#symphylan

So centipedes and millipedes both belong to the subphylum Myriapoda, which means 10,000 feet. Wouldn’t it be cute of they had that many? Tragically they don’t. More about that later.

There are about 8,000 known species of centipedes worldwide and 12,000 described species of millipedes, but some scientists estimate there could be as many as 80,000. Holy cow, that’s a lot of millipede friends.

As for telling them apart there are a few different ways! If you turn over a rock or whatever and it quickly runs away, it’s probably a centipede.Centipedes are mostly predators so they need to be faster to catch their prey. A millipede will likely curl up and pretend to be dead or slowly walk away. They eat decaying plant matter so they can take their sweet time getting around. Flatback millipedes look more like centipedes, but they still move pretty slowly.

Here’s a cool picture of a rolled up millipede!

Photo by Andreas Kay

Another way to tell them apart is by taking a look at the legs! Millipedes belong to the class Diplopoda, which means double foot. This is because they have two pairs of legs on each of their body segments. Here’s a photo where you can clearly see that:

Greenhouse millipede photo by thomasbarbin

Speaking of legs, the record number of legs on a millipede is 750! That’s way more than usual, though. Most have under 100. Centipedes have on average 35 pairs of legs.

And centipedes have just one pair of legs per body segment! As seen here:

Cameroon flagtail by Frupus

Another difference is that many centipedes are venomous! Centipedes are in the class Chilopoda, which means lip foot. That name refers to their modified foremost front legs that look like mouthparts and are tipped with venomous claws they use to subdue prey. This is why centipedes should be handled carefully or not at all - they can pinch you, which can be painful, although their venom isn’t harmful to people.

Here’s a great photo of the modified front legs on a house centipede:

Photo by Nicky Bay

Rather than using venom as a defense like centipedes, millipedes often discharge and gross-smelling or tasting liquid to deter predators. Some of the chemical compounds they can emit include things like hydrogen cyanide, hydrochloric acid, and others that can cause chemical burns. Yikes!

I’ve probably rambled enough but I’d like to throw out an honorable mention to pseudocentipedes (Class: Symphyla) who are also in Myriapoda but are smaller, non-venomous, don’t have eyes, and are only distantly related to centipedes. They live in soil and adults have twelve pairs of legs. They look like this:

I found two leggy boys while I was out taking pictures of flowers! Ones kinda pale, but he was wiggling! I dont think you can ID them from that far, but they were found in Northern Illinois.