Back Aa

On The Seashore

<h2>LESSON IV.</h2> CRABS. Little Crabs are to be found everywhere along the sea-shore--not the monsters of the fishmonger's shop, but small greenish-brownish Crabs. They live in the weed of the rock-pools, and in the wet sand. These are the Shore Crabs; the large Edible Crabs are a different kind, and live mostly in deep water. Shore Crabs are quarrelsome little creatures; the larger ones are always ready to gobble up the smaller ones, or to snatch their food and run away with it. If you put some dead mussels or fish in a pool, you will be amused at their antics. How they scramble and fight! Crabs do not believe in "table manners." <center><ANTIMG src="Illus027.png" width-obs="60%" title="THE CRAB." alt=""></center> <h4>THE CRAB.</h4> It is their taste for waste scraps of food that makes crabs of use in the sea. They are most useful scavengers. They clear the sea and beach of dead matter which would poison the air and water. For many years nobody knew how Crabs grew up. It was thought that a baby Crab was like its mother, just as a baby spider is a tiny picture of its parent. But no, the young Crab is as much like a Crab as a caterpillar is like a butterfly. Let us begin at the beginning--the egg. Mother Crab carries her eggs with her, under her tail, which itself is always kept tucked up under her body. Out of each egg there comes the queerest little creature! It is just large enough to be seen as it wriggles in the water. Then its skin splits, and there appears a quaint thing with long feathery legs, a big head, a spike on the back of its head, and another spike like a nose. Who would suspect this strange atom would turn into a Crab! Well, nobody did. It was called a zoea; but you can call it a Crab caterpillar or larva. The maggot is the larva of the fly, and the zoea is the larva of the Crab. With crowds of its brothers and sisters, the zoea kicks about on the surface of the sea. Fishes, and even great whales, swallow these tiny things by the million. The Crab larva eats and grows. Again and again its skin splits, and a rather different zoea appears. This happens about once a week, until, hey presto! the spiked zoea is now rather like a Crab. The spikes are gone, and now it has tiny claws, and two eyes at the end of stalks. Yet it still owns a tail. At last this is tucked up under its body, and lo! our little friend has changed into a very small Crab. No longer able to swim about, it comes to get a living in the shallow pools of the shore. Luckily, this helpless baby knows how to hide. He is helped by his colour, for it matches the green and brown of the weeds and rocks. He knows how to dig himself into the sand, and work his shell well down. Then only his funny eyes on stalks peer up at you. At this time of his life he has to "make himself scarce," and snatch his food when and where he can. <center><ANTIMG src="Illus028.png" width-obs="60%" title="PURSE CRAB." alt=""></center> <h4>PURSE CRAB.</h4> 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; these crustaceans, as they are called, are all cased up in a hard crust, which will not stretch the slightest little bit. But the Crab's body must grow! 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 as larvae or zoeas, 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. <center><ANTIMG src="Illus031.png" width-obs="60%" title= "HERMIT CRAB IN WHELK'S SHELL." alt=""></center> <h4>HERMIT CRAB IN WHELK'S SHELL.</h4> 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. <center><ANTIMG src="Illus0081.jpg" width-obs="50%" title= "HERMIT CRABS FIGHTING." alt=""></center> <h4>HERMIT CRABS FIGHTING.</h4> 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. <center><ANTIMG src="Illus034a.png" width-obs="50%" title= "HERMIT CRAB WITH SEA FLOWERS." alt=""></center> <h4>HERMIT CRAB WITH SEA FLOWERS.</h4> 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. <center><ANTIMG src="Illus034b.png" width-obs="50%" title= "HERMIT CRAB WITH SEA FLOWERS." alt=""></center> <h4>HERMIT CRAB WITH SEA FLOWERS.</h4> 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!". <center><ANTIMG src="Illus035.png" width-obs="60%" title="THE LOBSTER." alt=""></center> <h4>THE LOBSTER.</h4> 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? <hr> <div style="break-after:column;"></div>

1 of 2

2 of 2

Update Required To play the media you will need to either update your browser to a recent version or update your Flash plugin.