. 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.

[Illustration: PURSE CRAB.]

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withdrawn even from the legs, claws, feelers, bristles, eye-stalks and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