Anatomy of a Bug

A kid once answered the question, “What is a skeleton?” this way: “A skeleton is an individual with the inside-outside and the outline.” So maybe we can define a bug like this: “It’s an animal with the inside-outside and the inside in.”

Bugs are all described as “exoskeletons” – their skeletons are on the exterior- they’re invertebrates.

This exoskeleton is composed of a hard substance called “chitin,” which shields the bug inside and checks the bug from draining out. This exoskeleton is split into jointed sections, each of which has pairs of appendages like wings, legs, antennae, etc. Bugs tend to be pretty elastic because they are full of joints. Specialists call the whole group of them “arthropods,” because their legs, “pods,” are jointed, “arthro.”

Bugs are extremely small, so it’s challenging to get a complete picture just by staring at them, but you can better understand their joints by noticing some of their first cousins like lobsters and crabs. A lobster is jointed all over, not just the legs but also the entire body and antennae.

Most bugs are jointed in their bodies too. And their bodies are split into three parts: thorax, head, and abdomen. The bulk of them has their thoraxes separated into three parts: each having couple of legs and a pair of wings on the second and third parts of the thorax.

Their heads carry a pair of antennae, jointed, of course, and two sets of eyes (minimum), one set being a couple of bubbles made up of many eyes. And generally, a mouth, which has jaws moving sideways, not up and down.

Complex! Yet so small! And so old! Way more than 74,000 years old. More like 370 million years! Humans have been walking the earth, only a tiny fraction of that time.

And many! Nature must undoubtedly love bugs because it made so many of them. About 900,000 species of them are known and presumably three or four times as many yet undiscovered. They make up about 80% of all existing animals. But they aren’t everywhere. Not in the deep oceans and hardly any in polar regions or hot springs. But I think we all agree: there are plenty.

But where they are, they are everywhere! Being so small, they can utilize and often take over many crannies and nooks in the forest, the jungle, the garage, the basement, the bed, the pantry, etc.


Bug body is divided in three parts:

  • The head of a bug is where the primary receptor parts are situated. You will find the eyes, mouthparts constituting the biting parts and mouths, and a pair of antennae.
  • The thorax, or mid-section, typically holds the wings (if the bug can fly), usually two pairs (for a total of four wings) and three sets of legs (for a total of 6 legs). The thorax is also the central location of the more dominant muscles used in operating the bug’s wings and legs.
  • The abdomen makes up the last and probably the most recognizable part of the bug. This section of the body stores the bug’s digestive system, reproductive organs, and sting organs.

That’s the bug, overall. But there’s a lot, lot more. And then many various kinds. And oh, yes! The Butterfly!

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