Feb 17, 2020
I’m always finding new commensal animals in S. Yellow Jacket. I think I spotted rotifers feeding on ants. I am sure they’ve been here all along, they are so small, I must have missed them earlier. I was tinkering around backlighting the pitcher with a flashlight, and there they were!
Rotifers are microscopic animals found in freshwater around the world. They range in size between 0.5 mm to 0.1 mm, which means they are around the size of the blobs (mites) in the pitcher (around 0.5mm). https://en.wikipedia.org/wiki/Rotifer
The blobs are already a challenge to video, I’m not surprised I missed an even smaller and faster subject. In fact, if I hadn't been tinkering with the flashlight, I surely would have missed them. If you look at the dead insects on the pitcher’s surface, the pencam light glare obscures everything beneath the surface. Focus on the wasp in the center of the picture. With the pencam lights, you can see a few mites. But turn off the pencam lights and turn on the backlight and a mass of microscopic mayhem appears! The wasp is surrounded by hundreds of even tinier thinner blobs. These blobs are also rapidly swimming in the pitcher water, too. They are way too fast to be mites, that's for sure. They certainly look like the pictures of rotifers from Google searching.
Note the 3 mites on the wasp in the center of the picture.
The rotifers in this video are in this pitcher.
Not sure why I identified this as S. Leucophylla in my initial post instead of S. Yellow Jacket. They aren't hard to tell apart. One is 4 inches tall and yellow vs over 2 foot tall and purple.