Tuesday, May 23, 2023

The case of the frightened millipede

 The Wise Woman found a flat-backed millipede, order Polydesmida, on the trail at Panola Mountain. It was handsome: 3 and a-half inches, black bands over pinkish brown. We frightened it, and it flipped over on its back as it scrambled up a steep slope. I scrambled to get a picture, but I got a photograph of only part of it.

Adult flat-backed millipedes usually have 20 sections. You can see only 16 in my photograph. The others are buried in grass and leaf litter.

After the head, the first section has no legs. Each of the next four sections has one pair of legs. Each of the remaining sections, except for the last, has two pairs of legs. (Well, males have gonopods, legs adopted for reproduction, on Segment 7.) 

If you’re curious about the “flat back,” some millipedes have a flat shell — it looks like the shell that covers a lobster tail to me — across the back of each section. In some, they hang over the body, kind of like stubby wings on a plane. Other millipedes have a kind of keel running along the back.

• Sources: The Field Museum has a clear explanation here:

https://www.fieldmuseum.org/science/special-projects/milli-peet-class-diplopoda/milli-peet-millipedes-made-easy/milli-peet-1

You can see some interesting photos here:

https://www.inaturalist.org/taxa/47734-Polydesmida/browse_photos

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