Description: 

Hermit crabs are obsessed with snail shells. These crafty little crabs, 

found in California's rocky intertidal zone, are more than happy to let the

snails build them a perfect home. When the crabs find a snail shell they like,

they hop right into their new abode. 

Transcription: 

Hermit crabs are obsessed with snail shells. And these crafty little crabs are more

than happy to let the snails do all the work to make their future homes.

In these Northern California tide pools, turban snails invest years, sometimes 

decades, growing their shells. They pull calcium carbonate right out of the water 

to do it. They spend their days eating the algae that coats pretty much everything

in these rocky, shallow pools. The rugged shells protect the snails’ squishy bodies

from the relentless surf. They’re way stronger than your average garden snail shell.

Those sturdy curves catch the attention of these grainy and hermit crabs. 

But hermit crabs won’t kill the snails to get them. They wait for a snail to die and 

then rush in. This new home comes with a free meal. Escargot, anyone?

It’s a competitive market. And they’re constantly looking to upgrade.

Maybe they’ve outgrown their current place. A shell that’s too small hampers 

growth. And a damaged shell like this one just isn’t safe. While the front of their

body is covered in stiff armor, their elongated back half is soft. It curves to match

the shell’s spiral shape. At the very end of its body, deep inside the shell,

modified legs called uropods grab on, like the arms of an anchor. Before they make

any big moves, they usually inspect their new potential digs. If they like what they 

see, they make sure the coast is clear, hold on to both shells, and… Much better,

now to get this place cleaned up. But the crabs never get too attached. 

They might occupy this shell for just a few hours, if they find something better.

Sometimes hermit crabs will squabble over a particularly desirable abode. 

Or bully the current occupant into abandoning its shell by banging against it.

But the tenant hiding inside won’t give up its most prized possession easily.

If there’s one thing they can count on, though, there will always be another shell.

And another, and another, and another. 

Questions: 

1. What is a hermit crab? What are they obessed in?

2. How do snails grow their shells?

3. How do hermit crabs look for their new home?