This chart appears to place a copepod (1) with parasitic representatives of the order Isopoda. The Suborder Cymothoida and some other Isopod families parasitise as ectoparasites grazing on mucus and skin or as endoparasites sitting in the mouth/pharynx of a fish collecting food. this chart shows some common body forms. note how the legs are repeated at each segment compared to those of amphipods which are modified for different tasks on different segments (2-8).
Arthrostraca was an order that included all species of Isopods and Amphipods because of their superficial similarities. This combination of two groups was retained within a newer classification scheme as Edriophthalma and a sister taxa Mysidacea which have since been rejected in favour of the order Peracarida which encompasses all members which were previously in these two groups. This chart shows the nervous system (blue), circulatory organ of the open blood system (pink), alimentary canal (yellow), digestive glands (orange) and brooding eggs under flattened segments of limbs (grey circles in 2 & 6).
The stomatopoda are group of crustaceans called mantis shrimp although they are distinct from shrimp and named mantis for their shared appearance with terrestrial mantids. They are predatory animals which often ambush from burrow or, less often, actively track and hunt prey. Prey capture uses very fast moving front appendages typically shaped into a barbed spear or a blunt club, the latter of which can create shock waves similar in nature to those produced by snapping shrimp. This chart shows the external (1) and internal (2) features of an adult. The colours represent different systems including the circulartory (red), reproductive (green) and digestive (yellow). Larval stages are also shown (5-7) which may remain pelagic for up to three months.
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).