Exoskeleton

The head of an ant: Chitin type

An exoskeleton supports and protects an animal's body from outside and not like the internal endoskeleton - of, for example human beings - from inside.

Many invertebrate animals (such as shelled mollusks) have exoskeletons in the sense of external hard parts. But if one speaks of an exoskeleton one mostly means that of arthropods (i.e. insects, spiders, myriapods and crustaceans).

Exoskeletons contain rigid and resistant components that fulfil a set of functional roles including protection, excretion, sensing, support, feeding and (for terrestrial organisms) acting as a barrier against desiccation. Exoskeletons first appeared in the fossil record about 550 million years ago, and their evolution has been seen as critical as a driving role in the Cambrian explosion of animals that took place after this time.

The exoskeleton ( exoskeleton suit) is a device intended to restore the lost motion functions of a person or other living being. The exoskeleton also serves to increase human muscle strength and range of motion by means of an external skeleton and drive elements.

Exoskeleton Media

Discarded exoskeleton (exuviae) of dragonfly nymph
Exoskeleton of cicada attached to a Tridax procumbens (colloquially known as the tridax daisy)
Borings in exoskeletons can provide evidence of animal behavior. In this case, boring sponges attacked this hard clam shell after the death of the clam, producing the trace fossil Entobia.
cicada exoskeleton