Natural Protection PDF

Natural Protection Most crabs have hard shells. Their shells protect them like suits of armor. When a crab's shell gets too tight, it pulls itself out. Under the old shell, a new one has already grown. A hermit crab has hard front claws, but it has a soft shell in back. For protection, a hermit cr...

Natural Protection Most crabs have hard shells. Their shells protect them like suits of armor. When a crab's shell gets too tight, it pulls itself out. Under the old shell, a new one has already grown. A hermit crab has hard front claws, but it has a soft shell in back. For protection, a hermit crab moves into another creature's shell. For example, after a sea snail dies, the empty shell it leaves behind makes a perfect home for a hermit crab. The crab squeezes right into the shape of the snail's shell. The crab's head, legs, and pincers poke out of the opening. When it grows too large in this borrowed shell, it finds a larger one. Leaving the old shell behind, it moves into a new one. A hermit crab's shell may not always protect it. If an octopus comes along, for instance, it can stick one of its eight arms into the shell's opening. Then it can pluck the crab out. Some hermit crabs have extra protection. They have creatures called sea anemones sticking to the outsides of their shells. Anemones have many tentacles. Their tentacles have stinging cells. An octopus may not even approach a hermit crab's home when a stinging watchdog guards it.