L IMULUS, the king crab, slept all winter on the quiet bottom of Holiday Bay, without moving a single claw. The water in the bay was very cold but that did not bother King Limulus.
When the autumn weather grew chilly, he did not need to look at a thermometer or worry about warming his home with a furnace fire. He made no attempt to keep warm. He just lay on the sand while his body grew numb with cold. By the time winter really came, he could not move or even feel.
During the fall, barnacles settled on his shell and little seaweeds began to grow. Before Christmas the King looked like a weedy rock lying on the bottom of the bay.
King Limulus stopped among the seaweed.
In time the spring sun warmed the dry earth. On land pussy willows bloomed. Robins came north again and began to build their nests. But the deep parts of Holiday Bay stayed cold, and the sleepy King did not awake.
The stiffness did not begin to come out of his joints until some time after May day. First he stretched one leg, and then another, and so on until he had stretched all twelve of them. He lifted his long spinelike tail. Being able to move his body, he began to crawl toward shore. He came to a place where worms burrowed in the sand, and paused to dig them out and eat his first spring breakfast.
King Limulus had a strange way of eating. His mouth was on the under side of his head, between his six pairs of legs. First he pulled the worms out of the sand. Then he worked his legs to and fro, chewing the worms with sharp, hard spines. By the time he put the worms into his mouth, all he had to do was to swallow.
After the King had finished his meal, he crawled, half buried in the sand, toward the warm shallows near Holiday Shore. When he found a place where the sand was packed hard, he dug into it with his long sharp tail and used it to push himself along.
It took King Limulus several days to reach the shallows near the shore, where he stopped among the seaweeds and eel grass to warm himself and eat his dinner. Sun, shining through the water, heated his sandy lunch counter. In it were hundreds of pink and green burrowing worms. These made a feast fit for king crabs, and Limulus was not the only one of his kind who came to enjoy the treat. Indeed, in that sunny, watery lunch room, many members of his family met for the first time that spring. Among them may have been his father and some of his sons, but, if so, Limulus did not know one from another.
One day the King had rather a bad jolt. He was hunting worms in the shallows, as usual, while waves rolled up on Holiday Shore. One of them picked him up and threw him high on the beach.
It dropped him, top-side-down, and there he lay with his legs waving in the air! You need not feel sorry for him, however, because he was not nearly so helpless as he looked. He bent his shelled body and reached down with his tail. As soon as he could bend back far enough to stick the tip of his tail into the sand, he turned himself over with a twist and a flop. Then he crawled back to the bay as fast as his legs could go.
Only ten of his twelve legs really helped him travel. Those of the first pair were so short that they only wiggled about near his mouth. The last ones were extra long and ended in strong, paddle-shaped joints. The King used them to push sand aside when he burrowed into it for worms.
Behind his legs, the King had five pairs of broad plates. Under three of these were the gills with which he breathed air mixed with the water where he lived. The oxygen in the air, as you doubtless know, is as necessary to sea creatures as it is to land animals.
The gills with which fishes breathe are near their heads. So are the gills which baby frogs and toads use while they are tadpoles. But Limulus carried his gills just in front of his tail. Water animals, of different groups, have gills of different sorts and in different places. There are the infant dragon flies, for instance, which wear their gills in the tips of their tails.
While the King was turning himself right-side-up, the children playing near by came to watch him. They saw that his head was a big, horseshoe-shaped thing covered with a shiny, brownish-green shell. At each side, under a sharp point, was a glowing green eye. Two other eyes were placed near the front of his head. It is easy to overlook these for they seem to be merely two dark spots.
Fastened to the head by a wide joint was the broad part of the body that covered the gills. On the edge of each side were six short sharp spines, and at the tip was the long spine that formed his useful tail.
Were the King's eyes of any use to him as he hurried back to the bay soon after he had righted himself?
No. He bumped into the stones that lay between him and the water and almost turned over on his back again. Even after he reached the water he swam thump into a rock and became tangled in some drifting seaweed. In spite of his two pairs of eyes, the King acted as if he were blind.
Queen Limulus meanwhile came to the bay and also began to hunt for worms. She looked like the King, except that she was bigger and broader and the legs of her second pair were shorter than his.
The King and the Queen seemed to pay no especial attention to each other, yet they did not go far apart. One morning, as the tide came in, they swam together as far up as they could and then crawled up on the beach.
There Queen Limulus dug a hole, while the King sat behind her and waited. In the hole she laid half a pint of eggs. Since each egg was very, very small it took about ten thousand of them to make that half pint. A great many eggs to leave in one nest!
Do you rather wish that the King and Queen had stayed beside the nest to guard it? They soon crawled away and never came back. But that was perfectly all right. There was not a thing they could have done if they had stayed. Those eggs were left where the sun could give them all the heat they needed. The warm sand that soon covered them was a satisfactory incubator.
Suppose we watch a single egg among the ten thousand Queen Limulus laid. Soon changes began to take place inside the clear, tough shell of the egg. In a week, traces of legs might be seen. Soon a head and body began to grow. In three weeks the baby could roll around inside the shell, but it made no attempt to get out.
Baby Limulus just before hatching.
It was not until a month and a half after it was laid that the egg hatched. Then Baby Limulus went for a swim in Holiday Bay.
Baby Limulus just after hatching. He has not yet started to grow the long, sharp spine that will serve as his tail.
For about three weeks he swam here and there, dodging the mouths of hungry little hunters among the eel grass and rocks. Many of his brothers and sisters were caught and eaten by fish and sea anemones; but even so there seemed to be a good supply of infant king crabs in the bay.
Baby Limulus was rather a good hunter and caught and ate swimmers smaller than himself. As he grew, his tiny shell became too tight a fit for him; and one day he split it and appeared in a new and larger coat that had formed inside his first one. About that time he stopped his steady swimming and settled down in a sandy pool where the water stayed even when the tide was out.
This was his home for some time. He ate and grew and shed his shell each time he needed a bigger one. By the time winter came, he was fast asleep in the sand. There he lay until the warm spring sun wakened him and made him feel spry enough to hunt for worms.