Freshwater Crayfish (Decapoda)

The freshwater crayfish genus Astacus is used to illustrate the internal anatomy of the now obsolete order Thoracostraca which comprised all shrimp, lobster and crayfish.  Internal structures are colour coded where red represents the open circulatory system, yellow the digestive system and blue the ventral nerve cord and associated ganglia.  Among the illustrations are an entire vertical longitudinal section (1), cross section through the thoracic region (2), the shape of various paired appendages (3), dorsal view of a dissected anterior region of alimentary canal (4), the network of vessels mixing the open circulatory system (5), the male (6) and female (7) reproductive organs, section of a compound eye (8) and structure of antennule with auditory structure labelled (9).