Insects are invertebrates. That means they have no backbones. They are also arthropods. That means they have exoskeletons. The exoskeleton is a hard covering on the outside of the body. Insect bodies have three sections: the head, thorax, and abdomen.

An insect’s head has antennae, eyes, and mouthparts. Antennae give the insect information. Insects have compound eyes. Compound eyes have many lenses. They may also have simple eyes. Simple eyes have just one lens. Insects have some parts of their mouths on the outside. These mouthparts are different depending on what the insect eats.

Behind the head is the thorax. Legs and wings are attached to the thorax. The muscles used for movement are here, also. Insects have six legs. All their legs have five parts. Wings come in different shapes and sizes, too. Some insects have two wings. Some have four. A few insects do not have wings at all.

The back part of an insect is the abdomen. This is where an insect digests its food and gets rid of waste. It is where its heart is. An insect heart is just a tube that pumps blood. Organs used for mating and laying eggs are in the abdomen.

Some experts think there may be as many as 10 million insect species. Some are very tiny. Some can be as long as six inches. Fossil dragonflies from millions of years ago have been found. They had a wingspan of up to 28 inches!