There was a time when the brachiopods ruled the world's oceans - at least in the filter feeding role- but they were decimated by the Great Permian extinction. It used to be thought that the brachiopods were outcompeted by the bivalve molluscs after that event, but analysis of the fossil record shows ebbing and flowing of both phyla. Certainly the bivalve molluscs seemed to recover faster than the lamp shells. The fossil record contains over 12,000 brachiopod species but only around 330 are alive today.
The brachiopods gain their common name of lamp shell from a fancied resemblance to old Roman oil lamps. They do possess two hinged valves like the bivalve molluscs, but unlike the clams, whose shells are left and right of the animal in the brachipods the valves are dorsal and ventral. Another major point of difference is the possession by the brachiopods of a specialized feeding organ, the lophophore. This is ciliated and in its simplest form is somewhat shaped like a horse shoe. The cilia create a current which brings food onto the lophophore from which it is removed and passed to the mouth.
Brachiopods seems to be distasteful to most predators and to humans. However In Fiji and Japan the stalked brachiopod Lingula is often eaten so some are edible. In New Zealand's Fiordland brachiopods can be found at high densities on the near vertical wall of the Fiords and that was where most of these photographs were taken.
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Ryan Photographic - Brachiopoda - Lamp Shells
