| THEY
HAVE/ARE |
| Bilaterally symmetrical |
| Large and complex lophophore
|
| Calcareous bivalve shell
enclosing all of the body except stalk |
| U-shaped gut |
| Open blood system with
heart |
| Sexes are usually
separate |
| Marine |
|
 |
|
 |
These are commonly known as
the lamp shells. There are about 26 000 fossil species dating from the Cambrian onwards, but only about 350 species
survive today. Externally they are similar to the bivalve molluscs, see Terebratulina caputserpentis left. The pedicle or ventral valve is usually larger than the brachial or dorsal valve (see right). All living species are
less than 10 cm long, though fossils can reach 30 cm long. They attach to the surface by a stalk or pedicle, usually in a position to gain maximum benefit from the water currents. Their chaetae are used to act as filters, and they feed mainly on detritus and algae. They are found from intertidal to 7 500 m deep in cool-temperate - cool regions. |
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Stonehaven, Scotland
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