Furman Kang, age 9, of Richmond, Virginia, for his question:
How big do starfish grow?
A certain starfish has been in the news lately. He is called the crown of thorns and he is a whopper. Often he grows to be more than a foot wide and experts say that he may be growing bigger than usual. If this is true, someday he may become the world's biggest starfish. But at present he is not. At least nine other starfish are twice as big as the crown of thorns and the giant of the family may be four times his size.
Actually we should not call them starfish. They are not related to the true fishes and many of them do not look like five pointed stars. Scientists and nature lovers would rather call them sea stars. Most of them do look like stars, even those that have dozens of pointed arms, and they all belong to the sea. Altogether there are about 2,000 different sea stars large and small. Some have five arms, others have 10, some have 20 and a few have as many as 50.
All sea stars start life as tiny eggs drifting in the sea. They soon hatch and swim around for six or seven weeks, searching for food and trying to dodge their hungry enemies. Then they sink to the bottom. They spend the rest of their lives hunting for food on the ocean floor. The more they eat, the faster they grow. But the smallest sea star never grows as big as a dime. From side to side he measures only half an inch. And most of the sea stars we find on our beaches are just about wide enough to fit in the palm of your hand.
As a rule, the giant sea stars live in cool, northern seas. Some of them are as big as cherry pies, and just as pretty. The spiny sun star looks like a golden pie crust with a fringe of 15 pointed arms tinted in tones of light orange and pink. The handsome sunflower star lives in the Pacific. People find him along the beaches and in the bays all the way from Alaska to California. Experts say that this fellow is most likely the biggest of all the sea stars. He may live 20 years and grow so big that he measures four feet from side to side. So far as we know, no other sea star grows this big. His bulky body may weigh up to 10 pounds, more than any other sea star.
The sunflower star has a small round button in the middle and his 24 arms look like long tapering petals. He may be orange or yellow, just like a sunflower. But he may be greyish colored, or violet blue or even rosy red. His tapering arms serve as fingers, arms and legs. On the underside they have about 15,000 tiny tube feet that act as suckers. He uses them to cling to rocks, to walk on the sandy bottom, to grab his food and to pry open shellfish. As a rule, the sunflower star grows only about two feet wide. But even at this size he is bigger and heavier than any other sea star.
Most sea stars, large or small, are as pretty as flowers but none of them act like flowers. They are very hungry animals. Fisherman dislike them because they devour oysters and other shellfish. The big sunflower star even raids the pots set out to catch crabs. Sometimes he gulps doom a prickly sea urchin as big as your fist. Next day, after the meat is digested, he spits out the spikes and the crusty shell.