One of the world’s largest worms might escape notice, if not for the loud gurgling noises that can be heard coming from underground as the species burrows and squelches through its moist clay.
The giant Gippsland earthworm, a purple and pink colossus that lives in a small, wet patch about 100km east of Melbourne in south-east Australia, reportedly stretches as long as 2 to 3 metres.
These slow-moving and graceful giants, according to species specialist Dr Beverley Van Praagh, are quite unlike the “squiggly and squirmy” garden variety, which Guardian readers crowned UK invertebrate of the year in 2024.
Even an average sized individual would eclipse the UK’s largest recorded specimen, a 40cm-long lob worm named Dave found in a Cheshire vegetable patch.
Worm researchers such as Van Praagh say it is challenging to study an animal that lives underground, even one so immense.
She said the main way to detect them was to stomp about on the surface, and listen out for the distinctive sound – like water draining from a bath – of a startled worm retracting deeper underground.
Sometimes researchers look for evidence of burrows, complex tunnels with rippled sides, according to Simon Hinkley, the collection manager of terrestrial invertebrates at the Museums Victoria Research Institute.
They might find a cocoon, shaped like a cocktail sausage, where the worms laid a single egg that produced one large baby – about 20cm long – after a year. Egg cocoons were a beautiful amber colour, he said. “And if you hold them up to the light, you can actually see there’s one worm inside.”
Extreme care has to be taken when digging, as these are vulnerable creatures.
If you accidentally nick a giant worm it bleeds, and is unlikely to survive, Hinkley says. Anecdotal accounts describe “horrific” scenes of fields running “red with blood” when the worm’s habitat was first cleared and ploughed.
The gentle giants remain in small, isolated colonies, but as a long-lived species that produce few young, and continue to be threatened by changes to the water table, soil disturbance and excavation.
Dr Pat Hutchings, a senior fellow at the Australian Museum, said Australia had a huge diversity of worms, including many endemic species and several giants found on land, in sand and under the sea.
Hutchings specialises in sea worms, known as polychaetes. She described one large specimen, measuring at least 1 metre long, found in sediments under shallow waters about 180km north of Sydney.
The species was named Eunice dharastii after the fisheries scientist Dr Dave Harasti, who managed to entice the iridescent worm out of its underwater tube by dangling an offering of fish head over the burrow.
Hutchings said another sea worm species, found in the Kimberley region of northern Australia, was long enough to be slung around her neck like a feather boa.
Hutchings said even though worms might be gathered together as one group of animals, they were incredibly diverse in their forms, behaviour and reproductive strategies.
“We’ve got this amazing biodiversity in Australia,” she said, including thousands of worm species. There just weren’t enough worm scientists yet to describe them.
Invertebrate of the year 2025
The Guardian is asking readers to nominate species for the second annual invertebrate of the year competition. Read more about it and make your suggestions here or via the form below.
