If you live on a farm or a suburban area with a backyard and spacious land, chances are, you have encountered millipedes crawling around on the ground or inside your house more than once.
These cylindrical arthropods are often mistaken as insects. But the truth is, they are closely related to invertebrates with hard exoskeletons such as shrimps, crayfish, and lobsters. Millipedes are also known as “thousand leggers” and can grow between 1 and 1.6 inches long.
With their legs, you must be wondering whether these animals can dig underground or make their way into any type of soil. To be exact, do millipedes burrow?
Millipedes are considered burrowing animals.
Their numerous legs help them dig into the soil and burrow their way into their nest for shelter and laying eggs. To know how millipedes burrow their way into the soil, we must first under how their legs work. So, let’s dive right into it.
What Makes Millipedes Legs Unique?
Contrary to mainstream belief, millipedes don’t have thousands of legs. It is estimated that there are around 12,000 species of millipedes and most species possess around 300 legs.
But in 1926, a unique discovery was made near San Bernandino, California, where they first found a species that has the most legs recorded known as Illacme plenipes. It was recorded that most Illacme possesses around 600 legs, but the one they found in California exceeded their expectation with a grand total of 750 legs.
One of the things that make millipedes different from other arthropods is their legs. If you look closer, you can find two legs for each body segment. In other words, each segment is equipped with a pair of legs.
In most millipedes, the first segment usually lacks legs, and depending on the species, the number of legs for segment two and on back might differ.
In younger millipedes, especially right after they hatch, only three pairs of legs can be found on their bodies. Most baby millipedes have three pairs of legs under six body segments. With each growth phase, they will undergo an anamorphic development process to add more segments and legs.
Once they are fully mature, you can expect these critters to have above a hundred legs on their segmented bodies.
How Do Millipedes Burrow?
To dig under the soil, millipedes will use all of their body parts. That includes their numerous small legs that provide the most thrust power when burrowing. There are three burrowing methods that happen with millipedes.
The first one is called bulldozing. To bulldoze their way into the soil, millipedes will use their head and the first segment to make the initial thrust.
In the second mechanism known as wedging, their front part will be inserted into the crack or spaces made on the soil before their legs push the rest of their body, causing the opening to widen. This will make it easier for them to repeat the whole process once the soil cracks have become larger and porous.
Finally, the third mechanism is known as boring. Similar to the drilling concept, millipedes will use the rest of their segmented bodies, especially larger ones to bore through the soil.
They will penetrate further while moving each segment and the next to become larger, allowing for more spaces to be made when they thrust forward. This mechanism is frequently used by the species with a much narrower front segment.
Where Do Millipedes Live?
Millipedes prefer to live in a moist and wet environment. As a matter of fact, you can find them under leaf litter, stones, dead wooden plants, or any sheltered areas that are protected from direct sunlight.
They will also burrow into the soil for shelters and building their nests. This is where they spend most of their time during hot seasons and when they lay eggs.
As detritivores, millipedes can thrive in most substrates.
Millipedes’ population is also higher in tropical and subtropical forests due to the low population of other prolific decomposers such as earthworms.
Are Millipedes and Centipedes Related To One Another?
At a quick glance, you might think that millipedes and centipedes are closely related to one another because of their legs. Although these invertebrates belong to the same phylum Arthropoda, millipedes belong to the class Diplopoda while centipedes belong to the class Chilopoda.
Aside from being in different classes, here are other things that make these two critters different:
- Millipedes’ bodies are much more rounded than centipedes’ bodies, which are usually flattened.
- Two pairs of short legs can be found on each segment of millipedes’ bodies. The number of legs on every species of millipede varies from 40 up to 400. Meanwhile, one pair of legs can be found in each body segment of centipedes. The number of legs for each species also varies from 15 up to 177.
- Millipedes have shorter antennae than centipedes, which usually have longer antennae. In some species of centipedes, their antennae could grow as long as their back legs.
- Millipedes aren’t poisonous critters. Meanwhile, centipedes are mostly venomous. Their first pair of legs has been modified into venomous claws to catch and kill their prey.
- Millipedes usually move in slow waves while centipedes can move sideways and backward when they want to.
- Millipedes curl their bodies to protect themselves from predators. Some species can produce smelly liquid in their defense glands known as ozopores. This liquid will be released to deter their predators away. Meanwhile, centipedes can sting their enemies with venomous bites. These venoms contain several chemical compounds such as cardio-toxins, serotonin, and histamines. In some cases, if their predators are immune to the venom, they will detach the legs caught by the predators and run away with other legs.
Overall, millipedes aren’t considered pests as they don’t bring any harm to humans or animals. In fact, if you have a farm or a small garden, these critters are beneficial to the soil and the plants.
With the aid of millipedes burrowing around and breaking down decaying plant matter, they enrich the soil with nutrients and beneficial organic materials.
But if you notice their population might jeopardize the ecosystem in your garden, you can remove all dead leaves, decaying plants, and lower the soil moisture level to reduce their numbers.