A Lobster Grows
Down
on the ocean floor, a lobster hides in a rocky cave. It
picks and scratches at itself. Why does its dark blue-green
shell seem so itchy? It’s time for the lobster to
grow.
As a lobster grows bigger, it needs a new shell, just as you need new clothes and shoes as you grow bigger. How does it get one?
First it has to molt, which means to shed its old shell.
Bend over and touch your toes. Do you feel your back stretch? That’s just how a lobster starts to molt. But when it bends at the middle and stretches its back, its shell splits open.
Next it must pull itself free. It works hard to wiggle its big claws out through the tiny armholes of its shell. It struggles to pull out its eight skinny legs and long antennae. The many small paddles that stick out under its body have to come out, too. In all, the lobster has to tug twenty-eight body parts out of its narrow shell. Imagine pulling a tight turtleneck over your head twenty-eight times!
At last it has the front half of its body free. Then the lobster switches its tail back and forth to knock off the rest of the old shell.
Now its body shines a bright blue-green. It is as smooth as silk and as soft as a sponge. With no hard shell to protect it, the lobster must stay hidden in its rocky cave. There, as it rests after the hard job of molting, its body begins to grow bigger. In two or three hours, a new shell starts to form.
Like your bones, the lobster’s shell contains a lot of calcium. It eats the old shell to get more calcium for the new one. You drink milk and eat vegetables to get calcium to build strong bones.
At first, the lobster’s new shell is rubbery. But in a few weeks it turns hard. Now the lobster can’t grow any larger until it molts again. Very young lobsters molt several times a year. An older lobster molts only once a year.
Unlike you, the lobster will never stop growing. Even as an adult lobster, it will outgrow its shell. Each time it gets a new shell, it will get a little bigger. If it lives about fifty years, it will grow into a giant lobster. Giant lobsters have bodies as long as baseball bats and claws the size of catchers’ mitts.
So if you see a lobster hiding in a rocky cave, don’t disturb it. It may be growing.
