Choosing cockles
Break . . .
Opening a cockle shell is not without problems. It is not easy to crack, especially if the shell is thick.
. . . and pry apart
The cockle has a powerful muscle that holds the two "valves" of the shell together, and prying them apart can be difficult. Try it yourself the next time you come across a cockle!
Opening methods
Some individuals hammer at the edge of the shell until it breaks; others pry it open. The oystercatcher's bill is shaped like a chisel. This enables it to work its bill in between the valves of the shell until they split apart.
Choosy bird
Lying around the oystercatcher are cockles ranging in size from small to medium to large. But only those of medium size, 3-4 centimetres across, have been opened. Why?
