Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Skeleton
open-in-new
<p>A skeleton is the <a href="/facts/Structural_frame/4tyfPn2J">structural frame</a> that supports the body of most <a href="/facts/Animal/4b8J33nd">animals</a>. There are several types of skeletons, including the <a href="/facts/Exoskeleton/Wlmru4GW">exoskeleton</a>, which is a rigid outer shell that holds up an organism's shape; the <a href="/facts/Endoskeleton/UlLveJL0">endoskeleton</a>, a rigid internal frame to which the <a href="/facts/Organ_(biology)/FUYsLaxz">organs</a> and <a href="/facts/Soft_tissue/cHBwqLpP">soft tissues</a> attach; and the <a href="/facts/Hydroskeleton/uJ8uludK">hydroskeleton</a>, a flexible internal structure supported by the <a href="/facts/Hydrostatic_pressure/GYu6ljQ0">hydrostatic pressure</a> of <a href="/facts/Body_fluid/RkAXIBVN">body fluids</a>. </p><p><a href="/facts/Vertebrate/tT54FSTT">Vertebrates</a> are animals with an endoskeleton centered around an <a href="/facts/Axial_skeleton/mNCwdBkw">axial</a> <a href="/facts/Vertebral_column/Nuw1kV7o">vertebral column</a>, and their skeletons are typically composed of <a href="/facts/Bone/kwJaR6IQ">bones</a> and <a href="/facts/Cartilage/vxy2qzKN">cartilages</a>. <a href="/facts/Invertebrate/3CyqCVnN">Invertebrates</a> are other animals that lack a vertebral column, and their skeletons vary, including hard-shelled exoskeleton (<a href="/facts/Arthropod/JKJLTFzp">arthropods</a> and most <a href="/facts/Mollusc/1elgknsQ">molluscs</a>), plated internal shells (e.g. <a href="/facts/Cuttlebone/4gLB4CnG">cuttlebones</a> in some <a href="/facts/Cephalopod/80GlMxHG">cephalopods</a>) or rods (e.g. <a href="/facts/Ossicle_(echinoderm)/ebkmVeTe">ossicles</a> in <a href="/facts/Echinoderm/j2rd8qwt">echinoderms</a>), hydrostatically supported body <a href="/facts/Body_cavity/cPMtaaeC">cavities</a> (most), and <a href="/facts/Sponge_spicule/tVKvhqID">spicules</a> (<a href="/facts/Sponge/E9T2WFWA">sponges</a>). Cartilage is a rigid <a href="/facts/Connective_tissue/mal3fc7k">connective tissue</a> that is found in the skeletal systems of vertebrates and invertebrates. </p>