By Sally Thorsteinsson, UNE Discovery

Photo credit: Schizoform.  Backyardbuddies.org.au

When we go out insect collecting with students in their school yards, we often find earthworms. Although they are not insects, we still bring them inside for a short time as they are fascinating to look at under the microscope. We can see their intestine, full of soil, running down the length of their bodies. We can see their segments, and how they stretch out and scrunch up to move along. We can see that they do not have bones, but they do have a hydrostatic skeleton, which they can pump fluid into to move along. They do also have muscles, and tiny bristles on the outside of their bodies, which can grip into the soil to help them move. When you hold a worm, run your finger gently along its side and you will feel the segments and the tiny bristles. Watch it wriggle on your hand, but return it carefully to the soil so it doesn’t dry out. (As Dr Jane Goodall’s mum encouraged her to do when she wanted to take a worm to bed with her as a one year old!! Dr Goodall grew up to make a huge contribution to biology and conservation – her fascination with living things obviously began early!)

If that wasn’t fascinating enough, earthworms have a brain, and a nervous system, and five hearts! They evolved from aquatic worms, and have no lungs, instead they breathe through their skin. Neither do they have eyes (they don’t really need them underground); but they do have light-sensitive tissues near their head to enable them to detect whether it is daytime or night-time. We are used to seeing them when we dig in our gardens, and they have many benefits to the soil. Their movements aerate and break up the soil, and by ingesting leaves and organic matter, they increase nutrients and mix the soil.

The earthworms in our gardens may be introduced species, but there are over 1,000 species of worm native to Australia, including one that is 3m long. Imagine finding that in a schoolyard!

References

Australian Earthworms – The Australian Museum

Earthworm Heroes – ABC Education

Mackinnis, Peter. Australian Backyard Naturalist

Remembering Dr Jane Goodall’s science and her humanity – ABC listen