endoskeleton A skeleton that is contained within the body. In vertebrates, the endoskeleton comprises the axial skeleton and the appendicular skeleton. In Echinodermata, the skeleton lies beneath the epidermis and technically it is therefore an endoskeleton. Compare EXOSKELETON.

en·do·skel·e·ton / ˌendōˈskelitn/ • n. Zool. an internal skeleton, such as the bony or cartilaginous skeleton of vertebrates. Compare with exoskeleton.DERIVATIVES: en·do·skel·e·tal / -ˈskelitl/ adj.

endoskeleton A skeleton that is contained within the body. In vertebrates, the endoskeleton comprises the axial skeleton and the appendicular skeleton. In Echinodermata, the skeleton lies beneath the body surface and technically it is therefore an endoskeleton. Compare EXOSKELETON.

endoskeleton A supporting framework that lies entirely within the body of an animal, such as the bony skeleton of vertebrates or the spicules of a sponge. The function of an endoskeleton is to support the body and in vertebrates it also protects the organs and provides a system of levers on which the muscles can act to produce movement. Compare exoskeleton.