Forest Invertebrates
Written by Chris Ann Urquhart, entomologist
Illustrations by Rebecca Mooy
THE FOREST ECOSYSTEM
A forest is a complex ecosystem made up of both living things such as trees and birds,
and non-living things such as fallen logs, water and rock. The living parts of forest
ecosystems form dynamic commun-ities whose composition changes over time as a result of
interacting and living together. Some bacteria are so small they are not visible to the
naked eye.
All living things in the forest are part of a huge, complex and interacting web of
life. Each living thing has its role in the health and growth of a forest.
State Forests scientists research how changes in the forests (from logging, fire and grazing) affect animals. This information helps
foresters better manage State forests for the conservation of the many species of
wildlife.
INVERTEBRATES
Trees give a forest its overall structure but the animals that have the greatest
influence on the health and appearance of the forest are invertebrates. Invertebrates are
animals without backbones; countless millions live in the forest, from the soil below the
leaf litter on the forest floor to high in the canopy.
The enormous variety of invertebrate animals include predators, that prey on other
invertebrates; scaven-gers, that feed on dead animal and plant material and are vital in
recycling nutrients through the forest and herbivores, that feed on fungi and living
plants. All these in turn are food for birds, fish, reptiles, mammals and even some
plants.
 Although they are so important in the forest ecosystem, most invertebrates are small,
well hidden, or beautifully camouflaged and therefore easily missed. A closer look at leaf
litter, under rocks, logs and bark, in foliage and flowers will reveal many interesting
creatures. A few of the many types of invertebrate, which may be encountered in the
forest, are:
PLATYHELMINTHES (Flatworms)
Flatworms are flattened, slimy, worm-like, unseg-mented animals from
2-30 cm in length, often with interesting colour patterns; a few have shovel-shaped heads.
They are carnivores, feeding on animals such as slugs and earthworms, and can be found
under logs or the bark of trees. (Place mouse over images for description)
 MOLLUSCA (Slugs and snails)
Native slugs and snails range in size from a few millimetres up to about
10 cm in length. They do not generally eat living plants; most feed on fungi and decaying
plant material, and a few are carnivorous. They may be found under rotting logs, in leaf
litter, and in foliage.
 ANNELIDA (Earthworms and leeches)
Earthworms range from a few millimetres up to 3 metres in size. They feed on dead plant
matter and burrow in the soil and help to recycle nutrients through the ecosystem. Leeches
are bloodsuckers, and live in foliage or on the forest floor while waiting for a meal to
come past.
ONYCHOPHORA (Peripatus or velvet worms)
 These rarely seen creatures were once thought to be a "missing link" between
worms and arthropods. Their purple to brown skin looks like velvet and they have about 15
pairs of legs. They are carnivorous and feed on other small invertebrates. They are found
only in moist forests, under logs, rocks and leaf litter
CHELICERATA (Includes spiders, scorpions, ticks and mites)
 This
group of animals usually has four pairs of legs and a body divided into two parts, the
head/thorax and the abdomen. They are found in most habitats throughout the forest.
Spiders, scorpions and most other Chelicerata are predators; ticks feed on the blood of
vertebrates and some mites are parasitic.
CRUSTACEA (Slaters and landhoppers)
 Landhoppers (amphipods) are found in moist areas in leaf litter, where they feed on dead plant matter. They are
less than 1 cm long, narrow and light coloured; when disturbed, they jump erratically,
making them highly visible in the litter. Slaters (woodlice, isopods) are flattened grey
animals under 15 millimetres long. They also live in moist leaf litter and under rocks and
logs, feeding on decaying plant material and fungi.
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