Did you know that some of the snails found in New Zealand
streams come from overseas?
I'm one of them and I'm called Physa. My small, round shell
makes me look a bit like a bubble and you might not notice me if I'm not moving.
We Physa snails can spread quickly in streams and ponds because we can start
laying eggs when we are only ten weeks old!
I'm one of the creatures that help to clean up our streams. I do
this by eating the green slimy stuff that grows in polluted (dirty) water. The
slimy stuff can grow really quickly if there is no shade over the stream and
when people let fertiliser from farms and sewage from cites into the water.
Sometimes there is too much of this slime for us and our snail friends
Potamopyrgus to eat.
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