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Speaker 1: Welcome to brain Stuff production of iHeartRadio. Hey brain Stuff,

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Speaker 1: Lauren bog obamb Here. Let's start with the basics. Millipedes

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Speaker 1: are not worms, nor are they insects. Insects have six legs,

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Speaker 1: and obviously millipedes have many more. But exactly how many

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Speaker 1: more The answer may vary by the particular specimen in question,

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Speaker 1: but it's never going to be nine ninety four. It

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Speaker 1: turns out that no one chose their name millie meaning

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Speaker 1: a thousand, and pedes referring to feat as a way

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Speaker 1: to convey the precise number of legs. These organisms have

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Speaker 1: their cousin, the centipede, with the prefix centi meaning a hundred,

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Speaker 1: are similarly named by way of illustration, not precision. Millipedes

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Speaker 1: fall within a subphylum of arthropods. All arthropods have in

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Speaker 1: common a hard exoskeleton, segmented bodies, and jointed legs, like arachnids, insects,

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Speaker 1: and crustaceans. What distinguishes millipedes is that they have many

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Speaker 1: segments in their body, and for each segment, they have

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Speaker 1: two pairs of legs instead of one pair, as you

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Speaker 1: would see with say, centipedes having so many legs as

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Speaker 1: part of what makes millipedes so adaptive. Fossil evidence suggests

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Speaker 1: that millipedes were among the first ever terrestrial animals, which

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Speaker 1: means they've been around for about four hundred million years.

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Speaker 1: Back in the Coniferous Period, about three hundred million years ago,

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Speaker 1: a millipede species known as arthur Plora grew to an

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Speaker 1: enormous six and a half feet long and one and

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Speaker 1: a half feet wide that's about two meters by a

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Speaker 1: half a meter. Today, millipedes range in size, thank goodness,

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Speaker 1: from just a tenth of an inch or three millimeters

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Speaker 1: to about eleven inches or a third of a meter.

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Speaker 1: So far, researchers have discovered about twelve thousand species on

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Speaker 1: every continent except Antarctica, but estimate that there could be

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Speaker 1: as many as eighty thousand species here in the United States,

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Speaker 1: every state has some species of millipedes that are unique

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Speaker 1: and can't be found anywhere else. Scientists have developed new

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Speaker 1: imaging techniques that use u VY light to help them

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Speaker 1: differentiate between millipede species. This approach works because millipede exoskeletons

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Speaker 1: and reproductive organs glow under u VY light, as is

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Speaker 1: the case with many other arthropods like scorpions. Some species

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Speaker 1: of millipede in California, however, are bioluminescent, which means they

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Speaker 1: glow in the dark. Millipedes feast on leaf litter that's

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Speaker 1: plentiful around the world. This means millipedes spend most of

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Speaker 1: their time in soil, under leaves and rocks. And what

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Speaker 1: makes them so effective at getting around in this dense

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Speaker 1: habitat is there many mighty legs. They use the first

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Speaker 1: segment of their body like a bulldozer, and having so

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Speaker 1: many legs means they have a lot of power with

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Speaker 1: which to push burrowing through the dirt. When millipedes hatch,

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Speaker 1: they have only a few pairs of legs. Then, just

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Speaker 1: like many other arthropods like crabs and spiders, they grow

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Speaker 1: through a process called molting. This process involves shedding their

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Speaker 1: exoskeleton and growing a new one. Each time they do this,

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Speaker 1: millipedes also grow a new segment and therefore two new

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Speaker 1: pairs of legs. Some millipedes stop molting when they reach adulthood,

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Speaker 1: and others molt their whole lives, which is on average

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Speaker 1: about two years. So how many legs to millipedes have

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Speaker 1: it depends on the group, but it ranges between twenty

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Speaker 1: four and seven hundred and fifty at most, though that's uncommon.

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Speaker 1: Most millipede species have under a hundred legs. Millipedes have

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Speaker 1: some defense mechanisms, but they don't bite or sting. They

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Speaker 1: have very poor eyesight. Some species have no eyes at

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Speaker 1: all and mostly just use their antenna to find their way.

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Speaker 1: A millipedes best move when it feels threatened is to

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Speaker 1: curl up in a ball and secrete chemicals that ward

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Speaker 1: off predators. The chemicals they secrete vary, but are released

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Speaker 1: in such tiny quantities that they're generally not hazardous to humans.

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Speaker 1: Some research describes how in certain tropical regions, monkeys actually

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Speaker 1: seek out millipedes and use the chemicals they secrete as

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Speaker 1: mosquito repellent. Centipedes, by contrast, can bite using small things

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Speaker 1: that do secrete venom. Even then, while a centipede bite

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Speaker 1: can be painful, it usually won't cause other harmful effects.

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Speaker 1: If you're looking to tell the difference between a centipede

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Speaker 1: and a millipede, legwise, centipedes legs tend to spread out

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Speaker 1: to their sides, while millipedes legs point downward. Centipedes only

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Speaker 1: have one pair of legs per segment, while millipedes have

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Speaker 1: two pairs. If you're not keen on getting close enough

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Speaker 1: to check, observe the creature's behavior. If it runs away quickly,

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Speaker 1: it's likely a centipede. If it just curls up, it's

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Speaker 1: probably a millipede. Today's episode was written by Danielle Duez

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Speaker 1: and produced by Tyler Clang. Brain Stuff is a production

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Speaker 1: of i Heeart Radio's How Stuff Works. For more on

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