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| The mandibles and their accompanying muscles are well
developed, each with a flat, crushing molar surface and a cutting edge
or incisor surface. The mandibles are capable of crushing small molluscs
and other shelled animals, and the incisor processes can cut and shred
larger items of food. The anterior rim of the oesophagus forms a
triangular flexible labrum with a thin cuticle; it is moved by a complex
set of muscles. The anterior surface of each mandible fits closely
against the labrum and together they close the mouth. A pair of soft
paragnaths is situated immediately behind each mandible (Dall
et al., 1990).
The maxillules are small, flat and curved to fit closely below the mandibles. These are followed by the maxillae, each of which has a similar set of inner basal plates (protopod) with dense, fringing spine-like setae. One part of the maxilla undulates rhythmically in a narrow channel in the anterior branchial chamber, driving a current of water backwards over the gills (Dall et al., 1990). |