The Animal World, A Book of Natural History Part 45

The little fishes are now known as smolts, and, like their parents; they make their way down the river and pa.s.s into the sea. There they remain until the autumn, when they ascend the river again. By this time they have grown considerably, weighing perhaps five or six pounds, and are called grilse. And it is not until they have visited the sea again in the following year that they are termed salmon.

When salmon are ascending a river and come to a waterfall, they climb it by leaping into the air and so springing into the stream above the fall, trying over and over again until they succeed. When the fall is too high to be climbed in this way, the owners of the river often make a kind of water staircase by the side of it, so that the fishes can leap up one stair at a time. This is called a salmon-ladder.

NORTH PACIFIC SALMON

Now this description would not at all fit the case of the salmon which live in the North Pacific and ascend the rivers of California, British Columbia, and Alaska, and of Siberia and j.a.pan on the other side of the ocean. These are the salmon which supply the whole country, and many other countries, with their pink flesh, boiled, and sealed in cans, so that it may be sent long distances and kept many months without spoiling. Every spring and summer, at different times according to the locality and the species--there are five kinds of importance, caught for the trade--vast numbers of them enter the mouths of the rivers and begin to make their way up-stream in their effort to reach the shallow head waters of each river, and of every one of its tributaries. It is at this time that they are caught by spearing, netting, and various contrivances; but laws prevent any general obstruction which would altogether stop the advance of the host, so that while tens of thousands are taken great numbers escape and pa.s.s on, as it is necessary they should do in order to lay eggs and so keep up the race.

This takes place far up at the heads of the streams in the foothills of the mountains; and having deposited the sp.a.w.n, late in summer, the spent fish begin to drift down stream again. But all this time they have been eating nothing, they are worn with the long struggle against the rapids, often wounded by sharp rocks, and are good for nothing to catch or eat.

In fact, so f.a.gged out and weak are they that all of them die before any reach the mouth of the river. It is a strange fact that of all the vast host of salmon which each summer climb the rivers not a single one gets back to the sea.

A year later, however, the young hatched from the eggs which were left behind them at the heads of the streams swim down the rivers and enter the ocean. There they remain, probably not very far from land, for two or three years, feeding and growing until they are of full size and strength; and each season a cla.s.s of them, having reached the right age and condition to sp.a.w.n, force their way up to the sp.a.w.ning-grounds, to leave their eggs and then die, as did their parents before them.

EELS

The only other fresh-water fishes which we can notice are the eels, which look more like snakes than fishes, for they have long slender bodies, with a pair of tiny fins just behind the head, a long one running along the back and tail, like a crest, and another, equally long, under the body. And they are clothed with a smooth, slimy skin instead of with scales.

These curious creatures live in ponds and even in ditches as well as in rivers, and are very plentiful in all parts of the northern hemisphere.

During the daytime, although they will sometimes bask at the surface in the warm suns.h.i.+ne, they generally lie buried in the mud at the bottom of the water, coming out soon after sunset to feed. And when the weather is damp, so that their gills are kept moist as they wriggle through the herbage, they will often leave the water and travel for some little distance overland.

They frequently do this when they are traveling toward the sea.

For it is a strange fact that, although they are fresh-water fishes, eels both begin and end their lives in the sea.

In the first place, the eggs are laid in the sea--generally quite close to the mouth of a river. When the little elvers, as the young eels are called, hatch out, they make their way up the river in immense shoals.

In the English river Severn, for instance, several tons of elvers are often caught in a single day; and about thirty million elvers go to the ton! After being pressed into cakes and fried, these little creatures are used for food; but they are so rich that one cannot eat very many at once.

When they have traveled far enough up the river, most of the elvers which have escaped capture make their way to different streams and pools and ditches, and there remain until their growth is completed. They then begin to journey back to the sea, and when they reach it they lay eggs in their turn. After this, apparently, they die.

In the rivers of South America a most wonderful eel is found which has the power of killing its victims by means of an electric shock, wherefore it is called the electric eel. The electricity is produced and stored up in two large organs inside the body, but how it is discharged n.o.body knows. If the fish is touched it merely gives a slight shudder.

But the shock is so severe that quite a large fish can be killed by it, while a man's arm would be numbed for a moment right up to the shoulder.

LAMPREYS

The lamprey, which is found plentifully in many northern rivers, is very much like an eel in appearance. But it has no side fins, and instead of possessing jaws, it has a round mouth used for sucking, and resembling that of a leech; and on either side of its neck it has a row of seven round holes, through which water pa.s.ses to the breathing-organs.

Lampreys seem to spend the greater part of their lives in the sea, but always come up the rivers to sp.a.w.n. They lay their eggs in a hollow in the bed of the stream, which they make by dragging away stone after stone till the hole is sufficiently deep. Very often a large number of lampreys combine for this purpose, and make quite a big hole, in which they all lay their eggs together.

The length of the lamprey is generally from fifteen to eighteen inches, and its color is olive brown.

CHAPTER x.x.xI

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 coa.r.s.e 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 h.o.r.n.y 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 anch.o.r.ed 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 pa.s.s 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, s.n.a.t.c.hing 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 carca.s.s 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 das.h.i.+ng 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.