Endoskeleton

Endoskeleton of a swordfish

An endoskeleton is a structure that holds an animal from inside.

One can find endoskeletons in three phyla and one subclass of animals: in Chordata, Echinodermata, Porifera and Coleoidea. An endoskeleton allows the body to move and gives the body structure and shape.

A true endoskeleton develops from mesodermal tissue. Such a skeleton is present in echinoderms and chordates. The Coleoidae do not have a true endoskeleton in the evolutionary sense; here, a mollusc exoskeleton developed into several sorts of internal structure, the "cuttlebone" of cuttlefish being the best-known version. An important advantage of an endoskeleton over an exoskeleton is that the endoskeleton provides more structural support. Endoskeletons hold inner organs, tissues, and systems together easily.

Endoskeleton Media

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  A human skeleton on display at Booth Museum of Natural History

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  Fossilized skeleton of various dinosaurs

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  The skeleton of a kitefin shark, a cartilaginous fish

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  The notochord endoskeleton of Branchiostoma, a cephalochordate (lancelets)

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  The dermal ossicles of a starfish, an echinoderm

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  The silica spicule skeleton of a Venus' flower basket, a glass sponge