Parasitic Isopods

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).

Amphipods and Isopods

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).

Barnacles (Cirripedia)

The barnacles illustrated here are representative of two particular orders the stalked barnacles; Pedunculata (1 & 2) and the sessile barnacles; Sessilia (7 & 10).  Also shown are various developmental stages including nauplier larva (3 & 8), cyprinid larva (5 & 6), intermediate forms between the two aforementioned larval stages (4 &9) and post settlement juveniles (11 & 12).  Both order’s shells are comprised of carina (Ca), tergum (Te) and rostrum (R).  Barnacles feed by filtering particulate matter from the water column with their jointed appendages (not labelled).  Female reproductive organs, ovaries (Ov) are found near the base of the animal while the male penis (P) is associated with the testes (H) near the base of the feeding appedages.  The digestive system is coloured yellow.


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.

Copepods and Branchiurans

Examples of at least four different genera once grouped together within the order Copepoda.  Now these genera diverge after the class level into too sub classes Branchiura and Copepoda as sister taxa to barnacles.  Care must be taken when analysing these Subclasses relatedness as the class Maxillopoda may not be a monophyletic group.

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).

Astacus fluviatilus (freshwater crayfish)

A species of freshwater crayfish formerly common through out streams and brooks of western and northern Europe.  Dissection on the left shows the heart (central red structure) with blood vessels (also red), muscle blocks (anterior pink ovals), and Liver (brown elongate structures in thoracic cavity).  Dissection on the right shows the cardiac portion of the stomach (anterior blue structure with “T” shape in it), the pyloric section of the stomach (narrowing part of blue structure), the caecum (brown bulb immediately posterior to pyloric stomach), hind gut (long brown canal in abdomen) and again livers (paired brown structures on either side of alimentary canal.

Decapod Larvae

Different larval stages of a range of different decapods.  Because of their complex life history many of the larval stages of different taxa were originally classified together as groups of their own.  Some lobster species have over twenty different larval stages.  Examples that are of note on this chart are the nauplius (1) of copepods, the zoea (10 & 11) of crabs, and the phyllosoma (3) of lobsters.