Within the Deep Part 4

1. Of what use are Sharks? 2. How does the Thresher Shark hunt its prey?

3. Give the names of several Dogfish and Rays. 4. What is the food of the Skate, and how is it obtained?

LESSON VIII

THE DANGERS OF THE DEEP

The "game" of hide-and-seek is played by most of the dwellers in the sea. Many of them are "hiders" and "seekers" by turn. That is to say, they are always seeking other creatures to devour, but must also be ready to hide from their own enemies.

_Eating and being eaten_--that is the life of the sea. The small and weak ones must hide, and their lives depend on their skill in hiding.

Perhaps we should not call it a "game," as it is not done for fun. But, though the sea is full of danger for some creatures, you must not think that they live in fear. There is no doubt that they enjoy their lives, each in its own way.

Many are the quaint dodges and tricks of the hiders and seekers in the sea. We can mention but a few in this lesson. Look at the Spider Crabs, and their trick of dressing up. They have hooks on their backs, which catch in the seaweed. Some of them even tear off weed with their pincers, and fix it on to these hooks, and succeed in looking like bundles of weed, and not a bit like living Crabs.

Then there are the fish which wear a coloured scaly coat. Many of them are not easily seen in the glinting water, as you know. Others are lazy; they lie on the bed of the sea, and wear a disguise which hides them from prowling foes. The Plaice and other flat-fish, as we noticed in Lesson 2, are coloured and marked like the sand and pebbles of their home; and they can even change colour to suit their background. They are wonderfully hidden, owing to this useful dodge. It is as if Mother Nature had given them the marvellous "cloak of invisibility," of which we read in fairy-tales.

Shrimps and young Crabs wear a coat of sand-colour or weed-colour. Our soldiers, for much the same reason, wear suits of _khaki_.

Another common hide-and-seek trick is to look like nothing at all. That sounds difficult, but it is a favourite dodge in the sea. If a number of very young Herrings or Eels were placed in a gla.s.s tank of sea-water, you would have a hard task to find them. You can look _at_ them, and yet not see them. They are transparent--you look through them as if they were water or gla.s.s. You can imagine how well hidden they are in the open sea.

It is well to be able to hide, when all around you are enemies who look on you as good food. But there is another way, and that is to wear armour. Then you can frighten your enemy, or at least prevent him from eating you. Some fish, like the Trunk Fish, (p. 52, No. 6), are covered with bony plates, jointed together like armour. Spines and p.r.i.c.kles are a commoner defence.

The little Stickleback of our ponds wears sharp spines, and knows well how to use them. Even the terrible Pike will not swallow such a dangerous mouthful unless driven by hunger.

Sea-fish are the most hunted of all living things. From the day they leave the egg, enemies lurk on all sides to gobble them up. The weak ones are eaten, and none of them has the chance to die of old age! So we find a defence of spines and p.r.i.c.kles worn by many sea-fish. Spines on the fins are the commonest, and no doubt help to keep away enemies; but some fish go one better than that, and wear a complete suit of spines.

The Porcupine-fish, as his name tells us, is one of these. He is a small fish, living in warm seas. No doubt he has many enemies, eager to meet him and eat him. But, when they see this little fish puff out his sides like a balloon, and when pointed spines rise up all over the balloon, they think better of it! They leave him alone; and the Porcupine-fish goes back to his usual shape, the spines lying flat until wanted again.

He is sometimes called the Sea-hedgehog or Urchin-fish, and well deserves his name.

Many of the Skates or Rays wear terrible spikes. The Starry Ray (p. 52, No. 7) is not easy to handle, dead or alive, for he has spines all over his body. The Thornback is another ugly fellow of this family, having spines on his back and a double row of them down his tail. Fishermen are careful to avoid the lash of this armed tail. The Sting Ray shows us still another weapon. At the end of its long tail it has a horrible, jagged three-inch spike. As this fish likes to bury itself in wet sand, bathers sometimes tread on it. In a flash the tail whips round! A poisonous slime covers the spike, causing great pain to the unlucky bather.

Several poisonous fish are common near our coast. You may have seen the one called the Great Weaver, also its small cousin, the Sting Fish. The Weaver is dreaded by fishermen; for the spines on its back fin, as well as the one on its gill-cover, cause poisoned wounds. They are grooved, to hold a very poisonous slime.

Some fish have the power to kill their prey, and stun their enemies, at a distance! Instead of a spiny defence, they are _armed with electricity!_ The best-known sea-fish of this sort is the Electric Ray, also called the Cramp Fish or Torpedo (_see_ p. 48). It is a clumsy fish about a yard long, and very ugly. Being too slow to catch its swift prey in fair chase, it stuns them with an electric shock, and then eats them.

The electric power comes from the body of the Ray; if it wishes it can send a deadly shock through any fish which ventures near. Without chance of escape, it is at once stunned, and falls helpless.

We come now to some formidable dangers of the deep--big strong fish, so well armed that they roam the seas without fear. On page 52 you see a picture (No. 2) of the Saw-fish, one of the Shark family. It is a large fish, and carries a big saw on its head, with which it stabs sideways at its prey.

Imagine, if you can, a Shark about fifteen feet long and weighing a ton or so. Now suppose the top jaw of this monster to be drawn out into a hard, flat blade six feet in length. Then suppose there are sharp ivory teeth, one inch apart, fixed on each side the blade, and you have an idea of the Saw-fish. This strange Shark is said to be as strong as it is fierce. It kills its prey by tearing them open with side blows from its sharp, two-edged saw. Its big mouth is fitted with a great many rows of needle-like teeth.

The Sword-fish wears a different weapon--a lance instead of a saw. He is not a Shark, but a cousin of the beautiful Mackerel. This warrior of the deep is more dreaded than the Saw-fish, and braver than any Shark. His speed in the water is marvellous; it makes him safe from attack. He carries in front of him a terrible weapon, and all sea-creatures hasten from his path as fast as they can.

You may have seen the Sword-fish in a museum. There is a fine one in the London Natural History Museum, where there is also a "sword" from one of these fish, driven eighteen inches into the solid oak of a s.h.i.+p. The Sword-fish never thinks twice about attacking, no matter if his enemy is ten or twenty times as large as himself. He sees a Whale, and, like a flash, hurls himself at it, stabbing his sword as deep as it will go into the Whale's side. With a twist of his body the sword is wrenched free, only to be driven savagely in again.

EXERCISES

1. Mention three ways in which sea-creatures try to escape their enemies. 2. How do the Sting-fish and Sting Ray defend themselves? 3.

What is the Saw-fish like? 4. How does the Sword-fish attack its prey?

LESSON IX

THE FISH OF OUR ROCK-POOLS

The pools left by the falling tide have many an interesting thing to show us. There are living creatures in plenty, besides the pretty weeds, sh.e.l.ls, and other objects. Shrimps, Prawns and Crabs abound in the rock-pools and shallows, with anemones and sh.e.l.lfish of all kinds. In the rock-pools we shall also find the interesting little fish whose story we glance at in this lesson. Of course there are baby flat-fish, and large fish too, along the sh.o.r.e. But these are only visitors. The real rock-pool fish are those which live their lives there.

Some of them are tiny things, two or three inches long. With quick movements like Shrimps they dart away as you approach. They have a way of hiding under weeds and rocks, being very clever at "hide-and-seek,"

and knowing all the dodges. But, by using a net, you will soon capture a few of them. Then you can put them in a small pool and examine them; or even keep them in an aquarium, giving them clean sea-water, seaweed, and the small shrimps on which they feed.

[Ill.u.s.tration: PIPE-FISH AND FLUTE MOUTH]

In our lesson on fish-nurseries we saw how the Sea-stickleback, Sand Goby and Pipe-fish cared for their eggs or young ones. These three fish are often to be found by the sh.o.r.e. As you look into the clear and still waters of a pool you may see a Pipe-fish getting its dinner. This funny creature looks more like a pencil swimming than a fish. It may be a foot in length, but its body is no thicker than a pipe-stem!

[Ill.u.s.tration: FISHES (No. 2).

1. John Dory.

2. Rock Cod.

3. Sand Eel.

4. Small Pipe Fish.

5. Cuckoo-Wra.s.se.

6. Angler.

7. Whiting.

8. Gattorngine.

9. Sapphirnal Gurnard.

10. Three-bearded Rockling.

11. Red Gurnard.

12. Pipe Fish.

13. Ba.s.s.

14. Red Mullet.

15. Turbot.]

It has very long jaws. They are quite useless, however, being fastened together! At their tip is an opening, though a very small one, and that is the mouth of the Pipe-fish. Of course, with such a mouth, the fish cannot bite its prey, and so has to suck in small creatures and swallow them. Its method of hunting them is strange. It stands on its head, as it were, takes in a mouthful of water, and spurts it out at the sandy bed of the sea. This stirs up the small living things, which are at once swallowed by the Pipe-fish.

We have already seen how the male Pipe-fish carries his eggs in his "pocket." Another curious thing is his suit of armour. Instead of scales, he has hard plates all over his body. Very often you may see young Pipe-fish among Sprats and "Whitebait" in the fishmonger's shop.

Most of the little sh.o.r.e-fish are either Gobies or Blennies. No doubt they have to avoid the sharp eyes of Gulls and Cormorants, for they are very anxious not to be seen. Some of these rock-pool fish do not mind being out of water for hours at a time. In every way Nature has fitted them for their life between sea and sh.o.r.e. They have cousins in warmer seas which love to come ash.o.r.e at times. This is how a traveller describes one of these foreign Gobies:--

"Though they are fish, and breathe by gills, they have a pa.s.sion for the land, and during the daytime may always be seen ash.o.r.e, especially where the coast is muddy. They bask in the sun, and hunt for food, raising themselves on their fleshy fins.... When pursued, they take great springs, using their tails and fins for the purpose; and if they cannot escape into the sea, they will dive down the burrow of a land-crab, or dash into a bunch of mangrove-roots." They are very wary, having eyes like swivels, to turn in all directions.

[Ill.u.s.tration: A b.u.t.tERFLY BLENNY]

The Spotted Goby, as we have already noticed, makes a nest under a sh.e.l.l, and guards it until the eggs hatch. Two other Gobies are quite common in the pools of our south coast--the One-spot Goby and the Two-spot Goby. The back fin has the one spot, or two spots, from which they get their name. Though they are such mites, they have sharp teeth, as you may already know if you have caught them with your fingers!

These lively little fellows are not very easy to catch! They have a cunning way of hiding amid sand and rock, and are coloured to suit such places. One strange thing about the Gobies is their trick of anchoring themselves to a stone.

You may wonder what kind of anchor they can use. It is a simple matter, however. The fins on the stomach are pressed together to form a little disc. This acts as a strong sucker, much like that of the Sucking Fish (p. 43). If the Goby wishes to stay still in one place, it presses its sucker to a stone; then it cannot be washed away by the ever-moving water.