Worms fact sheet | Field of Mars EEC

What are worms?

Worms are soft-bodied invertebrates with long bodies and no backbone. The word worm is a common name, not one scientific group. It can describe many different animals, including segmented worms, flatworms, roundworms, leeches and other worm-like invertebrates. Worms live in soil, leaf litter, rotting wood, freshwater, wetlands, estuaries and the ocean. Some are easy to see, while others are microscopic.

Around Field of Mars Reserve, worm-like invertebrates can be found in damp soil, leaf litter, under logs, near creeks and in other moist sheltered places.

A blue planarian flatworm is one of many soft-bodied invertebrates commonly called worms.

Giant Gippsland earthworms are very large annelids found only in a small part of Victoria.

How do you know it is a worm?

Worms are usually soft, narrow and flexible. They may stretch and contract, glide on mucus, swim, burrow or loop their bodies to move. Worms do not have the body plan of insects. They do not have six true legs, antennae or a hard outer skeleton. Snakes and lizards have backbones and scales, slugs and snails are molluscs with a muscular foot, and centipedes and millipedes are myriapods with many legs. Caterpillars may look worm-like, but they are insect larvae.

Blue planarian flatworms are predators that move through damp leaf litter and soil.

Worm groups

Worms are easier to understand when they are grouped by body type and habitat.

Segmented worms – annelids

Annelids are segmented worms. Their bodies are divided into many ring-like sections. This group includes earthworms, marine bristle worms and leeches. Earthworms burrow through soil using muscles and tiny bristles called setae. They breathe through their moist skin and feed on dead organic matter and soil. Marine bristle worms, also called polychaetes, are mostly found in marine environments and often have many bristles along their bodies.

Many marine annelids are bristle worms with fine bristles along their segmented bodies.

Flatworms and planarians

Flatworms have soft, flattened bodies. Some are parasites, but many planarians are free-living predators. Land planarians, such as blue planarian flatworms, can appear after wet weather in damp leaf litter and garden areas. They move on a slime track and may hunt small invertebrates such as slaters, millipedes, snails or other worms. Some planarians are well known for their ability to regenerate body parts.

Sulphur-coloured planarians are colourful flatworms that live in damp places such as soil, leaf litter and under logs.

Leeches

Leeches are segmented worms, but they look and move differently from earthworms. Most true leeches have a sucker at each end of the body and do not have the tiny bristles found on many other annelids. Leeches live in freshwater, wet forests and marine habitats. Some suck blood, while others are predators or scavengers that feed on small animals.

Leeches are segmented worms that use suckers to grip surfaces and move through damp habitats.

Roundworms and other worm-like animals

Roundworms, or nematodes, are usually tiny unsegmented worms. Many live in soil, freshwater or marine habitats. Some feed on bacteria, fungi, algae or other nematodes, while others are parasites of plants or animals. Gordian worms, also called horsehair worms, are another worm-like group. Adult gordian worms are long, thin animals often found in still water, while their young stages live as parasites inside insects or spiders.

Some animals have “worm” in their common name but are not true worms. Velvet worms, for example, are worm-like animals in their own phylum, Onychophora, and are more closely related to arthropods than to annelids.

Roundworms are usually microscopic and live in moist soil, freshwater or marine habitats.

What is the life cycle of worms?

There is no single worm life cycle. Earthworms and many leeches produce eggs inside protective cocoons. Planarians may lay egg capsules, and some can also reproduce by splitting and regrowing. Roundworms hatch from eggs and moult as they grow. Gordian worms have aquatic adults, but their young stages live inside insects or spiders. Many young worms look like smaller adults, but some have life stages that are very different from the adult form.

Earthworms and many other worms hatch from eggs or cocoons.

What adaptations do worms have to help them survive?

Worms have many adaptations for life in hidden, damp places. Earthworms use flexible segments, body muscles and tiny bristles to push through soil. Many worms have moist skin or gills that help them exchange gases. Flatworms use mucus to glide and avoid drying out. Leeches use suckers to grip surfaces or attach to food. Many worms hide under logs, stones, bark or leaf litter to stay cool, moist and safe from predators.

Tiny bristles called setae help earthworms grip the soil as they move.

Why are worms important?

Worms are important in soil, freshwater, leaf litter and marine food webs. Earthworms help break down dead material, while many roundworms help recycle nutrients by feeding on bacteria, fungi, algae or other tiny organisms. Burrowing earthworms can mix and aerate soil. Predatory flatworms, leeches and bristle worms help control small animal populations. Worms are also food for birds, frogs, fish, insects, spiders and other animals. Because many worms need moist, sheltered habitats, their presence can tell us something about the health of soil, creeks and leaf litter.

Earthworms help recycle dead leaves and return nutrients to soil.

How can you help worms?

You can help worms by protecting cool, moist and sheltered habitats. Leave leaf litter, fallen bark, stones and rotting logs in place where it is safe to do so. Plant local native plants, keep soil covered with mulch or leaf litter and avoid unnecessary pesticide use. When investigating worms, gently replace logs, rocks and bark after looking underneath. Compost worms are useful in worm farms, but they should not be released into bushland or waterways because they may not belong in local habitats.

Leaf litter and damp soil provide shelter and food for many worms.

Explore more

Worms are part of a much larger world of invertebrates. Compare worms with insects, arachnids, crustaceans, myriapods, molluscs and other animals that live in soil, leaf litter, freshwater and bushland habitats.

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