Photo: Marcia Rubin
Your narrator (left) and John Pogacnik photograph a freshwater sponge, Spongilla lacustris, in shallow waters of the Grand River. John is a biologist for Lake Metroparks, and one of the finest field naturalists that I know. An outing with him is always sure to produce a bonanza of interesting finds, and I was long overdue for a Pogacnik expedition. His and others discovery of the odd freshwater sponges, as reported HERE, spurred me to arrange yesterday's Grand River exploration. We were also joined by photographer Marcia Rubin; check some of her work out HERE.
I have never been much for jazzy LL Bean-style field clothes, especially on aquatic forays. Such wear is expensive, and I'd just destroy it in fairly short order. If the weather is warm and the water nice, I prefer shorts, an old shirt, and sandals for my creek wading. And wade we did, probably covering two miles or more of river bottom sloshing.
Photo: Marcia Rubin
Of course, one can pay a price for the comfort of sandals. We had just exited the stream after our last trek, and popped into a streamside store at the campground whose owners had kindly allowed us access to their property. I was talking to the lady behind the counter, when I looked down and noticed my feet were bleeding rather profusely. We politely excused ourselves, and went outside to make photos of the leeches that were busily wolfing down my hard-earned blood before I dealt with them.
Leeches, which are segmented worms (I don't know which species these are but will look into it, of course), can cause fairly prolific localized bleeding. To encourage unfettered blood flow, the animal releases a powerful anticoagulant. Their bites are not painful, and it takes a big one 15 minutes or so to become fully sated, at which point it detaches and drops off. If you're in the water the entire time, you may well never know what bit you, until you see the bloody wound later.
John's theory is that powdered dancers seek objects that can float for extended periods to lay their eggs on, as this is a very efficient way to migrate to new locales and thus expand their range. This maple leaf, which was moving downstream with the current, might end up a mile or so downstream before it lodges against something and the dancers' eggs hatch. Such a tactic is an incredibly effective way of ensuring that the species rapidly colonizes an entire stream corridor. The powdered dancers seem to be the most advanced of the damselflies in regards to "rafting migration".
All of these dancers were but a small part of the assemblage of animals and plants that we found, and I'll try and share some of the other finds later.