A few days ago we were sent one of the most pleasantly simple and straightforward questions we have ever received: “How long can an earthworm grow?” This isn’t necessarily an easy question to answer, but we happen to have researched the matter before, so we can give fairly precise information about the length that earthworms can reach. And so, without further ado, exactly how long can earthworms get?
We should begin by pointing out that large earthworms are not particularly rare. Many of us have probably seen fairly long worms – perhaps about 7-8 inches (18-20 centimeters) in length – after it has rained or digging around in the garden, and in fact we’ve answered questions about huge earthworms before. One particularly large species of earthworm that is also quite common is the Lumbricus terrestris, which are native to Europe but are now found around the world, including in the United States. These creatures routinely reach lengths of about 10 inches (25 centimeters), although they can be nearly twice this size in rare instances.
Glossoscolex giganteus and Megascolides australis are more exotic earthworms that can reach even greater lengths than the Lumbricus terrestris. The former are found in Brazil and are often over three feet (about a meter) in length. The same is true of the latter, which are found in Australia, although a Megascolides australis worm can get far larger, growing to the incredible length of about 10 feet (three meters) in some cases. As we pointed out in our article about earthworm sizes, this is large for any animal, much less an earthworm.
And with that we have provided a short answer to a short question. Earthworms can grow quite long; in extreme cases, they can be up to 10 feet long, although these creatures are of course rare. As far as common earthworms go, they can grow to be about a foot long (30 centimeters), and one likely won’t ever encounter anything longer.