Exoskeleton Function

A rhinoceros beetle can carry over 800 times its own body weight -- roughly the same as a human lifting six loaded school buses. It can do that partly thanks to a suit of armor it wears on the OUTSIDE of its body, called an exoskeleton. Nearly every insect on Earth, all one million-plus known species, relies on this same basic design.

- What an exoskeleton is made of and where it sits on an insect's body - The main jobs an exoskeleton performs - Why insects must molt to grow - How exoskeletons compare to your own skeleton

'Exo' means outside, and 'skeleton' means the hard supporting frame of a body. Instead of bones buried inside muscle like you have, an insect's hard frame is on the outside, made of a tough material called chitin layered with proteins. This creates a hardened shell called the cuticle that covers the entire body -- head, thorax, abdomen, and legs.

1. Protection: it shields soft internal organs from predators and physical damage, much like a knight's armor. 2. Support: because insects have no internal bones, the exoskeleton is the only thing holding their shape and letting muscles pull against something solid. 3. Preventing water loss: a waxy outer layer on the cuticle keeps insects from drying out, which is critical for small creatures with a large surface area compared to their volume. 4. Sensing the world: many exoskeleton surfaces are covered in tiny hairs called setae that detect vibration, wind, and touch -- essentially acting like external nerve endings.

Humans have an endoskeleton -- bones grow WITH us throughout life, so we never need to shed our skeleton to get bigger. This is one major reason insects generally stay small: an exoskeleton becomes too heavy relative to muscle strength if the animal grows too large, which is part of why you'll never see a beetle the size of a dog in nature.