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Often Overlooked - The Invertebrates
It is paradoxical that the largest
group of living things on the planet is the least noticed! Despite
their numbers, many types of invertebrates are too small to be seen,
live under water or in the soil, or are otherwise camouflaged or
partially hidden where they live.
The invertebrates are
those animals which do not have a backbone or spine. This group
includes many types of animals including:
- crustaceans (crabs, crays and lobsters,
barnacles, prawns - even the humble garden slater or wood louse
is a crustacean)
- worms (flatworms, segmented worms, nematodes
and leeches)
- insects (beetles, butterflies, ants -
any bug that has wings in the adult form and six legs)
- arachnids (spiders, mites, scorpions,
amblypygids - those arthropods with eight legs)
- centipedes and millipedes
- peripatus (the Velvet Worm)
- snails and slugs, including land snails,
slugs, nudibranches (sea slugs) and marine shells
In Australia, 86,000 species of insects
have already been described. There are almost 2,000 species of spiders
in 70 families. Described segmented earthworms number 325 species
at present but it is estimated that there could be as many as 1,000
species nationwide. Even the ancient and unique Velvet Worms (which
are neither worm nor centipede) number more than 40 species in Australia
and all of these are restricted to moist environments.
Invertebrates such as
worms and slugs have a very important role to play in the ecosystem.
Like the humble mushroom, these animals help break down organic
matter and release nutrients which can then be used by other plants
and animals.
Some invertebrates may
also be important environmental indicators. We already credit amphibians
as being our "canaries in the coal mine" but a decline
of, say, land snails or aquatic insects could also be a early warning
sign that something is wrong in the environment. However, these
invertebrates aren't as showy or endearing as a frog so we don't
notice when they disappear or suffer population declines.
In this site, some invertebrates have been given
their own sections. You can read about them in:
Another site that you might like to visit is
the Australian
Museum's home page which has many links to these and other invertebrates.
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