Welcome to brain Stuff production of iHeartRadio. Hey brain Stuff, Lauren bog obamb Here. Let's start with the basics. Millipedes are not worms, nor are they insects. Insects have six legs, and obviously millipedes have many more. But exactly how many more The answer may vary by the particular specimen in question, but it's never going to be nine ninety four. It turns out that no one chose their name millie meaning a thousand, and pedes referring to feat as a way
to convey the precise number of legs. These organisms have their cousin, the centipede, with the prefix centi meaning a hundred, are similarly named by way of illustration, not precision. Millipedes fall within a subphylum of arthropods. All arthropods have in common a hard exoskeleton, segmented bodies, and jointed legs, like arachnids, insects,
and crustaceans. What distinguishes millipedes is that they have many segments in their body, and for each segment, they have two pairs of legs instead of one pair, as you would see with say, centipedes having so many legs as part of what makes millipedes so adaptive. Fossil evidence suggests that millipedes were among the first ever terrestrial animals, which means they've been around for about four hundred million years.
Back in the Coniferous Period, about three hundred million years ago, a millipede species known as arthur Plora grew to an enormous six and a half feet long and one and a half feet wide that's about two meters by a half a meter. Today, millipedes range in size, thank goodness, from just a tenth of an inch or three millimeters to about eleven inches or a third of a meter.
So far, researchers have discovered about twelve thousand species on every continent except Antarctica, but estimate that there could be as many as eighty thousand species here in the United States, every state has some species of millipedes that are unique and can't be found anywhere else. Scientists have developed new imaging techniques that use u VY light to help them
differentiate between millipede species. This approach works because millipede exoskeletons and reproductive organs glow under u VY light, as is the case with many other arthropods like scorpions. Some species of millipede in California, however, are bioluminescent, which means they glow in the dark. Millipedes feast on leaf litter that's plentiful around the world. This means millipedes spend most of
their time in soil, under leaves and rocks. And what makes them so effective at getting around in this dense habitat is there many mighty legs. They use the first segment of their body like a bulldozer, and having so many legs means they have a lot of power with which to push burrowing through the dirt. When millipedes hatch, they have only a few pairs of legs. Then, just like many other arthropods like crabs and spiders, they grow
through a process called molting. This process involves shedding their exoskeleton and growing a new one. Each time they do this, millipedes also grow a new segment and therefore two new pairs of legs. Some millipedes stop molting when they reach adulthood, and others molt their whole lives, which is on average about two years. So how many legs to millipedes have it depends on the group, but it ranges between twenty four and seven hundred and fifty at most, though that's uncommon.
Most millipede species have under a hundred legs. Millipedes have some defense mechanisms, but they don't bite or sting. They have very poor eyesight. Some species have no eyes at all and mostly just use their antenna to find their way. A millipedes best move when it feels threatened is to curl up in a ball and secrete chemicals that ward off predators. The chemicals they secrete vary, but are released in such tiny quantities that they're generally not hazardous to humans.
Some research describes how in certain tropical regions, monkeys actually seek out millipedes and use the chemicals they secrete as mosquito repellent. Centipedes, by contrast, can bite using small things that do secrete venom. Even then, while a centipede bite can be painful, it usually won't cause other harmful effects. If you're looking to tell the difference between a centipede and a millipede, legwise, centipedes legs tend to spread out
to their sides, while millipedes legs point downward. Centipedes only have one pair of legs per segment, while millipedes have two pairs. If you're not keen on getting close enough to check, observe the creature's behavior. If it runs away quickly, it's likely a centipede. If it just curls up, it's probably a millipede. Today's episode was written by Danielle Duez and produced by Tyler Clang. Brain Stuff is a production
of i Heeart Radio's How Stuff Works. For more on this in a multitude of other topics, visit our home planet how stuff Works dot com for more podcasts. For my heart Radio because the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows,