Last week, I was on a Fancy Adult Business Trip in Paris, France. I had a little time to explore the city before Important Business meetings, so I did something I never thought I would get a chance to do: Visit the Catacombs.
A long, long time ago, back when the educational TV channels actually had… educational programming (yes, I’m that old)… I watched a show that featured the amazing tunnels dug under the city of Paris, which had been stacked to the ceiling with the skeletons of 6 million people. The short version of the story is: Paris has been a big city for a long time, and several centuries ago, funerary practices were not very… hygienic. A few of the cemeteries became public health hazards, so beginning in the late 1700’s, the city systematically emptied every single cemetery and reinterred the bones in the abandoned quarry tunnels. And instead of just throwing all the bones in, the “architect” of the project laid the bones to rest in beautiful arrangements that honored the lives of the people who were moved. The bones are grouped together by the cemetery they were from, or later by which the battle of the French Revolution they died in.
Amazing! But I was a poor kid, we never went on vacations, and although I had big plans for the future (I was going to go to college!), I grew up knowing that people like me didn’t get to travel so the best I could do was just read every book I could get my hands on. But I seriously lucked out, and 25 years later, not only did I get to go to Paris, my work was paying for the entire trip. ! So, to the Catacombs!
It was amazing. The first 1/3 of the tunnels was just getting down. The cramped spiral staircase seemed to go on forever. Then you went down a very narrow cramped tunnel sparsely lit with old-timey lamps. That photo above should give you an idea of how cramped they were. Those shadowy figures are humans. This is definitely not an activity for somebody with claustrophobia.
Anyway, you may be wondering: Wait, aren’t you a nature blog? Why are you talking about this here???
Well. Thing is, nature happens even in the strangest, most artificial environments. When you put skeletons in human-made caves and then leave them for a few hundred years, interesting things start to happen.
-> Warning: photos beyond the cut include human remains (skeletons)
The tunnels were dug into the limestone bedrock under the city, beginning around the year 1300, and were used as a quarry for building materials. The floor and ceiling are limestone. Although the tunnels were dug by humans, they function exactly like a natural cave. I’m from Texas, another place with a limestone foundation (and *lots* of caves). The Catacombs are 20 meters underground (65 feet), and when you’re that far underground, you may think you are protected from the rain, especially after standing in line for two hours in it. You’d be mistaken. In the photo above, look at the path. The darker edges are wet.
Limestone is primarily calcium carbonate. If you have hard water, you are likely familiar with it. The white residue it leaves behind are dissolved minerals from limestone—and you can see that same residue on the bones in the photo above. In some parts of the Catacombs, the bones were glittering from crystals that had started to grow on them, and they were beautiful.
If you’re familiar with what happens when you add water to caves, you shouldn’t be at all surprised to learn that baby stalactites are forming above the bones in some areas (see below). Stalactites take thousands of years to form. One estimate I looked up said they grow less than 10 cm (just under 4 inches) in 1,000 years. If this section of the tunnel dates back to 1400, that would make these stalactites about 600 years old.
But enough about geology, right? You want to see bugs, why else would you be on my blog? I also wanted to see bugs, but I was not expecting them, and I was a little pessimistic after getting stranded in Pittsburgh, meaning I missed not only my one free day in Paris, but a chance to see a friend who moved abroad a million years ago and currently lives in Germany. While I stood in line for two hours, she had started posting her photos from the day before when she went to the Catacombs without me, so I got to see her photos of the moss growing on the rocks and her comment, “Life finds a way.”
And since I am the iNat fanatic that I am, I thought, “hmmmm I’ll bet nobody else has posted iNat observations from the Catacombs…” so I paid attention to green stuff growing so I could get a couple fun photos of moss.
The first bits of green I saw was this–it appears to be green algae [link to iNat] growing on the bones, but I am not an algae expert. Then, aha! The Moss!
A beautiful, luscious, gorgeous bed of moss [link to iNat]. Perfect. I love it. Yes, life does indeed find a way. This part of the tunnels had moss in several spots, so I hung around getting a good view of it. Then, wait, who is this!?
!!! An Isopod !!! [link to iNat] Guys, I love isopods. I love isopods so much, when I saw that in Japan, you can get an iPhone case shaped like an isopod, I dropped everything and ordered one, even though it meant I’d have to upgrade my phone and I hate upgrading my technology because I’m a dinosaur. But here they were! Yes, they. There were three in the first area I saw them. In the photo above, you can see little “chocolate” sprinkles on the rock. These babies are having a nice moss feast! The first photo of this post was on this rock face as well. I was so happy. Look at these cuties!
So we have all this algae and moss, with fat happy isopods eating it to their hearts’ content. Clearly, there was plenty of moss to go around, so what was keeping the isopod numbers in check?
I’ll give you a hint:
These guys. There were cellar and cave spiders [link to iNat] throughout the tunnels, always in close proximity to the isopods. It was fairly predictable, too. If I saw a patch of fuzzy green stuff, I could reliably find an isopod and a spider.
There are hundreds of miles of tunnels under Paris, so extensive that holding 6 million skeletons leaves most of the network completely empty. The public tour goes through only a tiny fraction of the tunnels holding human remains. Just imagine what other food webs developed in the ~700 years since these tunnels were created, which humans have never witnessed.
As I was walking towards the spiral staircase back up (it was long), I was granted a fond farewell by this lovely moth who would not hold still:
Photos from March 4, 2018 / Posted March 14, 2018