Internal Anatomy

Nervous system comprised of brain, sympathetic system and a nerve cord. Brain is the coalescence of three ganglia. Various antennae and eyes are the sensory system input. Sympathetic nervous system comprises suboesophagul ganglion and a number of secondary ganglia that innervate the digestive tube (Felgenhauer 1992).

Respiratory system is varied between decapods, but is mostly comprised of gills that sit at the base of the thoracic appendages. These gills are protected in a branchial chamber, and are of foilaceous shape. Water flows through the gill systems via currents created by secondary maxilla acting as a pump (Felgenhauer 1992).

The circulatory system is open. The heart is a contractile dorsal tube, which propels blood from the back to front. Arteries branch into arterioles that run into sinuses from which the liquid in circulation (haemolymph) provides oxygen (Felgenhauer 1992). The style of circulation requires completely watertight integument, as provided by the carapace.

Digestion occurs via a compelx stomach, consisting of a gastric mill which is divided into two parts (Felgenhauer 1992, Vonk 1960). Stomach extends into middle intestine and is accompanied by a large hepate pancreas. Digestion is extracellular, but chemical processes take place mainly in the middle intestine.