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Looking at Arthropod Structure

So what makes an arthropod? Why is it different from a mammal? Does an arthropod have a skeleton? Yes, but it's on the outside and called an exoskeleton. You might be wondering how an arthropod can get bigger if it has a hard outer skeleton. Doesn't it outgrow the shell? Yes. It has to shake off the shell and let a new one grow every now and then. When an arthropod loses one exoskeleton to grow bigger, it's called molting.

Images of Arthropods

Do arthropods have legs to move? Yes again! They have special legs that are jointed. They usually have several legs, more that the four that mammals have. Do they think? That's a tough one. They have advanced nervous systems. They even have groups of neurons that think and help the organism hunt, move around, and find a mate. Do they sit back and think about watching television? Probably not. Can they learn? Yes. Not a lot, but they can learn new behaviors. It helps them adapt to new situations.


We have one more big idea to introduce about arthropod development. Metamorphosis is a process where you change your body shape as you grow. In insects, it can be very special. There are even different kinds of metamorphosis.

All species of butterfly, skipper, and moth go through metamorphosis.

Complete and Gradual

You may have learned about caterpillars changing into butterflies. That is a complete metamorphosis. Another complete metamorphosis happens when maggots turn into flies. Complete metamorphosis means that the entire body shape has changed (wormlike into insect with wings).

The other type of metamorphosis is called gradual metamorphosis. Grasshoppers are a good example of a gradual one. They start off as small odd-shaped grasshoppers with no wings. As time passes, they molt their exoskeletons and grow wings. It's not a big change like a butterfly.

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Changing Planet: Adaptation of Butterflies (US-NSF Video)

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