Endoskeletons and Exoskeletons

If the skeleton is internal, such as in mammals, it is called an endoskeleton. This means that the skeleton is on the inside of the body.

If the skeleton is external, such as in woodlice, beetles or crabs, it is called an exoskeleton. Exoskeletons have a hard outer shell.

Image depicting that endoskeletons are in the body and exoskeletons are out of the body

Endoskeleton = Enter In = Inside = Internal

Exoskeleton = Exit = Outside = External

NOTE:

Animals can have an internal (endoskeleton) or an external (exoskeleton) skeleton, or none at all.

Examples of endoskeletons

Image showing humans and dogs have endoskeletons

All humans have an endoskeleton, and so do dogs.

Image of a shark has an endoskeleton

Sharks also have endoskeletons, but these are made of cartilage and not bone. Cartilage doesn’t preserve as well as bones, which means that fossil records are limited.

Further examples of animals with endoskeletons:

Fish, birds, reptiles, amphibians and mice all have endoskeletons

Examples of Exoskeletons

Insects, arachnids, crustaceans and mollusks have exoskeletons