大象传媒

Blackpool pier is covered in barnacles and mussels. The competition for space down here is incredible - it's a real case of overcrowding. The barnacles are all over-growing each other, even living on the mussels. They are both well adapted to withstanding hours of exposure as the tide goes out - they close their shells and the barnacles even take a little water into the shell with them. The sand, however, looks completely devoid of life - except for people, of course. When the tide comes in, the beach begins to buzz with a completely different kind of activity. All you've got to do is wait for the water. After footprints and sandcastles are swamped, other builders and picnickers get busy. The top layer of sand is rich in food for the furrowshell, though it only dares expose a hoover-like syphon to suck it up. The left-overs are expelled nearby in a little sand fountain. As on land, the ocean has its own kind of vultures. Masked crabs only reveal themselves by day in the breeding season. They fight for dominance. A winner is established without casualties or loss of valuable limbs. Finding food hidden in the sand requires special techniques. The gurnard seeks out buried sand eels with its skill of 'taste by touch'. Its legs are modified fins and their tips acts as tongues. An equally effective method is ambush. For all their armour plating and claws, crabs have their enemies.