|Image from Indiana Natural History Survey|
The Wartyback Mussel (Quadrula nodulata) inhabits deeper rivers in the Upper Mississippi system, such as the Ohio River. There’s no real mystery to the origin of its name; it has bumps all over its shell. It hangs out in sand or fine gravel, where it filter- feeds by sucking in water and digesting anything somewhat nutritious. The gills do double duty as both strainers and breathing apparatuses.
Mussel reproduction is weird. The female will hold eggs in her gills3, which are fertilized when the male’s sperm are drawn in as the females are siphoning water. The female then creates a prey mimic, which looks like some sort of minnow, and as a fish comes by to eat it, larvae are released. Parasitic larvae4. I can’t find if the Wartyback uses the lure, but seeing as the main hosts are catfish, it seems likely. The larvae aren’t harmful to the fish, but, like burrs from a plant, hitch on (in this case, to the gills) to get away from mom and dad, where there’ll be less competition and more genetic dispersal.
Because they filter so much water, pollution is the major problem facing freshwater mussels. Yes, we’re talking about the whole group. I started talking in generalities about a paragraph and a half ago. Dam construction and pretty much anything that messes with river flow also add to the problem of endangerment.
The Columbus Zoo, in conjunction with people like ODNR and OSU recently built an entire center on freshwater mussel conservation. Granted, the Wartyback doesn’t seem to be listed on the site, but anything that’s good for freshwater mussels is good for the Wartyback. Breeding programs have extra steps when dealing with mussels, since they need to catch and parasitize fish and then release them. The fish likely swim away wondering what on earth just happened to them.
1Does anyone want a “Save the Wartyback Mussel” t-shirt2? Just comment and I’ll make one.
2I’d make an Ohio Lamprey plush toy if I had any idea how to do so.
3At a science convention I went to, someone’s project was counting the eggs of local mussels. I think the numbers were in the hundreds for each individual. I couldn’t help feeling sorry for her, and I was counting roadkill snakes.
4Not co-endangered, because there are plenty of catfish to go around.