When you think of earthworms, you probably think of tiny creatures that burrow around in your yard. However, they’re not always so tiny! Some are probably bigger than most snakes you have seen.
Of course, these earthworms are usually only found in certain parts of the world. Even if you go to those areas, you may not see them because they spend most of their time underground. However, this doesn’t change the fact that they are important parts of their ecosystems wherever they are.
Keep reading to learn more about the largest earthworm in the world!
What Is an Earthworm?
Earthworms are terrestrial invertebrates belonging to the phylum Annelida. They have segments on both the outer and inner parts of their bodies. Typically, they are found in the soil, and they eat all sorts of organic matter. This matter includes plant matter, fungi, bacteria, protozoa, nematodes, rotifers, and various microorganisms.
Generally speaking, earthworms are harmless. In fact, they are often beneficial to the soil. They break down decaying and dead organic matter so that it can be converted into rich soil. In this way, they help support the growth of plants. Additionally, the channels that they create with their movement through the soil create holes that aerate the soil and are good for drainage.
Earthworms’ bodies are very different from those of other animals. They breathe through their skin, as they don’t have any lungs. Additionally, they don’t have eyes, so they use receptors within their skin to sense touch and light. In order to pump blood through them, they have five organs comparable to hearts.
Earthworms have many adaptations that allow them to live underground successfully. They don’t have any rigid internal structures, such as skeletons, that would interfere with their movement and flexibility. They have a streamlined shape that allows them to burrow through soil.
Additionally, earthworms are segmented animals, and each one of their segments has small bristles, known as setae, that they use to essentially grip the soil while they are moving through it.
The Largest Earthworm Species in the World
Arthur Bartholomew (1833—1903) / public domain – License
The largest earthworm species in the world is the giant Gippsland earthworm (Megascolides australis). These earthworms are very rare, found only in one river valley located in southeast Australia – the Bass River Valley of South Gippsland. In the entire world, these worms can only be found in an area that totals about 150 square miles.
On average, these worms are 3.3 feet (1 meter) long and 0.79 inches (2 centimeters) in diameter. They also weigh approximately 0.44 pounds, or 200 grams. They do have relatively long lifespans compared to other worms, which can allow some of them to grow to be 9.8 feet (3 meters) long.
This giant earthworm was first found in the 1800s. Workers examining a rail line accidentally came upon one of these specimens. They actually thought that it was some sort of snake because of its size, and then they took it to a professor at the University of Melbourne. The professor confirmed that it was actually an earthworm.
Compare this to the average length of earthworms, which is closer to three or four inches, and you will see that this is truly an exceptionally giant earthworm!
The Life of the Largest Earthworm
Giant Gippsland earthworms thrive in wet subsoils of river banks that have a clay-like consistency. Humans don’t see them very often, as they usually stay in their optimal habitat, burrowing deep underground.
Their natural habitat was once the soils underneath dense forests, but the habitat is now covered by farmland. These worms have been able to survive that conversion, despite the removal of the native vegetation.
Smaller worms will come up to the surface to defecate, but these giant worms defecate underground. Of course, they don’t want their burrows filled with their own waste, so they rely on heavy rains to flush it out.
These giant worms are very sensitive to vibrations above ground. This means that if people are walking around right above them, they will move away underground. Because of their sheer size, their movement creates gurgling noises that people can actually hear from the surface.
Right now, giant Gippsland earthworms are classified as a protected species. The introduction of agriculture into this part of Australia has hurt the population of worms. Additionally, they reproduce and develop very slowly. These worms can produce one egg capsule at a time, which takes a whole year to incubate into just one offspring.
If you are ever in Victoria, you may feel tempted to dig up a giant Gippsland worm just to look at them. Even if you don’t mean any harm, this can be very harmful to them. These animals are very fragile, and handling them incorrectly could result in their deaths. The best thing you can do for these worms is to respect their habitat and leave them alone.
The Single Largest Earthworm
Paolo G/Shutterstock.com
Although the giant Gippsland earthworm is the largest earthworm species on the planet, the single largest earthworm ever found did not belong to this species.
In fact, the longest and largest earthworm was a rapper giant earthworm (Microchaetus rappi), also known as the African giant earthworm. This specimen was an amazing 21 feet (6.7 meters) long when naturally extended, and 0.8 inches (20 millimeters) in diameter. It was found on a road located between Alice and King William’s Town in South Africa in 1967.
This single earthworm is still listed in the Guinness Book of World Records as the longest earthworm ever found.
However, although the rapper giant earthworm is a large earthworm, as a species, it does not come close to the giant Gippsland worm. The average rapper giant earthworm is about 4.5 feet (1.4 meters) in length. The single specimen that broke the world record was an anomaly.
How Can Earthworms Change Their Length?
When assessing the size of the largest earthworm, scientists typically use their length when extended, rather than contracted. You may wonder, how do earthworms achieve this longer length?
Earthworms use two different sets of muscles when they move. They have circular muscles that loop around each one of their segments, as well as longitudinal muscles that go up and down the length of their bodies. The contraction of their circular muscles is what enables them to stretch, becoming thinner and longer.
When earthworms stretch underground, they use the setae to anchor the front parts of their bodies in the soil. Once the front part is set in position, they contract their longitudinal muscles and pull the rest of the body forward. They do this over and over, and this is how they move through the soil.
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