There are three common species found on the Marine Reserve shores. The Common or Green
Shore Crab is a certain find on this shore hiding under weed, in crevices or in the
many rockpools. You may also come across what appear to be dead crabs but which are in
fact their old discarded shells. Having a hard skeleton on the outside of the body
means that crabs must cast off this shell when it wishes to grow. Like when we grow
out of an item of clothing. Having crawled out of the shell, the new skin is very
soft. The crab then inflates itself with water so that when the skin hardens to form a
shell over the next few days, there is room to grow into it. The old shell is left in
tack but eventually disintegrates.
If it is picked up the Green Shore Crab will wave its pincers about in attack.
However the Edible Crab is generally a reddish-pink colour with black tips to its
pincers and tucks them in when handled. They are easily identified from the shape
of their shell resembling a Cornish pasty.
The Hermit crab is a little different from Shore and Edible crabs, in that it lives
in shells left vacant by the original occupants. This Crab has a very soft body so
it requires another shell for protection. As the crab grows it will have to find a
larger shell. It will sometimes fight with another Hermit crab to get its shell.
All crabs are scavengers: That is, they feed on dead and rotting material. In this
way the help to keep the shore clean.
When you are exploring the seashore, you will notice the rocks are covered in small
white volcanoes. These are Barnacles, animals related to crabs, lobsters, prawns
and shrimps. Barnacles begin their life in the sea as minute floating larvae making
up part of the plankton. In an amazing underwater transformation the larvae settle
out on any available surface and develop into the adult form, which we find on the
shore. The adult Barnacles are glued head down to the rock. When covered, two little
doors open in the top of the volcano shaped shell and the Barnacle's feathery legs
kick out to capture food particles. Once attach to the rock a Barnacle cannot move away.