Insects of Southern Australian Broadacre Farming Systems - Grains ...
Insects of Southern Australian Broadacre Farming Systems - Grains ...
Insects of Southern Australian Broadacre Farming Systems - Grains ...
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SLUGS & SNAILS (Order Pulmonata)<br />
Gastropod - gastro (stomach); pod (foot)<br />
The phylum Mollusca is divided into six classes <strong>of</strong> which<br />
the Gastropoda contains the only land-based molluscs.<br />
There are about 36 gastropod families in Australia.<br />
Main characteristics<br />
Adult and juvenile forms<br />
Gastropods have an unsegmented s<strong>of</strong>t-body that<br />
commonly has an external (or internal) calcareous shell.<br />
All gastropods have a well-developed head at one end<br />
<strong>of</strong> the foot with eyes and 1-2 pairs <strong>of</strong> tentacles. The body<br />
and internal organs are twisted back so that the stomach<br />
lays above the large fleshy foot, hence the name<br />
‘stomach foot’. Gastropods move by gliding along a<br />
surface <strong>of</strong> mucus or slime that is produced from glands<br />
on the foot.<br />
Lifecycle<br />
Most gastropods are hermaphrodites, which means they<br />
have both male and female reproductive organs within<br />
the same body. Eggs are usually laid in crevices in the soil<br />
or under rocks but some species dig holes in the soil, lay<br />
eggs into the cavern, then cover the hole with soil.<br />
Habitat<br />
Gastropods favour moist environments and are usually<br />
found under logs and rocks, in leaf litter or under tree<br />
bark during the day, and move about and forage in more<br />
favourable conditions at night. Slugs are particularly<br />
susceptible to drying out and some snails enter<br />
aestivation (shell sealed with a thickened mucus layer to<br />
conserve moisture ) to survive hotter periods.<br />
All gastropods feed using a radula, which is a tonguelike<br />
structure covered by rows <strong>of</strong> rasping teeth. Most<br />
gastropods feed on fungi, algae and dead organic matter<br />
but some can also damage young crops and pastures. A<br />
few are carnivorous and may prey on other snails.<br />
Generalised shelled gastropod<br />
Protoconch<br />
Source: Modified from Smith and Kershaw, 1979<br />
Generalised slug<br />
Body<br />
whorl Keel Mantle Eye<br />
Aperture<br />
Umbilicus<br />
Columellar<br />
plait<br />
Foot<br />
Breathing<br />
pore<br />
Source: Modified from Smith Lucid Key<br />
Tentacle<br />
SECTION 4 COMMON Pest, Beneficial AND EXOTIC Species<br />
65<br />
<strong>Insects</strong> <strong>of</strong> <strong>Southern</strong> <strong>Australian</strong> <strong>Broadacre</strong> <strong>Farming</strong> <strong>Systems</strong> Identification Manual and Education Resource © 2012
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