endopodite

Endopodite is a term used in crustacean anatomy to denote the inner ramus of a biramous limb. In many crustaceans the limb is biramous, consisting of a proximal protopod from which two branches arise: the exopodite (outer ramus) and the endopodite (inner ramus). The endopodite usually bears the main distal limb segments and can be composed of several articles separated by joints, with muscles enabling flexion and extension. Its morphology and degree of segmentation vary widely among crustacean groups. In decapods, for example, the endopodite forms the inner branches of the walking legs and associated appendages, while the exopodite may be reduced or specialized for other functions. In other crustaceans, the endopodite may be slender or broadened, and its segmentation can reflect adaptations for swimming, grasping, or feeding. The endopodite is contrasted with the exopodite, the outer ramus that can play roles in swimming or respiration in some taxa. The term is primarily used in crustacean morphology and functional anatomy, though related concepts of limb subdivision appear in other arthropod groups. Etymology derives from Greek endon meaning within and pous meaning foot.