hermit crabs use abandoned seashells as
mobile homes as a crab grows its shell
becomes an ever tighter fit so
eventually a crab needs to move in to a
bigger one suitable empty shells are few
and far between and this one is far too
spacious for this crab but instead of
continuing its search this small crab
settles down to wait
[Music]
other crabs also looking to upgrade to a
bigger home soon gather whenever a shell
washes ashore unfortunately the new
shell is too big for them to despite
that the gathering crabs begin to
measure each other up and then they do
something really rather extraordinary
they arrange themselves into an orderly
queue the biggest of the front smallest
at the back they're lining up with one
aim to exchange properties but none of
the crabs can make a move because the
chain is not yet complete they're all
waiting for the right-sized crab to come
along and this is it
[Music]
the latest arrival pushes to the head of
the queue at first the chain falls apart
as it reforms a small crab finally makes
its move and takes its place at the end
of the line after a close inspection the
big crab moves in this triggers a chain
reaction each crab hurriedly moves into
the shell vacated by the crab ahead of
it in the line
just as the small crap attempts to move
into its new home the fresh arrival
muscles in
[Music]
to be left without a shell is a death
sentence
a naked crab will quickly cook under the
intense tropical Sun
[Music]
but after all the swapping there is
still one shell left sadly it's no
bigger than this small crabs original
shell and worse it's got a hole in it
[Music]
but even a bad shell is better than
being homeless
[Music]