There were a number of whelks. Whelks, you know, are sea-snails. They live in shells, and draw themselves in and out of them very quickly. The moment Peggy put them into the tub, they pushed their shells on to their backs as snails do, and began crawling slowly along the edges of the tub.
“O Janet, my whelks will walk out and get lost!” Peggy cried. But Janet told her she thought they liked the water best, and would stay in it.
Then there were three mussels. Mussels live in tight, dark blue shells; but when they please they can open their shells, much as you open a portfolio, for there is a kind of hinge at the back of the shell. However, they too were sulky, and lay still quite tight shut.
Janet had picked up a very large shell, and put it into the tub, and Peggy asked her why. She said they would see before long. Now she took the large shell and laid it in the water. Peggy watched, and suddenly she saw a thin green leg come stealing out; then another and another, till at last a tiny green crab came scrambling altogether out of the shell, and ran rapidly about the tub.
“O Janet, it’s a little crab! How did you know? Do they always live in these big snail shells?” Peggy cried.
Janet told her that they were called hermit crabs, and that they lived in the cast-off shells of other creatures, just using them as houses.
“Put your hand into the water, Miss Peggy, and you will see him run in,” Janet said.
Peggy shook her hand in the water, and saw the little crab scuttle away and get into his shell like lightning.