How big is Giant Earthworm? | Scale of the Universe

The giant Gippsland earthworm, Megascolides australis, is one of the largest earthworms known. Adults are on average about 1 meter (3.3 feet) long, and the longest found, as of 2026, measured about 2 meters (6.6 feet). It lives only in a small area of South and West Gippsland, in the Australian state of Victoria.

Size

An earthworm has no fixed length. Its body stretches and contracts like a concertina, and depending on whether it is stretched or relaxed, a worm's length can easily double. For that reason, scientists treat weight as a more reliable measure of size. Adults weigh about 200 grams (7 ounces) on average, and the heaviest found weighed up to 400 grams (14 ounces).

Some reports describe giant Gippsland earthworms more than 3 meters (10 feet) long. Beverley Van Praagh, a scientist who has studied the worm for 30 years, considers those reports exaggerated. They may come from worms that were measured while stretched.

Size comparisons

An average adult is a little more than half the height of a person 1.7 meters (5 feet 7 inches) tall. The longest ones found were longer than that person is tall.
The common earthworm, Lumbricus terrestris, is the largest earthworm in Britain and Ireland, at 12–30 centimeters (5–12 inches) long. An average giant Gippsland earthworm is 3–8 times as long.
An average adult is about as long as four basketballs lined up in a row.
A newly hatched giant Gippsland earthworm, 20–30 centimeters (8–12 inches) long, is already as long as an adult common earthworm.

Discovery and habitat

Railway surveyors found the first known specimen in the 1870s and at first took it for a snake. Frederick McCoy, director of the National Museum of Victoria, described it as a new species of earthworm in 1878.

The worm is found in an area of about 400 square kilometers (150 square miles), and only in scattered pockets of moist clay soil within it. Colonies are found mainly on creek banks and steep, south-facing slopes. The worms live in burrows from close to the surface to 1–1.5 meters deep, and they come above ground only when heavy rain floods them out. One way to find a colony is to listen for the gurgling sound the worms make as they move through their wet burrows.

A slow life

Some earthworms lay up to 1,000 egg cocoons a year. The giant Gippsland earthworm produces a single large cocoon, 4–9 centimeters (1.6–3.5 inches) long, that holds one young worm. The young worm takes about a year to hatch and may take several more years to become an adult. In a protected environment, some have lived for 10 years.

Its slow breeding, fragile body and limited ability to move mean that a colony cannot recover easily when its soil is dug up, dries out or floods. As of 2026, the species is listed as Vulnerable by Australia's national government and as Endangered in Victoria.