Spider or insect?  Spiders are not insects.  They may both be tiny, creepy crawlies, but they are in fact two very different kinds of animals.

In the Rocky Mountains it is not uncommon to come across all kinds of tiny little creatures.  There are many different kinds of tiny animals in the Rockies, such as spiders, caterpillars, moths, beetles, or water bugs. They may all be tiny, but they are in fact quite different and not all of them are in fact insects.

What Makes An Insect An Insect?

Insects are a class of invertebrate animal.  This means that they are a group of animals that do not have backbones.  Refer to the classification system to understand what a class is or the 6 basic groups of animals.

Insects have an exoskeleton – this means that their skeleton is on the outside of their body.

They have three main body parts – head, thorax, and abdomen.

Insects have a pair of antennae on top of their head.

Insects have three pairs of legs.

What Are Spiders – Arachnids?

Spiders are not insects, but are arachnids.  All arachnids share a number of characteristics, including:

Most of them have two body parts.

They have eight legs.

They have jointed appendages, meaning they have legs that can bend.

Finally, they are flesh eating predators.  In other words they are all carnivores and eat other tiny creepy crawlies.

Spider Or Insect – How Are Similar?

Both spiders and insects are invertebrates, meaning that they do not have a backbone.

Both have an exoskeleton.

Spider Or Insect – How Are They Different?

Number of legs – this is one easy way to tell them apart.  Spiders and all arachnids (including scorpions and ticks) have eight legs.  On the other hand, insects only have 6 legs.

Number of body parts – in theory this should be another easy way to tell them apart, but it can be hard because they are so small.  Spiders and arachnids have only two body parts.  Insects all have three body parts.  Look closely at an ant and you can see the three parts – head, body or thorax, and abdomen.