Crustacea

The Crustacea show a great morphological diversity of appendages which may be grouped into three categories, cephalic, thoracic and abdominal. Their appendages are commonly biramous (i.e. comprising two branches). Such types of appendages typically have a basal segment, protopodite, build up of two pieces - a coxopodite or coxa and a baspodite or basis.

Figure: A cyclopoid copepod, Macrocyclops albidus (dorsal view).

The basipodite carries the two "branches" that is an inner endopodite and an outer exopodite. These may have different number of segments. Some of these components may be lost; there may be processes like excite, endite, epipodite etc. of cephalic appendages.