invertebrates
or ‘mini-beasts’
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Mayfly Nymph |
Invertebrates, invertebrates,
invertebrates... there are so many different types of these small
creatures, so called because they have no backbone. We are interested
in the freshwater dwelling invertebrates that you would find in
a river, stream, lake or pond. These are known as freshwater aquatic
invertebrates. Some people fondly call them mini-beasts and if you
look at one close up you might be able to see why!!
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Adult Dragonfly |
Invertebrates adapt to their
surroundings finding a place to live that suits them and their environment.
Invertebrates living in fast currents tend to be flattened or streamlined
so that they offer little resistance to the flow of water. These
creatures cling on to rocks, stones or sunken logs with hooks or
suckers. Some of them hide in crevices and so avoid swimming; some
caddis flies weight themselves down with stones. Others will make
good use of the conditions, the caseless caddis larva for example
cleverly spins an underwater web and waits to see who drops in it!
You might make a tunnel if you
are a creature who lives buried at the bottom of a pond or river.
The midge larva makes a tunnel in the mud by sticking grains of
mud together. To improve the flow of water and therefore oxygen
through the tunnel the midge larva waggles its body.
What if you can live in and
out of the water, why not take your own supply of air up and down
with you? The water boatman does this by trapping bubbles of air
in the tiny hairs around its body. The water scorpion and rat-tailed
maggot both use snorkels for their oxygen supply. Of course you
don’t need to be streamlined, you can become big and powerful
like the dragonfly nymph.
The 'Mini-beast Identification
Sheet' (B06b)
will come in useful when you visit a river, stream, pond or lake
to do a ‘Mini-beast Biodiversity Survey’ (B06c).
Wildlife can be plentiful near rivers and ponds because water is
so important for survival. Next time you are near a river, stream,
pond or lake think of all the tiny creatures which are going about
their lives underneath the surface, it's a hive of activity!
Click on the Mini-beasts below
to see what they look like.....
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