Are Spiders Insects or Arachnids?

March 18, 2015 by  
Filed under All Posts, Reptiles

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Are Spiders Insects or Arachnids?

This is the age-old question. Even if you don’t particularly care for creepy crawlies, you most likely have, at one time or another, categorized spiders incorrectly. We are here to set the record straight.

Biologists would turn over in their graves at the responses that some people give to this question. There are many things that crawl across the ground and spiders and insects are two of them. Notice that we said two of them and not one of them. These two are in fact, different.

The True Facts About Spiders and Insects

You scream in terror. You’ve seen a spider crawl across the floor. It could be as big as a speck but to you it is five inches long with hairy legs. In your fright, you scream, “Someone kill that insect!” Hopefully no one will wait until you classify it correctly to help you out.

Here’s a quick biology lesson. According to classification methods, both spiders and insects belong to the group Arthropoda. Literally, it translates to “joint footed.” Under the Phylum Arthropoda, there are many smaller classes of animals. One class is called Insecta for “insects.” Another class is called Arachnida for “spiders.”

The Difference Between Insects and Spiders

Here are some differences that you may or may not have noticed between insects and spiders.

Let’s begin with the insects. Insects have:

  • A segmented body: head, thorax and abdomen
  • Insects have six legs – one pair on each body segment
  • Insects have wings. They either have four or two wings or even none in one group.
  • Insects have antennae. They use them to as feelers.
  • The vision of insects is sharper because they have two compound eyes.
  • Insects have quite an intricate internal system that includes a brain, a nervous system, a heart, a stomach or gut and breathing tubes referred to as tracheae.
  • Their life cycle begins as at the egg stage. They then graduate to larva, pupa and then adult.

So, what about spiders? Here is the lowdown on these misidentified creatures. Spiders have:

  • A body divided into two segments: a cephalothorax and an abdomen.
  • They have eight legs (four on each side) just like other arachnids.
  • They have eight eyes. These are simple seeing eyes so their vision is not as sharp as that of insects.
  • Spiders do not have antennae. They do have two pincers on the front that act as a mouth.
  • Spiders do not have wings.
  • Spiders have fangs to inject poison for paralysis of their prey.
  • Spiders have the ability to spin webs for catching and holding their prey.
  • There you have it, folks. Once and for all, spiders and insects may coexist together but they are not the same.

    Jasmine Hinesley is a team member at Animal-World and has contributed many articles and write-ups.

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