We do not eat these little Crabs, but other Crabs do, and so do anemones, gulls, and other hungry creatures; and they themselves hunt sand-hoppers, and eat anything they can find or steal. So they grow bigger; and then, like the boy who grows quickly, the Crab finds his shelly suit a size too small for him!
Now look at his suit. It is a hard coat, a complete suit of armour to protect his soft body. Our picture shows the Lobster, the Crab's cousin. The Shrimp and Prawn and Lobster are relations of the Crab; thesecrustaceans, as they are called, are all cased up in a hardcrust, which will not stretch the slightest little bit. But the Crab's bodymustgrow! What is he to do?
At first he starves himself, and so his body shrinks inside its old shell. He loosens himself as well as he can. Soon the shell breaks across, and the Crab struggles to get free. At last he backs out, and leaves his old suit for ever. It is a wonderful performance, for he has withdrawn even from the legs, claws, feelers, bristles, eye-stalks and eyes! The old shell is left quite whole--a perfect Crab, but with no Crab inside it!
Now the Crab, in his new suit, hides away. He knows that he is a soft, flabby creature at this time, and that other animals, even Mrs. Crab, would be glad to meet him--and eat him. While his covering is yet soft he grows quickly. When it is hard, he ventures out again, ready to quarrel and fight.
This change of shell happens often to young Crabs. Older ones change only once a year. All the different kinds of Crab begin life aslarvaeorzoeas, and cast their shells as we have seen.
Crabs can see and hear and smell; and they must also have a fine sense of touch. I was once watching a big Crab eating his dinner under a rocky ledge in a large glass tank. As he tore his food, some of the bits, no larger than crumbs, fell and settled on the rocks below. Then I saw that a smaller Crab, with long pincers, was hiding under a rock. As the crumbs fell, he reached out his pincers and picked them up, one by one. Each bit was gravely carried to his mouth, and tucked in, and then he reached out for another. Though I was very close to the Crab, I could hardly see the tiny scraps which he was able to pick up so easily.
One of the strangest Crabs is the Hermit. You would think that Nature had played a joke on him, for he has only half a suit of armour. His tail part is soft. He would have a bad time in the sea, but for a dodge he has learnt.
The baby Hermit takes the empty home of a periwinkle. As he grows he needs a larger house, and so leaves the tight shell and pops his tail into a bigger one, generally a whelk shell. If he meets with another Hermit there is a battle, one trying to steal the other's shell. Our coloured picture, page 35, shows some Hermits at war. Fighting, house-hunting, and moving house seem to be the Hermit's favourite pursuits. But, whatever he does, his first care is to protect that soft tail of his. His right claw is large and strong, so he uses it to close the door of his stolen home.
Sometimes he has a lodger who lives on the roof. This lodger, as you will notice in our coloured picture, is the sea anemone. The Hermit and his lodger seem to be good friends, at least they seem to like each other's company. There is no doubt that there are good reasons for this. We shall have more to say about this strange pair in our lesson on the sea anemones.
Another funny Crab is the Spider Crab. Its back is covered with reddish bristles, like so many hooks. These catch in the seaweed, and soon the Spider Crab is decorated with bits of weed. But that is not all. The artful Crab tears off other pieces of weed with its pincers, and attaches them to the hooks. It is another dodge, of course, to escape from enemies. The Lobster, whose picture you see, has a life-story much like that of the Crab. He, also, grows too big for his suit of armour, and casts it off in a wonderful manner, but only after a great deal of trouble. In his new suit he is very weak and soft--an easy prey to the first enemy to find him. He cannot defend himself then; he can only lie helplessly on his side, waiting for his coat to harden. He is so weak that his soft legs cannot bear the weight of his body.
Needless to say, the Lobster always finds a secure retreat before casting off his protecting coat of armour. A hole under a rock suits him well at that time. Strange to say, he seems to dislike his old clothes, and often crunches them to pieces or eats them up, or even pushes them under the sand or stones! Then he marches out like a proud warrior, knowing his strength, and the power of his great claws.
Lobsters are fond of fighting, and must be very disagreeable neighbours. They can swim along by using the little "swimmerets" under their bodies. Or, by rapidly bending down their powerful tails, Lobsters are able to shoot backwards through the water at a great pace. In our next lesson we shall find that Prawns are also able to paddle forwards or dart backwards in a similar way.
Lobsters, living and dead, are often on sale in the fishmonger's shop. Like the Crabs and Prawns, they are usually caught in traps or pots, baited with pieces of fish, and left among the rocks. The traps are of various shapes, some being like bee-hives made of cane or wicker; others are made of netting stretched over hoops, and more like a bird-cage in shape.
The Lobster smells the bait in the trap, and hastens to get to it by diving through the only entrance. Having enjoyed his meal he tries to swim away; but there is no escape, and there he must wait until the owner of the trap makes his usual "round" in the morning. Of course, there is a rope to every trap, and a cork to mark its position.
Then the Lobster finds himself taken carefully out of prison; his claws are tied to prevent him from fighting, and he goes to market with a lot of other Lobsters. There are many lobster fisheries along the rocky parts of our coast.
You will often see Lobsters with one very large claw, and one small. They are able to throw off a limb or two whenever they are frightened. Also they often lose a claw in the terrible fights of which they seem so fond. If one joint of a claw becomes injured the Lobster has no further use for it; he is wise, for his very life depends on his armour. So he throws it away, not at the wounded joint, but at the joint above.
After a time a slight swelling appears on the stump thus made; this gradually grows into a new limb. It may be smaller than the lost one, but it is perfect in detail. What a useful gift this must be to an animal like the Lobster, whose whole life is one terrible fight after another!
The baby Lobsters, like the baby Crabs, are quite unlike their parents. They swim about at the surface of the sea, and already they seize every chance of fighting and eating their small neighbours.
When about one inch in length they leave this infants' school, and join another at the bottom of the sea. Here they eat, fight, grow and change their coats, just as the young Crabs do. They are now like their parents. Sometimes they grow to be huge, and to weigh as much as ten-and-a-half pounds.
The mother Lobster carries as many as thirty thousand eggs under her body! Needless to say, a very, very few of this enormous family survive the dangers of the sea. The rule there is--"Eat and be eaten!".
EXERCISES
1. What is a Crab larva like?
2. Give the names of four crustaceans.
3. Why does the Crab have to change its shell?
4. Why does it hide away at that time?
5. Of what use are Shore Crabs?
6. How are Lobsters caught?
SHRIMPS, PRAWNS AND BARNACLES.
In nearly every shore-pool you may see Shrimps and Prawns darting out of sight, and, for every one you see, there are many more hidden away. These delicate, transparent, lively creatures are not much like the boiled Shrimps and Prawns of the fish-shop.
They are the prey of so many fish, crabs, and birds, that they have learnt to "make themselves scarce." Have you ever watched them in a glass tank, or aquarium? If so, you will know that it is not easy to see them. In the shore-pools it is harder still.
Some are swaying about in the still, clear water, moving their long feelers from side to side. Others have burrowed into the sand. In doing this, they raise a sandy cloud, which settles on them and hides them. To catch some, you must use a "shrimp-net," for they can dart across the pool like arrows.
Some are Shrimps, and some are Prawns; how can we tell the difference? When they are boiled the answer is easy. All the Shrimps turn brown and the Prawns red. (The red "Shrimps" are near relations of the Prawn.) To tell a live Shrimp from a Prawn, look at the long pointed beak which juts out from the front of the head. That of the Prawn is toothed, like a little saw. If the beak is quite smooth its wearer is a Shrimp.
Until Prawns are grown up, they haunt the sandy shallows with their cousins the Shrimps. But the larger Prawns live in deeper water. They are generally caught in traps, as are their relatives, the crab and lobster.
Now look closely at a Prawn, and try to find how it swims. Turn it upside down. It has ten legs; and, under each of the horny rings of its body, you can see a pair of little paddles. They are fringed with hairs. When the Prawn or Shrimp is not in a hurry, he swims slowly but surely with the little paddles, or "swimmerets." If any danger threatens, he uses his tail, in this way:--It is made of five fringed plates, which, as you can see, spread out or close up, like a fan. As he doubles up his body, the plates spread themselves out. They strike the water with great force, and so send the Prawn or Shrimp quicklybackwards. As the body becomes straight again, the fan closes, ready for another stroke. To move quickly, the Shrimp or Prawn merely bends his body, then straightens it. The tail thus becomes a strong oar, driving him backwards with rapid jerks.
Look now at the Prawn's long, hair-like feelers. There are two pairs. On one pair are the ears, a special kind of ear for hearing in water.
You will notice that the Shrimp's eyes are on the end of short stalks. Each big eye is really a cluster of little eyes, rather like the "compound eyes" of insects. If you lift up the horny shield behind the head, you see a row of what look like curly feathers. These are the breathing gills.
Shrimps carry their eggs about with them; no doubt you have often found masses of eggs under the Shrimp's body. Each egg is fastened by a kind of "glue," or else the rapid jerking of the mother Shrimp would soon loosen the eggs and set them free.
The hard, shelly covering of the Shrimp and Prawn is like the armour of the crab--it will not stretch in the least. The body is easily bent, owing to the soft hinges between the hard rings. But the coat itself will not stretch. Then how do these little creatures grow? We see small Shrimps and large ones, so grow they must, in some way.
They are of the same family--thecrustacea--as the crab; and they grow in much the same way. The hard covering gets too tight for the body inside it. Then it splits across the back. After much wriggling, the Shrimp appears in a new soft skin. While the skin is still soft the Shrimp grows very quickly. Crustaceans have a funny way of growing, have they not? Instead of growing evenly, little by little, they grow by "fits and starts," a great deal in a few hours and then not at all.
Besides being good food for us, and for the fish, Shrimps and Prawns have another use. They are scavengers. They pick to pieces and eat the vegetable and animal stuff which floats in the sea. Before it can decay and become poisonous, these useful creatures use it up as food. Great numbers of Shrimps and Prawns are caught for our markets. Some are caught by men who push a small net over the sands near shore, but most are caught by theshrimp-trawl, a large net cast from a small sailing vessel.
The rocks, and the wooden piles of the pier, are often covered with the hard shells known as Barnacles, or Acorn Shells. If you slip on them with bare feet their sharp edges cut you. Each Acorn Shell is a little house. Have you ever caught a glimpse of the animal living inside?
If you will look very carefully, you will see that the Acorn Shell is made of three-sided pieces, closely joined. There is a little door at the top, kept tightly closed until the tide comes up and covers the rocks. Then watch, and you will see a bunch of tiny feathers appear through a slit in the door. This means that the animal is hungry, and has put its twelve legs out of doors to catch a dinner!
This is strange, but true! The Barnacle is always upside down in its home, and its twelve feathery legs are thrust out of the door at the top. They make a fine net, in which minute animals are caught and brought into the mouth below. This funny creature actually kicks its food into its mouth! If you own a magnifying glass, you can see this for yourself at the seaside.
You will not be able to see the mouth, however, which is inside the shell. It is fitted with moving parts, and feelers, like the mouth of a crab. Also, the Barnacle has a good set of teeth to grind its food. It has no real eyes, having no use for them. Of what use are eyes to an animal standing on its head in a small dark shell! Now and then it casts its coat (like the Crab and Shrimp). The old coat is rolled up and thrown away outside the door.
Now comes the strangest thing of all. As a baby, the Barnacle is a free swimming creature. It has three pairs of legs, a tail, a useful mouth, and one eye. After kicking about in the sea for some time, and changing its skin, it changes its shape entirely. It now looks more like a tiny mussel. It has two little "shells," two eyes, legs, and feelers. Now its swimming days are nearly over, and it must settle down. It gives up eating, and roves about looking and feeling for a place to settle on.
Finding a suitable spot, the little animal stands on its head. Then a kind of glue is formed, which fixes it for life to that place, head down. The two shells and the two eyes are now thrown off. The Barnacle quickly builds up a shelly house, and, after a life of adventure and change, becomes a fixed Barnacle for the rest of its days.
For many years people knew little of this strange animal. All its wonderful changes, and the way its body is made, tell us plainly that the Barnacle is actually first cousin to the Crab, Lobster, Shrimp and Prawn! It belongs to the class known as theCrustacea; but, for some reason or other, it has chosen to live its grown-up life fixed to a rock.
EXERCISES
1. How does the Shrimp swim?
2. Of what use are Shrimps and Prawns in the sea?
3. How can you tell a live Shrimp from a live Prawn?
4. How does the Barnacle obtain its food?
5. Give the names of five crustaceans.
PLANTS OF THE SHORE.
To pick a bunch of gay flowers you would look in the fields and hedge-rows, and not by the sea. Flowers, as you know, love moist soil, and not dry sand; and, like us, they prefer one food to another. Sand they do not like, and salt is a poison to them. Both of these are enemies to plant life.
Also, flowers choose sheltered spots. They do not like rough winds, and the glare of the sun shrivels them up. Yet there are plants with pretty flowers to be found by the sea, and many others with small, dull flowers. These seaside plants have to fight for their lives. The dry, shifting sand, and the salt spray, are enough to kill them, you would think. They have no shelter from the strong sea wind, nor from the fierce glare of the summer sun. The puzzle is, how do they live among so many enemies? For you know that the flowers of the field would at once die if you planted them in salt and sand. They would starve to death.
Even the strongest seaside plants shun that part of the beach washed by the waves. They leave that to the seaweeds.
Let us look first at some plants which have their home on the sand-hills. Here is a fine one, like a thistle, with stiff prickly leaves, and a stiff blue stem. In August it has blue-grey flowers. This plant is called Sea Holly, its leaves being like those of the holly. It has an unpleasant smell, yet its roots are used for making some kinds of sweets.
Now try to pull up a plant of Sea Holly. You find it no easy task. Then dig away the sand, and you see that its large roots have gone deep and far. All these plants of sandy places grow like that. Sand has no food or drink to give to plants. So they send their roots out, like plants in a desert, until they find what they want. Besides food and drink, they need a firm anchor in the loose sand. The Sea Holly, with its roots deep down and far-spreading, can hold its own, though the gale tears at it and throws its sandy bed here and there.
We pass many small creeping plants as we walk in the dry sand. There is a pretty Sea Convolvulus, with its stems deeply buried. It is a cousin of the common Bindweed. Then we see many plants of Thyme, and a few ragged bushes of Gorse. We notice that several little plants grow near the Gorse, as if they had crept there for shelter. The sea breeze has blown the sand into heaps, and even on these dry, thirsty hillocks we see many tufts of grass.
These Couch Grasses and Dune Grasses, as they are often called, are coarse and hard. Cattle pass them by in disgust. Yet they are the most useful plants on the shore. They can live and spread where other plants die. They have very long underground stems, which go through and through the dry, loose sand. The wind does its best to bury them in sand, but they send up hard, sharp buds, and go on living, and spreading.
Bit by bit, the sand is held together by the matted stems of these grasses. It becomes firm, instead of loose; the wind can no longer blow it about. Then other plants can grow in that place. You know how men go out to the wild parts of the earth and, by hard work, make those places ready for others to settle there. Well, the sand-grass works like that. It prepares the way for useful plants to grow in places where they could not grow before.
Quite near to the sea we shall find a very strange little plant. It has no leaves, only fleshy, jointed stems. It is known as the Glass-wort, being full of a substance useful in making glass. It belongs to a family which seems to delight in deserts and salty soil! They have all sorts of dodges to help them live in such places. For instance, their leaves are fleshy. Squeeze them, and they are like wet, juicy fruit.
The Sea Beet is also a member of this family. The Red Beet, as well as the Mangel-wurzel, we owe to this humble seaside plant. Most of our sugar comes from the Sugar-beet.
Another useful plant is the Sea Cabbage, which grows on some parts of our sea coast. It is rather a ragged, tough kind of Cabbage, and perhaps you would not choose it for your dinner-table. We have more tempting sorts in our gardens--Brussels Sprouts, Broccoli, Cauliflower, but long, long ago the wild seaside cabbage was the only one growing. Men found it to be eatable, and began to plant it near their huts or caves. From that small beginning all our garden cabbages have come.
Walking a little farther from the sea, we leave the sand and come to stones, rocks and cliffs. We pass a pretty plant, the Sea Lavender, and another, the Sea Stock. They love best the sandy, muddy parts of the shore. Their lilac flowers look bright and pretty. Coming to the rocky places, we find tufts of the flower known as Sea Pink or Thrift. Its leaves are like grass, and its flowers form a round pink bundle at the top of a bare stalk.
There are many tufts of Thrift growing among the rocks; and each tuft has a number of pink flowers. In some places you could step from one tuft to another for several miles. Bare and ugly stretches of coast are made into a gay garden by this lovely flower.
Here and there on the rocks is a plant with large yellow blossoms--the Yellow Horned Poppy. It is a handsome plant, and you are surprised to see such fine flowers among dry shingle, sand, or rock; but the Horned Poppy is well able to stand the salt spray and storms of its favourite home. When the petals have dropped, a green seed-pod is left. It is very long--nearly twice as long as this page and looks much more like a stem than a seed-pod.
Sometimes this seaside poppy is seen growing high up the face of the cliff, where only the jackdaw and sea-birds can find a footing; and many another plant may be seen there too. The cliffs are full of cracks, some tiny and some wide. In these places there is always a certain amount of dirt and grit. You could hardly call it "soil," and most plants would starve if you planted them in such a place.
These plants of the rock and cliff are not so proud. They have very long and very thin roots, admirably suited to pierce the grit, and explore the cracks in the rock, to find the moisture they need. Besides this, they have fleshy leaves which help them to keep alive. The Stone-crop and the Penny-wort are well-known plants of this kind. They grow where you would least expect to find a living plant. Neither heat nor thirst seems to kill them. Mother Nature has found many a wonderful way of helping her children to live.
EXERCISES
1. Why do plants which grow in sand have such long roots?
2. In what way are the grasses growing on the sand so useful?
3. Give the names of four flowering plants of the shore.
4. Where would you look for the Stone-crop and Penny-wort?
5. Why do these two plants have such thin roots?
FLOWER-LIKE ANIMALS.
The prettiest of the creatures of the shore is the Sea Anemone. No one can see it without being reminded of a flower, an Aster or Daisy, with a thick stalk and many coloured petals; but, knowing how it is made, and how it lives, we place it in the Animal Kingdom, though among the lowliest members of that Kingdom. It is a cousin of that strange creature, the Jelly-fish, which we shall look at in another lesson.
When the tide falls, you can walk among the rocks and pools by the sea, and find Anemones in plenty. They are fixed to the rocks. Some are under the ledges, out of sight, others are low down, half buried in the wet sand; and others are on the sides of the rocks, looking like blobs of green, brown, or red jelly. Feel one of them. It is slimy, and rather firm, not so soft and yielding as the Jelly-fish. You cannot easily pull it from the rocks without harming it; but you will find other Anemones on stones and shells; and these you can put in a jar of sea-water, with some weed, and carry home to examine later on.
When covered with sea-water the ugly blobs of jelly open out like beautiful flowers. In some places along our coast the floor of the sea is like a flower garden, gay with thousands of coloured Anemones.
Those little "petals" are reallytentacles, used for catching and holding food. We will use a shorter word and call them feelers. They are set in circles round the top of the Anemone, and there are many of them. The Daisy Anemone, for instance, has over seven hundred feelers. Each feeler can be moved from side to side, and can also be tucked away, out of sight and out of danger; but, when hungry, the animal spreads them widely, for, as we shall see, they are the net in which it catches its dinner.
The whole body of the Anemone is like two bags, one hanging inside the other. The space between the two bags is filled with water. The feelers are hollow tubes which open out of this space; so they, too, are filled with water.
The Anemone can press the water into them, and so force them to open out. In rather the same way you can expand the fingers of a glove by forcing your breath into them. The Anemone, you see, can open or close just as it pleases.
What does it eat, and how does it find food? Perhaps you have watched an open Anemone in a pool, or in a glass tank, and seen it at its meals. A small creature swims near, and touches one of the feelers. Instead of darting away, it appears to be held still; and then other feelers bend towards it and hold the victim. Then they are all drawn to the centre of the Anemone, carrying their prey with them; and the feelers, prey and all, are tucked out of sight.
That is the way the Anemone obtains its food. As soon as the feelers get hold of a small animal they carry it to the opening of a tube in the centre. This is the mouth, leading to the stomach. Very often the feelers, with their victim, are tucked away into the stomach, and the feelers do not appear again for some time. Is not this a strange way of eating!
Much stranger still is the way in which the food is held, and made so helpless that it cannot escape. On the skin of the Anemone there are many thousands of very tiny pockets, or cells. Each cell contains a fine thread with a poisoned barb at the tip, The thread is packed away in the cell, coiled up like the spring of a watch. As soon as anything presses against the cells they shoot out their threads. Thus the tips of many poisoned threads enter the skin of any soft animal which is unlucky enough to touch an Anemone.
If your own skin is tender, these little stinging hairs will irritate it, but not enough to hurt you. It is different, however, with the small creatures of the sea. They are made quite helpless when caught by hundreds of these strange threads. We shall find similar poison-threads in the Jelly-fish; and these, in some cases, can cause us serious illness. You cannot see them without the aid of a microscope.
All those parts of its food which the Anemone cannot digest, it throws out again. If you feed an Anemone on raw meat, it tucks the pieces into its mouth, and, some days after, throws out the hard part of the meat, having taken all the "goodness" from it.
No doubt the Anemones themselves are eaten by other animals in the sea, but many kinds of fish will not touch them. You may remember that we noticed an Anemone which lived on the stolen home of the Hermit Crab. The crab lives in the whelk shell, and the Anemone lives on the roof, as it were. In nearly every ocean, all over the world, these two partners are found, using the same shell. It is thought that the Anemone lives there for two good reasons. First, the Hermit moves from place to place; you can see that this would give the Anemone a better chance of obtaining food. Also, bits of food float to the Anemone when the crab is picking his dinner to pieces.
The crab seems to like having his strange partner with him. No doubt the Anemone is of some use to him, or he would at once pull it off. It is thought that the Anemone protects him from his enemies, the fish. Some of them would swallow the whelk shell, crab and all, but they would not eat one on which an Anemone was fixed. We are notsurethat these reasons are the right ones. All we know for certain is, that a crab and an Anemone have, for some good reasons, gone into partnership.
Anemones have large families. Sometimes they have numbers of eggs; at other times their little ones come straight into the world as very tiny Anemones. A boy who kept a large Anemone in a tank of sea water, was astonished to find that in a short time, he had not one, but hundreds, of the creatures. The tiny Anemones were fixed to the glass and rock, all fishing for food with their little outspread tentacles. Sometimes the Anemone will calmly divide itself into two, each half becoming a perfect Anemone!
Anemones are of many shapes, sizes, and colours. The loveliest of our British ones is the Plumose Anemone. It is like a carnation, and may grow to be six inches high--that is, nearly as long as this page. It is known by its shape, not by its colour. It may be any of these colours--brown, deep green, pale orange, flesh colour, cream, bright red, brick colour, lemon, or pure white.
There are many other creatures in the sea which resemble plants and are often mistaken for them. The Sea Lily (p.49) is one of the flower-like animals; it is a relative of the Starfish, living in deep water. The Sea Mat (p.59) is often found on the shore. It seems like a horny kind of weed, but is really a colony of tiny animals, each one having its own little cell to live in.
EXERCISES
1. How does the Anemone expand its "feelers"?
2. In what way does the Anemone catch the small animals on which it feeds?
3. Where is the mouth of the Anemone?
4. In what way might the Anemone be of use to its partner, the hermit crab?
SEA-WEEDS AND SEA-GRASS
We think of weeds as useless plants which insist on growing just where they are not wanted. So it is a pity thatSea-weedsare so named, for the part they play in the sea is a useful one; and they are often beautiful, though they do not bear flowers like so many plants of the land. You see draggled heaps of them, lying on the shore where the waves have thrown them. They are best seen in their proper home, buoyed up by the water, and spreading out their broad coloured fronds, or long waving threads. There are, in many places, meadows of Sea-grass, and forests of Sea-weed! Mother Earth still has her carpet of green, even when covered by the salt water. The plants are very unlike those of the land, but, as you will see, they are of great use. We will suppose you put on a diving dress. Then you can walk out, under the water, and explore the forests of the sea.
Down by the line of low tide, before you have waded up to your knees, you find plants clinging to the rocks. They cover them with a slippery coat of green; when you turn these Sea-weeds over you find periwinkles and other animals feeding or hiding. Sea-weed makes good "cover" for the creatures of the rock-pools, who have many enemies to fear.
You notice that most of these shore weeds are green, sometimes as green as young grass. Pull up a bunch of the weed, and you find that it clings to the rocks and stones, but has no real roots. Seaweeds belong to a humble family in the world of plants, having no real roots, no flowers, and no real seeds. They can attach themselves to the stones or rocks. Along comes a great wave, and perhaps they are torn up; but this does not harm them, for they still live as they wash to and fro in the water, until they cling to another rock. Or they are thrown on the shore to die, or else to be washed back to sea by the next tide.
The Sea Lettuce or Green Laver is a common seaweed near the shore. Its broad, crinkled and bright green leaves are rather like those of a lettuce. Sometimes it is boiled to a jelly and used for food. Many other sea-weeds are good to eat, and on some coasts there is a regular sea-weed harvest.
Now wade into rather deeper water, and you find a great mass of the Bladder Wrack. Most schoolboys know it, for the little bladders of air in the leaves explode with a pop if you squeeze them. The Bladder Wrack, and others of the same kind, are torn up by the fierce waves in a storm, and tossed on the beach in heaps. They are gathered by the farmer who knows how to value a cheap manure for his fields. Some kinds are also of use in packing lobsters so that they come to market nice and fresh.
When you have walked--in your diving dress--to deep water, you find yourself among a tangle of olive-green weeds. They are below the line of low tide. All round you is a forest of dark-green ribbons with wavy edges. The ribbons are tough and very long, and cling tightly to the rocks. These ribbon-weeds, and others of the same kind, are known as Tangles. Round some parts of our coast they make wide, thick beds in the sea. Though the ribbons may be six feet long, they are not so wide as the palm of your hand.
Another sea plant, which grows in tufts in rather deep water, is called Irish Moss; it is green, brown or purple in colour. I do not know why it should be called Irish Moss, for it is not a moss, and it grows all round the English, as well as the Irish, sea-coast. But sea-weeds have strange names; indeed, many of them have no everyday names at all. Irish Moss is used for food, after being boiled to a jelly. It can also be made into a gum or glue, and has often been so used.
Now, if you were to walk still farther on the bed of the sea, into deeper water, you would find the prettiest of all the sea plants. These are the pink and red sea-weeds. You also find them on the beach, but only after they have been torn from their home in the deep water. They grow on the rocks, in pretty coloured tufts.
If you dive still farther, into the dark depths of the sea, you find beds of ooze and slime, and rocks and weird fishes, but no plants. Why is this? Like the land-plants, these sea-plants must havelight. They cannot grow in the blackness of very deep water. Can you guess why some sea-weeds are green and others red? Those growing in the shallow water of the shore are green, like land-plants, because the sunlight reaches them. Only part of the light can pass through deep water; and so, in these shady places, the sea-weed is reddish in colour.
We see, then, that (1) green sea-weed grows by the shore; (2) brownish-green sea-weed likes deeper water; (3) red sea-weed grows in deep water; and (4) in very deep water there is no weed at all.
We must not forget the grass of the sea. It grows in narrow blades, often a yard in length, and as wide as your thumb. It is not a sea-weed, but a real flowering plant, which, for some reason or other, loves to grow under water. It creeps in the sand and mud, with green leaves growing up as thick as corn in a cornfield.
All these waving green leaves make large meadows in the sea; and sea-snails, fishes, and crabs hide in it, just as all manner of living things hide in the grass of our meadows. The proper name of this strange plant is Sea Wrack. When dried, it is useful for packing up china, and covering flasks of oil.
Now we come to the real use of sea plants. They are food for all the hosts of small animals of the sea. These eat it as it grows; or else, like the mussel and oyster, swallow the tiny scraps of it which float everywhere like so much dust.
The shell-fish, and other animals which feed on sea plants, are themselves eaten by other sea creatures, and these in their turn are eaten by crabs, lobsters and fish, which are eaten by us. It reminds you of a chain. The first link in the chain is the sea plant, the last links are the fish and ourselves. So, you see, the weeds and grass of the ocean are of very great value indeed.
EXERCISES
1. Give the names of three common Sea-weeds.
2. What is the colour of the weed found in deep water?
3. Why cannot Sea-weed grow in very deep water?
4. In what way are sea plants most useful?
THE JELLY-FISH.
Or all the queer children of Nature which live in the sea, the Jelly-fish is one of the queerest. You often find it on the shore, especially after a severe storm. There it lies, a mass of helpless jelly, which slips and breaks through your fingers if you try to lift it.
It cannot move back to its watery home, and in a short time the sun's warmth will have dried it up, leaving but a mark on the sand, and a few scraps of animal matter; for these strange creatures are little else but water. A Jelly-fish, which weighed two pounds when alive, would leave less than the tenth part of one ounce when dried!
There is a story of a farmer who, on seeing thousands and thousands of Jelly-fish along the shore, thought he would make use of them. He decided that they would serve as manure for his fields, and so save him much money. He went home, and sent men with wagons to be loaded with the Jelly-fish. This was done, and the Jelly-fish were spread over the soil. On looking at his fields the next morning, the farmer was astonished to find that every scrap of his new manure had vanished as if by magic!