, while the smaller ones are restricted to limited parts of the sea. Among the latter are the various small sharks called dogfish, from eighteen inches to six feet long, found on both sides of the North Atlantic. Though small, and harmless to man, the dogfish really is a shark, and for its size is very formidable, being able easily to fight and kill fishes quite as large as itself.

It is called the dogfish because it follows shoals of fish in the water, just as a wild dog will follow the animals on which it preys upon dry land.

When you are staying at the seaside you may sometimes find the dead body of a dogfish lying on the beach, where it has been flung by a very high wave. And you will notice how coarse and rough its skin is. This skin is often used for covering the handles of swords, as it gives such an excellent grip; and also for putting on the sides of match-boxes instead of sandpaper.

But even if you do not find the dogfish itself lying on the beach, you may often find its eggs, which are very curious little objects. They are something like oblong horny purses, of a yellowish-brown color, with a long twisted appendage at each corner, very much like the tendrils of a vine. By means of these the egg is anchored down to the weeds at the bottom of the sea, and they hold so firmly that they are hardly ever torn away, except during a violent storm.

At each end of this singular egg is a narrow slit, through which water can pass to the gills of the little fish which is lying inside it. And one end of the egg is made in such a manner that when the fish is ready to hatch it can easily push its way out.

THE BLUE SHARK

A much larger and more dangerous fish, which often visits northern seas, is the blue shark, which sometimes grows to a length of fifteen or sixteen feet. It does not often attack human beings, however, but is very destructive in our fisheries, snatching away fishes which have been hooked, and even swimming along the outside of the nets as they are being drawn in, and biting great holes through them, in order to get at the pilchards or herrings within. So the fishermen always kill a blue shark if they have the chance of doing so, and sometimes destroy eight or ten in a single day.

But it is not very easily caught, for if it is hooked it will often bite the line asunder, and if it cannot do this will roll round and round in the water coiling the line round its body, when it will snap with a sudden jerk. Even when it is caught, the blue shark is not killed without much difficulty, for it thrashes its great powerful tail about in such a manner that it cannot be approached without danger. So the first thing that the fishermen always try to do when it is captured is to chop off its tail with an ax.

The color of this shark is slaty blue above and white beneath.

THE WHITE SHARK

Even larger and more dangerous still, the great white shark, or Rondeleti's shark, is one of the most formidable creatures that roam the seas. It often grows to a length of thirty-five or even forty feet, and weighs ten or twelve tons, while one snap of its huge jaws will shear off a man's legs or cut his body in two.

This enormous fish is found in all the warmer parts of the sea; and in general sharks, and especially the large ones, belong to the tropical rather than to the colder seas.

THE HAMMERHEAD

A huge and much-to-be-dreaded creature, of curious appearance, this fish has its head formed just like that of a hammer, the eyes being placed at each end of the projecting lobes. It grows to a length of fifteen or sixteen feet, and is very fierce and savage, attacking human beings without the least hesitation. It is nearly always found in the tropical seas, but has been several times captured off the coasts of New England.

THE THRESHER

Growing to a length of ten or twelve feet, the thresher is a remarkable shark. It is common in the Mediterranean Sea and the Atlantic Ocean. It feeds chiefly upon herrings, darting into the midst of a shoal and snapping them up in hundreds.

What it is specially famous for, however, is its habit of attacking whales. For this purpose several threshers will unite together, leap up into the air, and strike tremendous blows with their long tails upon the whale's body as they fall back into the sea. This naturally terrifies the whale, and he dives under water in order to escape from his tormentors. Knowing that he must very soon rise again, however, they wait for his reappearance, and then attack him again in the same way. This happens again and again, until he is quite worn out by his exertions, and by the impossibility of remaining long enough at the surface to breathe properly. Then if any swordfishes happen to be in the neighborhood, they come and attack him too, driving their long swords deep into his body. Before long the whale is dead, and both threshers and swordfishes are tearing great strips of flesh from the carcass and greedily devouring them.

SAW-FISHES

Next to the sharks come the saw-fishes, which have the upper jaw drawn out into the form of a long, narrow beak, set on either side with a row of large, pointed teeth. So it really looks very much indeed like a saw. The fish uses this curious weapon by dashing into the midst of a shoal of smaller fishes and striking them right and left with its saw. In this way it is sure to disable a good many, which it then swallows leisurely one after the other.

Saw-fishes are found in all the warmer seas, and sometimes grow to a length of fifteen or twenty feet.

RAYS

The rays have broad flattened bodies, and very long and slender tails. In consequence of this structure they cannot swim by means of their tails, as nearly all other fishes do, but travel slowly through the water by waving their side fins, after the manner of soles and flounders.

One of the best known of these fishes is the skate, which when fully grown sometimes measures as much as six feet in length from the snout to the tip of the tail, and five feet in width of body. As it cannot swim fast enough to overtake other fishes, it preys chiefly upon crabs, lobsters, and shell-bearing mollusks, which it finds on the bottom and is able easily to crunch up, shells and all.

The eggs of this fish may be found in great numbers on the sea-shore. They are very much like those of the dogfish, but are nearly black in color, and instead of a long twisted tendril at each corner, they only have a blunt projection about an inch long. They remind one, in fact, of a hand-barrow, and consequently the fishermen often call them "skate-barrows."

In color, the skate is grayish brown above and grayish white beneath.

Another very curious ray is the torpedo, which is an electric fish, having a kind of electric battery inside its body, from which a very powerful shock can be discharged at will. This battery, in appearance, is something like a honeycomb, consisting of a number of six-sided columns, which run from the skin of the back to that of the lower surface of the body. Each of these columns is divided into a number of cells, or chambers, by thin walls of membrane; and each cell contains a liquid which seems to consist chiefly of salt and water.

The electricity produced and stored up in these organs seems to be discharged along four great nerves, which run from the battery up to the brain. The shock is sufficiently strong to kill a duck; and not only has an electric bell been rung by it, but an electric spark has been actually obtained. And when five persons held one another's hands, and the person at each end laid his finger upon the torpedo, every one of the five persons felt the shock.

Even more formidable, though in quite a different way, is the sting-ray. At the base of its long whip-like tail this fish has a bony spine set with sharp teeth, like a saw; and its favorite mode of attack is to coil this tail round the body of its victim and then to drive the spine into his flesh, working it backward and forward in such a manner as to cause a very serious wound always followed by severe inflammation.

Some of the rays in the warmer seas grow to a very great size; indeed, a ray measuring over eighteen feet in length has more than once been captured. They are dangerous creatures to meddle with, for a fish of this size is quite strong enough to overturn a boat, while if a man were once seized by one of them, he would have very little chance of escape.

These huge creatures are generally known as devil-fish.

THE STURGEON

This fish belongs to quite a different group, which may be distinguished by two points. In the first place, its skeleton is made not of bone, but of gristle; and in the second place, five rows of shield-like bony plates run along the back and sides of the body, forming a kind of natural armor.

The sturgeon is often eight or nine feet long, and weighs three or four hundred pounds. It spends most of its life in the sea, but ascends the rivers in order to spawn, like the salmon. It is not so common as formerly in American waters, although sturgeon are taken in nearly all our larger rivers from time to time; but in some parts of Europe, and especially in Russia, it is very plentiful.

Caviare is made from the sturgeon's roe. The membranes which separate the eggs from one another are all removed, and the eggs are then salted and pressed into small barrels, being afterward eaten as a kind of preserve.

The best isinglass is made from the sturgeon's swimming-bladder, which has so much gelatine in it that, if a small quantity is dissolved in a hundred times as much boiling water, it will form a stiff jelly when it is cold.

The sturgeon's flesh is very good to eat, for it is not only well-flavored, but is so firm and solid that it is almost like beef.

In England the sturgeon is known as a "royal" fish, because, in days of old, when one of these fish was caught in an English river, it was always kept for the table of the king; and even now, if a sturgeon is captured in that part of the Thames which is under the control of the Lord Mayor of London, it belongs by right to the Crown.

THE BEAKED CHÆTODON

A great many fishes are very odd to look at, and this is one of the oddest. Imagine a fish with an almost circular flattened body, with five brown bands edged with white running round it, huge round eyes, enormous triangular fins both above and below the body, a broad tail, which looks as if it were tied in by a piece of ribbon at the base, and a mouth drawn out into a long slender beak! And this fish has a habit which is even odder still, for when it sees an insect sitting on a leaf which overhangs the margin of the sea, it takes careful aim, squirts a drop of water at it from out of its long beak, and nearly always succeeds in knocking it into the water below!

This fish lives in the Indian and Polynesian seas, and is sometimes kept as a pet by the Japanese, who amuse themselves by fastening a fly to the end of a piece of stick and holding it over the bowl in which the fish is living, in order to see it knocked off its perch by a pellet of water.

THE COD

Throughout the northern seas the cod is found, and in some parts it is taken in immense numbers. The largest and finest of all, which sometimes weigh more than one hundred pounds, come from the banks, or shallows in the sea, off the shores of Newfoundland, but very fine ones have been taken elsewhere; and extensive cod-fisheries are maintained in the North Pacific, near Alaska.

Cod are mostly captured by means of long lines, each about forty fathoms in length, to which a number of smaller lines are fastened at intervals. The hooks are placed on the side lines, and are generally baited with whelks, and then the long lines, or trawls, as the fishermen call them, are anchored in shallow parts of the sea where codfishes, halibut, and the like abound. Each boat carries about eight miles of these lines, with nearly five thousand hooks, so that the work of baiting, lowering, and raising them is very heavy indeed. The fishing takes place in the winter, and the boats are generally out in all weathers for several months at a time.

One would think that with so many boats engaged in cod-fishing, each with so many miles of line, nearly all the cod in the sea would soon be caught. But to offset this, a single cod in a single year will often lay eight or nine million eggs, so that notwithstanding the immense number of these fishes which are taken, they still seem as plentiful as ever.

FLATFISH

The so-called flatfishes, such as the sole, the plaice, the flounder, and the dab, form an interesting group. Although we call them "flat," we ought really to call them "thin," because what we always consider as the back of a sole is really one of its sides, and what seems to be the lower surface is the other side.

The explanation is this: when these fishes are quite small, they swim upright in the water, just as other fishes do, and drive themselves along by means of their tails. But when they are about a month old a strong desire comes over them to go and lie down on the mud at the bottom of the sea, and then three remarkable things happen.

First their color changes. Up till now, both sides of their bodies have been nearly white. But if a white fish were to lie down on dark-brown mud, of course it would very easily be seen, and most likely would very soon be devoured by one of its many enemies. So as soon as the little fish lies down at the bottom of the water its upper surface begins to grow darker, and before very long it exactly resembles the hue of the surrounding mud. Or if the fish should lie upon sand, as the plaice does, then its upper surface becomes colored like the sand. So as long as it keeps still its enemies may pass quite close to it without noticing it.

The next thing that happens is that the little fish changes its way of swimming. Hitherto it has driven itself through the water by means of its tail; now it uses what were formerly its upper and lower fins, but have now been turned into side fins. And by a very graceful waving movement of these fins it winds its way, as it were, through the water.

But the third change is the strangest of the three. One of the eyes would now seem to be useless, since it is on the lower surface of the head as the fish lies on the sea-bottom, and would be completely buried in the mud. But as soon as the fish goes and lies down at the bottom of the sea, this eye actually begins to travel along the lower surface of the head, till at last it works its way round and settles down by the side of the other!

If you look at the flounders the next time you pass by a fish-market, you will observe that both eyes are placed quite close together above the same corner of the mouth. That is because the lower eye traveled round the head till it found a resting-place by the side of the other.

In habits, all these fishes are very much alike. They are found in almost all seas, except those of the polar regions, and in most parts of the world are exceedingly plentiful, and everywhere form a cheap and excellent food.

THE SWORDFISH

A very odd-looking creature is this. It abounds in the Atlantic and also in the Mediterranean. Its chase affords one of the finest summer sports to be enjoyed along the south coast of New England, where it is taken by spearing from swift sailboats.

In this fish the upper jaw, which has hardly any teeth in it, is drawn out into a long, slender, pointed beak. With this "sword" the fish impales its victims, which are often of considerable size; but how it gets them off its beak again in order to eat them nobody seems to know.

This fish sometimes drives its way through the water with such tremendous force that it has been known to pierce the planking of a boat with its sword, which it had to snap short off in order to release itself.

In the Natural History Museum at South Kensington, London, there is part of a beam taken from the hull of a ship, into which one of these fishes had driven its sword to a depth of twenty-two inches.

MACKEREL

One of the best known of all the salt-water fishes is the mackerel. This fish lives in enormous shoals, which are always traveling from place to place, and visit the same parts of our coasts at about the same season in every year. Sometimes they are caught in most extraordinary numbers, so that they can be purchased at very small prices. In some cases, indeed, the catch has been so heavy that it has been found quite impossible to draw in the nets, which had to be allowed to sink to the bottom with the fishes still in them.

These nets are generally made with rather large meshes, not quite wide enough to allow the fishes to swim through. When the mackerel are caught they try to force their way through the meshes, but find that they cannot do so. They then attempt to back out. In doing this, however, the thin twine of which the net is made is almost sure to become entangled with their gill-covers, so that they are held prisoners until the net is lifted from the water.

When fully grown the mackerel is about sixteen inches long, and weighs perhaps two pounds.

SUCKING-FISHES

Of the sucking-fishes, or remoras, there are about a dozen different kinds, distinguished by the odd sucker-like disk on the upper part of the head, by means of which they can attach themselves firmly to any object to which they wish to cling. They often fasten themselves in this manner to the hulls of ships, and also to the bodies of sharks and the shells of turtles, and so are carried for long distances without any exertion of their own.

So firmly do these odd little fishes cling, that it is most difficult to remove them without injuring them, and the sharks and turtles have no means of forcing them to loose their hold.

It is a very odd fact that the coloring of the sucking-fishes is just the opposite of that which we find in almost all other fishes. Instead of the upper surface being dark it is light, and instead of the lower surface being light it is dark. But when one of these fishes is clinging to a shark it is the lower surface which is seen, not the upper one; for _that_ is pressed against the body of the shark; and in order to prevent its enemies from seeing and eating it, the lower parts of its body are colored just like the skin of the shark.

WEEVERS

Strange little fishes are the weevers, two kinds of which are found on the coast of Europe.

Both are highly poisonous, a prick from the spines of the upper fin or the gill-cover being almost as serious as the sting of a scorpion. The poison lies in a deep double groove on each spine, and as the fishes have a habit of burying themselves in the sand at the bottom of shallow water, with only just the sharp spines projecting, they are rather apt to be trodden upon by bathers.

Accordingly, when a fisherman catches a weever-fish he always cuts off its back fin and the spines of its gill-covers at once; while in France and Spain he is compelled to do so by law.

THE ANGLER

The angler, or all-mouth, is the name of a hideous creature--about five feet long when fully grown--with a huge mouth, a great broad body shaped very much like that of a seal, two big round eyes which look almost straight up into the water above, and a row of long, slender spines on the back instead of the usual fins. The first of these spines has a broad, tufted, glittering tip, used for a most singular purpose.

It is a creature of prey, feeding entirely upon other fishes; and it has a most enormous appetite, which is hardly ever satisfied. But, at the same time, it is so slow in its movements that if it were to try to chase its victims it would never get anything to eat. It seems to know perfectly well, however, that fishes are very inquisitive creatures, and that they are always greatly attracted by any object that glitters. So when it feels hungry it lies down at the bottom of the sea, stirs the mud gently up with its side fins, so as to conceal itself from view, and dangles the glittering spine up and down in front of its open mouth. Before very long some passing fish is sure to come swimming up to see what this strange object can possibly be; and then the angler just gives one snap with its great jaws, and that fish is seen no more.

Just to show you how successful it is in its fishing, we may tell you that from the body of a single angler no less than seventy-five herrings have been taken, while another had swallowed twenty-five flounders and a John-dory!

There is another kind of angler which lives down at the bottom of the deep sea, where it is always perfectly dark. There, of course, a glittering spine would be useless, for the other fishes would not be able to see it. So this angler has a spine which shines at the tip like a firefly, so that it can be seen from a considerable distance as the fish dangles it up and down!

GURNARDS

These, too, are remarkable fishes, having square heads, which look ever so much too big for their bodies, and the first three rays of their pectoral or breast fins made like fingers. These breast-fins are used like fingers, too, for they serve as organs of touch, while the fish also walks with them along the sand at the bottom of the sea.

At least forty different kinds of gurnards have been discovered, but nearly all dwell along foreign coasts. The handsomest of these, perhaps, is the red gurnard, which grows to a length of twelve or fourteen inches, and is bright red above and silvery white below.

FLYING FISHES

Though objects of never-ending interest to every one who journeys through the warmer seas, flying fishes do not really fly. They merely skim for long distances through the air, just as the flying squirrel and the flying dragon do; but instead of having a broad parachute-like membrane to buoy them up, they are supported in the air by the pectoral or breast fins, which are very large. These fins do not beat the air, like the wings of a bird. They merely support the body. And the power of the so-called flight is due to a stroke of the tail just as the fish leaves the water.

The reason why these fishes take their long leaps through the air appears to be that they are much persecuted by other fishes, bigger and stronger than themselves, and that they know quite well that they will be overtaken if they remain in the water. They do not usually rise to a height of more than a few feet above the surface, and the greatest distance to which they can travel without falling back into the water seems to be about two hundred yards. Whether they can alter the direction of their course while they are in the air is uncertain. Some observers say that they can, while others declare that they cannot. But it is possible that they may sometimes do so by just touching the crest of a wave with their tails.

Flying fishes are found in all the warmer parts of the sea, and are very common in the Mediterranean and the West Indies.

THE HERRING

Like the mackerel, the herring is one of those fishes which live in vast shoals and are of great value as a cheap and nutritious food. These shoals consist of millions upon millions of fishes, and when they are swimming near the surface of the sea their presence can generally be detected by the numbers of sea-birds which follow them and devour them in countless thousands. Whales, too, often follow the shoal for days together, and sharks and many other big fishes do the same. Yet nothing seems to lessen their numbers.

These shoals generally appear in the same parts of the sea, year after year, at the same season. But sometimes the herring will desert their favorite haunts without any apparent cause. During spring and early summer they remain in deep water; but in June and July they come in nearer the coast in order to spawn.

GOBIES

There are still several very curious and interesting fishes about which we should like to tell you; and among these are the gobies. Many different kinds of these odd little creatures are found in different parts of the world other than North America; but perhaps the best known of all is the black goby, which is very common off British coasts. You can often catch it by fishing with a small net in the pools which are left among the rocks as the tide goes out. And if you look into these pools from above, you may often see it clinging to the rocks round the margin. It does this by means of the fins on the lower part of its body, which are made in such a manner that when they are placed side by side together they form a kind of sucker. And if you keep the fish in an aquarium, it has an odd way of suddenly darting at the side of the tank, clinging to it with its fins, and staring at you through the glass.

Some of the gobies make nests in which to bring up their little ones, just as the sticklebacks do. One of them, the spotted goby, which is found rather commonly in the lower reaches of the Thames, nearly always takes one of the shells of a cockle for this purpose. First it turns the shell upside down; then it scoops out the sand from beneath it, and smears the surface of the hollow with slime from its own body; and then it piles loose sand over the shell, so as to keep it in position. Lastly, it makes a little tunnel by which to enter the nest from outside. This work is always performed by the male. When the nest is quite finished the female comes and lays her eggs in it, after which the male keeps guard over them until they hatch, about eight or nine days later.

MUD-SKIPPERS

More curious still are these fishes, which are found on the coasts of the tropical seas, and often make their way for some little distance up the estuaries of rivers. They have singular eyes, which are set on the upper surface of the head, and can be poked out to some little distance and drawn back again in the oddest way. And besides that, these eyes have eyelids. Then the lower fins are made just like those of the gobies, but with an even greater power of clinging, so that the fish can climb by means of them. Often these queer little creatures leave the sea altogether and skip about on the muddy shore, or even climb up the trunks of the trees which overhang the water. Sometimes they will rest for quite a long time on the spreading roots, snapping at the flies and other small insects which come within reach. They do not look like fishes at all as they do so. They look much more like rather big tadpoles. And if they are suddenly startled they go hopping and skipping back into the water, not diving at once, but leaping along over the surface, very much as a flat stone does when thrown sideways from the hand.

Some of these fishes were kept for some time at the London Zoo, and when they were out of the water they had an odd way of lying at full length and raising their heads and the front part of their bodies by means of their lower fins, so that they reminded one very much of a man with his elbows resting upon the table.

PIPE-FISHES

The pipe-fish has its mouth drawn out into a very long snout, so that it forms a kind of tube; the body is sixteen or eighteen inches long, yet scarcely stouter than an ordinary drawing-pencil; and the only fin, besides a small one on the back, is a tiny one at the very tip of the tail. Besides this, the whole head and body are covered with bony plates, which form a kind of coat of mail. And the fish is even odder in habits than in appearance, for when the eggs are laid they are put into a pouch in the lower part of the body of the male, and are kept there until they hatch! It is even said that after the little ones are hatched and are able to swim about in the water, they will return into the pouch of the parent in moments of danger, just as young kangaroos will into that of their mother. But this does not seem to have been proved.

Pipe-fishes are not uncommon on our coasts, and you may often find them in the pools among the rocks when the tide is out. They swim half erect in the water, and if you watch them carefully you may see them poking their long snout-like mouths in among the seaweeds in search of food, standing on their heads among the eel-grass, in which position they are hard to see, or blowing furrows in the sand at the bottom of the pool in order to turn out any small creatures which may be lying hidden in it.

THE SEA-HORSE

Closely related to the pipe-fish is the sea-horse, which reminds one of the knight in a set of chessmen. It has a long and slender tail, which is prehensile, like that of a spider-monkey; and by means of this organ the fish anchors itself firmly down to the stems of seaweeds, or to any small object which may be floating on the surface of the water.

The eyes of this fish can be moved independently of each other, like those of a chameleon; and if you keep one of these creatures in a bowl of sea-water and watch it for a few minutes, you will find it hard to believe that it is not purposely "making faces" at you!

The male sea-horse, like the male pipe-fish, has a pouch underneath his body, in which the eggs are placed as soon as they are laid, and are kept until they hatch.

The sea-horse swims by means of a single fin on its back, which acts on the water very much like the screw of a steamboat. Just at the back of its head are two more fins, and when these are thrown forward they look like the ears of a horse, increasing the queer resemblance of its long head to that of a pony.

Sea-horses are found in most of the warmer seas, and in summer float north with the Gulf Stream, so that they are frequently seen near New England.

CONGERS

Just as there are eels which live in the fresh water, so there are eels which live in the sea. These are known as congers, and very often they grow to a great size. A conger eight feet long is by no means uncommon; and a fish of this length will weigh at least one hundred pounds.

Congers generally live in rather shallow water off a rocky coast, where there are plenty of nooks and crevices in which they can hide during the daytime. It is rather curious to find that those which live in muddy places are nearly always dark brown or black in color, while those which lie upon sand are light-colored, and sometimes almost white.

These eels are generally caught by means of long lines, which are set at intervals with short "snoods" just like those which are used in catching cod. The hooks are generally baited with pilchards, or else with pieces of the long arms of cuttles. When the congers are lifted on board the scene is usually an exciting one, for they are very powerful and active, and go twisting and writhing about in the most extraordinary manner, slapping vigorously on all sides with their long tails. These tails, too, to some extent, are prehensile, and sometimes the fishes will seize the gunwale of the boat, and then, with a sudden effort, pull themselves over the side and drop back into the water. As soon as they are lifted on board, the fishermen always try to stun them by a heavy blow on the lower side of the body, after which, of course, they can be easily killed.

Congers feed, as a rule, upon mollusks, which we wrongly call shell-fish, devouring them shells and all. They will also eat small fishes, however, and sometimes they are cannibals; for inside the body of one of these fishes a young conger was found that was three feet in length!

AMPHIOXUS, OR LANCELET

In this we see a creature so curiously formed that a good many naturalists have doubted whether it ought to be ranked among the fishes at all. For in appearance it is much more like a slug; and it has no skull, and no brain, and no bones, and no eyes, and no gills, and no heart! It has a fin running along its back, however, and although it has no spine, it possesses a spinal cord. So it is considered as the very lowest of all the fishes, and as a kind of link between the animals with bones and those without them.

This strange little creature is about two inches and a half long when fully grown, and is so transparent that one can almost see through its body. It is very active, and can wriggle and twist about in the water, or on the mud, with considerable speed. It spends most of its life concealed under large stones, or lying almost buried in the muddy sand at the bottom of the sea. And it seems to feed upon those minute atoms of decaying animal and vegetable matter which are always floating about in countless millions in the waters of the sea.

INVERTEBRATES