A STER, the starfish, was hungry.
Aster was hungry so often that he did not wait long between meals. His favorite food was the mussels with dark purple shells and orange flesh. Thousands of them lived at the foot of Holiday Cliff. They could not hide or run away, for they had fastened themselves so firmly to the rocks that they could not pull themselves loose in time to escape.
As Aster was ready for dinner or luncheon, he walked to a colony of the purple mussels. How do you suppose he walked? Not by moving the five points or arms of his star, as you can move your hand by "walking" with your fingers. When Aster was ready to travel, he used hundreds of little, soft tubes on the under side of his queer body.
Each tube was about three-quarters of an inch long. It ended in a round sucker that could catch hold of rocks or shells. By stretching out some tube-feet and letting go with others, Aster managed to crawl over the stones. When he was going at top speed he walked six inches in a minute. But he did not walk steadily as fast as that, since he often stopped to feel things that were in the way. It was only when he was in a great hurry that he walked as far as twenty feet in an hour.
Of course he had to guide the movements of his many tube-feet. Otherwise he might crawl out into Holiday Bay instead of reaching the rocks where the mussels lived. He could not look to see where he was going although he had five eyes—one small red speck at the tip of each of his five arms. The best these eyes could do, however, was to tell light from darkness, so they were of no help to him in hunting for something to eat.
As Aster crawled, he stretched out a feeler from the tip of each arm, near an eye. These feelers looked much like tube-feet though they had no suckers at the ends. Aster groped here and there with his feeler-feet, somewhat as a blind man feels with his hands or his cane. These strange little organs had more than a sense of touch. They had a sense of taste, much like a sense of smell, as well. So by groping and smelling, Aster found his way to his food without needing eyes to help him.
When Aster came near them, the mussels shut their shells just as tightly as they could. But that did not bother the hungry starfish. He straddled a mussel, humped his body over it, and fastened the suckers of his tube-feet to its shell. Then he began to pull. For a while the mussel kept its shell shut; but Aster pulled and pulled and pulled until finally the purple shell opened.
At last the starfish was ready to eat. But he could not put the mussel into his mouth, or tear it to pieces as Hermit, the crab, tears clams. How was he to get his meal?
Aster had his own way of eating. Squeezing some muscles inside his body, he pushed his stomach out through his mouth! Soon the stomach covered the open purple shell and the bright orange body inside. Then it began to digest that orange-colored food and in this way Aster got his nourishment. When nothing was left of the mussel but the shell, Aster drew his stomach back into his body again, and went off to rest under some seaweeds.
This starfish is trying to turn over. He was eating purple‑shelled mussels even when the tide was out.
Aster did not really know much about what was happening near him. With eyes that sensed no more than a difference between light and dark places, he could not really see his neighbors. And though he had all the nerves he needed, he had no brain and could do no thinking. He did not even get very well acquainted with Mrs. Aster, who also came to Holiday Bay and laid many thousands of eggs in its shallow water.
Mother Aster's eggs floated in the water. They hatched into tiny, colorless things shaped somewhat like bunches of little thumbs. They could swim by means of movable hairs, but most of the time they merely drifted about. When currents or waves brought them close to the shore, some of them were pulled into the mouths of barnacles or mussels. This happened so quickly that they knew nothing about it.
After a time the infant starfish that had escaped being eaten stopped drifting and caught hold of seaweeds or eel grass. There they ate, grew, and changed into blunt, five-pointed stars. Soon they were shaped enough like Mother Aster to resemble her, though they were still very, very small. When they dropped among pebbles and rocks, they began to creep on tiny tube-feet and hunt for food.
The young starfish did not need to be very particular about their diet. They ate baby barnacles and baby clams part of the time. For some of their meals they ate bits of decayed things they found on the bottom of the bay. In this way they helped keep the places near them clean and such food did them no harm whatever.
You may think that all Mother Aster's children would be pink, as she was. Some of them were, but others were orange or brown, and a few were red or blue or purple. Young brother and sister starfish of this kind may have complexions of very unlike colors.
Every little while one or another of Aster's brothers or sisters had an accident of some sort. Quite often a hungry fish would come near enough to nip off an arm. The loss of a mere arm or two, however, is not so serious a matter to a starfish as you might think it would be. Aster himself was once caught by a big crab and seemed in danger of being torn in two.
How do you suppose Aster escaped? He simply let go of the arm that the crab held. Then he crawled off to hide among rocks. Soon the wound healed and a new arm began to grow. In time this became as large and as strong as the arm that was eaten by the crab.
One of Aster's arms was eaten by a crab but a new one soon began to grow.
When the tide goes out, Aster and others of his kind lie under bunches of cool damp seaweed. Since they do not crawl very far, a number of them often crowd together beneath the same shelter. Lift a bunch of seaweed and you may find seven or eight starfish, all squeezed into one corner. Look to see if some of them have small arms growing to replace arms they have lost.
When you lift the seaweeds you may find several big purple starfish.
If you live on the Pacific coast, you will not meet starfish just like Aster on the rocks. Instead, when you lift the seaweeds, you will find several much bigger purple starfish. Turn one of these over and you may see that he can eat even while the tide is out, for he will probably be holding a mussel or two within reach of his stomach.
You also can see how he uses his tube-feet to turn himself right-side-up if you lay him on his back. First he twists his five arms. Then he reaches out with his feet and begins to pull. In much less time than you expect, he turns himself over and lies on the rock, ready to eat another meal.
Aster has many relatives in the sea and some of them come to Holiday Shore. Two of these relatives are called sun-stars. They have big, round bodies and more arms, or rays, than Aster has.
One sun-star is dark red. Its skin is rather smooth and it has from nine to eleven slender, pointed arms. You sometimes will find it in deep tide pools or will see it lying under water on the rocks below Holiday Point.
Beside the dark red sun-star in the tide pool you may find a very spiny sun-star with as many as fifteen arms. Its body is covered with bunches of little spines, with longer spines on the sides of the arms. Its color is buff or pink, with spots and lines of red or purple. This spiny starfish in Holiday Bay is generally small but on the Pacific coast there is another spiny sun-star with fifteen to twenty arms that often grows to be two feet across. Sometimes a giant starfish of this sort is even twice as large as that—the very biggest starfish in the world.
Still another of Aster's relatives lives on the rocks near Holiday Point. He likes to stay where the water is so deep that low tide will not leave him dry, though he may also be found in some of the tide pools at the foot of Holiday Cliff.
This relative is Spiny, the green sea urchin. As he lies on the bottom of a tide pool, Spiny looks like a flattened ball of spines. Watch him closely and you will see that the spines move. You know, then, that they are fastened to something beneath, with muscles that move them to and fro.
Spiny has a hard, nearly round shell in which there are many holes. Through some of these holes he breathes. Inside a big hole, at the center of his under side, is his mouth with its five strong teeth. On his top and sides are many small holes through which Spiny pokes long tube-feet.
You will see all these holes if you find an empty shell lying on the sand of Holiday Shore. You will also see many shiny knobs, to which the sharp green spines are fastened.
By means of these spines the sea urchin walks. With strong muscles he moves them about, like a boy walking on stilts. Spiny, however, has many stilts, not two only, and he is in no danger of falling. If the stilts do not work fast enough, he reaches out with a dozen or more tube-feet and pulls himself over the rocks.
Just now, Spiny is eating a meal. He has found a patch of mosslike animals that are relatives of the sea anemone. He cuts them with his five white teeth. Pieces that might float away are caught by many little pincers among his spines. With his tube-feet Spiny takes these bits from the pincers and puts them into his mouth.
Some of the other sea urchins are eating the green plants that cover many of the rocks. Crawling as they eat, they leave bare trails across the surfaces where they live.
If a sea urchin gets plenty to eat without moving, he may sit for weeks or even months in one spot. His spines and teeth scrape the rock away while he eats, until he settles into a deep cup-shaped hollow. While he is digging, day after day, the sea urchin grows, so he makes his hole bigger at the bottom. Sometimes you may find old sea urchins that cannot get out through the small openings at the top of the caves they have made while feeding.
A group of green sea urchins
Spiny is a little sea urchin not more than two or three inches wide when full grown. His spines are short. There are sea urchins belonging to this same species, or kind, living in many parts of the sea. Children on the shores of Germany watch urchins like Spiny in the tide pools. Eskimo boys and girls see them in Greenland. If you should travel along the Pacific coast, you would find Spinies of the same kind all the way from Washington to Alaska.
You would find urchins of two other kinds along the northern Pacific coast also, one that looks like a little purple brother and another three or four times as large as Spiny with long red or purple spines. But not even this large sea urchin has spines as long as those of a kind living on the coast of Ireland. An urchin that an Irish child might find has spines longer than its body is wide.
Here is something interesting you will wish to know about Aster and Spiny: They belong to the only important group of animals that has never ventured into fresh water or lived on land.
You can find some worms, snails, crabs, and so on, dwelling in creeks, ponds, and on land, while some of their relatives remain in the ocean. But neither land nor fresh water tempts a starfish or a sea urchin of any kind. They all still remain in the sea where they have lived for millions of years.
English children often dig in the sand for cake urchins. These creatures have hundreds of velvety spines, and crawl along just under the sand. Instead of biting off plants, they shovel sand into their mouths, eating tiny creatures that live in it. You have seen that some sea cucumbers get their food like this—and they are distant cousins of the cake urchin.
Heart urchins live in sand, too. They dig holes about nine inches deep, using their short, flattened spines. They plaster a chimney leading up to the water, using a sort of glue that they make. Their food must come in through that chimney, while the heart urchin lies in wait. A lazy way of living? Of course, but the heart urchin seems satisfied!