An oyster: they can hear the breaking waves | Helen Sullivan

To eat an oyster raw is to eat it alive

On the oyster's edge, under the sea, on a rock, a tree root, a bamboo pole, a pebble, a tile or another shell, the bivalve's cilia - from the Latin for eyelash - are waving. Together, they move water over the oyster's gills - its shell is open, its muscles are relaxed. The oyster has lungs. It has a three-chambered heart. An hour passes; the oyster has filtered five litres of water. The oyster has listened to the breaking waves: it opens and closes according to the tides.

One valve is the cupped half of the shell, the other is the flat half. A cargo ship sounds its horn. The oyster shuts in fright.