Leopard slug fact sheet | Field of Mars EEC

What are leopard slugs?

Leopard slugs are large land slugs with pale brown, grey or yellowish bodies marked with dark spots and stripes. Their scientific name is Limax maximus. They are also called great grey slugs. Leopard slugs are molluscs in the group gastropods, which includes snails and slugs.

Leopard slugs are not native to Australia. They are an introduced species and the Australian Museum describes them as the largest introduced slug found in Sydney. They are now found throughout Australia, especially in urban areas, gardens and other damp places near people.

A leopard slug, Limax maximus.

Leopard slug, Limax maximus, showing the dark spots and stripes that give this species its common name.

What do leopard slugs look like?

Leopard slugs are one of the largest slugs students are likely to see around Sydney gardens. Their body is usually pale brown, grey-brown or yellowish-grey with dark spots and lines. The spots are strongest on the mantle near the head, while the tail end often has darker lengthwise stripes. The body is soft, moist and stretched out when the slug is moving.

Leopard slugs have two pairs of tentacles. The longer upper tentacles have light-sensitive eye spots at the tips, while the shorter lower tentacles help the slug taste and touch its surroundings. They breathe through a small opening called a pneumostome on the right side of the mantle.

Leopard slugs can grow up to 20 cm long.

Where do leopard slugs live?

Leopard slugs live in moist places where they can avoid drying out. During the day they usually hide in dark, damp shelters such as crevices, under pots, under timber, beneath bark, in compost areas or under garden materials. At night, or after rain, they come out to feed.

In Sydney, leopard slugs are most likely to be found in urban areas and gardens rather than undisturbed bushland. At Field of Mars Reserve, they may be seen near built areas, tracks, garden edges or other moist human-modified places, but native slugs such as the red triangle slug are more closely connected to local bushland habitats.

Leopard slugs are often found in damp suburban gardens and other moist places near people.

What do leopard slugs eat?

Leopard slugs are mostly active at night. They feed on detritus, which means dead and decaying material. Their diet can include decaying plant material, fungi, dead animal matter and sometimes other slugs. Museums Victoria notes that they prefer decaying vegetable matter to living plant material.

Like other gastropods, leopard slugs feed using a rasping mouthpart called a radula. A radula works a little like a rough tongue covered in many tiny teeth. This helps the slug scrape and grind food.

Leopard slugs mostly feed on decaying material, but they may also eat other slugs and dead animal matter.

What is the life cycle of a leopard slug?

Leopard slugs hatch from eggs rather than changing through a complete metamorphosis like butterflies or beetles. A tiny slug hatches with the same basic body shape as an adult, then grows larger over time.

Leopard slugs are hermaphrodites, meaning each adult has male and female reproductive organs. They usually cross-fertilise with another slug. After mating, eggs are laid in damp protected places such as moist soil or under objects. The young hatch as small slugs and grow into adults over time.

Leopard slugs lay clusters of eggs in damp protected places.

What adaptations do leopard slugs have to help them survive?

Leopard slugs have several adaptations that help them survive in moist garden habitats. Their soft body lets them squeeze into narrow cracks and damp shelters. Their mucus helps them glide over rough surfaces and reduces water loss as they move. Their spotted and striped pattern can also help them blend in with bark, soil, leaf litter and shadowy garden surfaces.

Their tentacles help them sense the world around them. The upper tentacles detect light and movement, while the lower tentacles help with taste and touch. Their breathing pore allows air to enter their lung-like mantle cavity. Leopard slugs also have a small internal shell hidden under the mantle, unlike snails which carry a large external shell.

Mucus helps leopard slugs move over rough surfaces and protects their soft body from drying out.

Why are leopard slugs important?

Leopard slugs help break down dead organic matter in gardens. By feeding on decaying plant material, fungi and other waste, they help recycle nutrients back into the soil. They are also part of the food web and may be eaten by birds, reptiles, frogs, beetles, leeches and other predators.

However, leopard slugs are introduced to Australia. This means they are not part of Australia’s original native ecosystems. They are best understood as urban garden animals rather than species to encourage in bushland. Students should observe them carefully, but they should not collect, move or release them into natural areas.

Leopard slugs help recycle decaying organic matter in gardens, but they are introduced to Australia.

Related fact sheets

More invertebrate fact sheets

• Invertebrate fact sheets – overview
• Gastropods fact sheet – background on the snail and slug group.
• Red triangle slug fact sheet – a native Australian land slug found in moist habitats.
• Common rough slater fact sheet – another damp-habitat decomposer.
• Earthworms fact sheet – soil animals that help recycle organic matter.
• Millipedes fact sheet – leaf-litter decomposers that live in damp places.

Habitats and ecosystems

• Leaf litter habitats fact sheet – explains why damp leaf litter supports many small animals.
• Rock and log habitats fact sheet – shows how logs, bark and rocks provide shelter.
• Eucalypt forest fact sheet – explains the local bushland habitat at Field of Mars Reserve.
• Field of Mars Reserve fact sheet – explains the reserve habitats and catchment context.

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