Brachiopoda: More on Morphology

This critter "on the half-shell" shows some of the internal anatomy of a brachiopod quite well. First note the two valves or shells. All brachiopods have two shells. This makes brachiopods look superficially like bivalved molluscs (clams, oysters, etc.) However, a closer inspection shows some striking differences. Note that each shell valve is symmetrical about the midline, but the two shell valves are often unequal in size. This is unlike most clams, which have two equal valves, each of which is slightly torted and thus asymmetrical across the midline.

(Unfortunately, the source of this image is unknown to us. It is probably not derived from UCMP.
If you know the source, please let us know.)

Notice the typical brachiopod feeding structure, the lophophore curled up on the right side. The rest of the anatomy is easier seen in this schematic cross-section of a brachiopod.

A turn-of-the-century chart of brachiopod anatomy, created by the German anatomist Rudolph Leuckart, is available from theMarine Biological Laboratory at Woods Hole, Massachusetts.