Wednesday, July 3, 2013

Are there Clams in Michigan?

By Amy Derosier, Wildlife Action Plan Coordinator, DNR Wildlife Division

Yes, we really have clams in Michigan. We just call them freshwater mussels. These strange critters are nature’s water purifiers. They are
filter-feeders, which means they feed by straining tiny food from the water, just like many whales do but on a much smaller scale. Because of the way they feed, they can tell us a lot about the quality of our streams. They are reliable indicators of water pollution problems and other environmental health concerns. They are also a key link in the food chain – they eat tiny algae and bacteria and are then eaten by animals like mink, otter, raccoons, turtles and birds.
Mussels have an interesting life history that relies on fish. Mussel babies are called glochidia, and they need to attach to the gills or fins of a fish host to complete their life cycle. Freshwater mussels have unique ways to attract just the right type of fish to play “babysitter” to their young. They have evolved body parts that resemble small fish, crayfish, worms or insects. Fish see these “lures” as dinner and bite at them, at which point the mussel releases its glochidia so that they have a better chance of attaching on to the right host fish. Some mussels even grab ahold of the fish’s head. And remember – these critters don’t even have eyes!

The glochidia spend from a week to a few months attached to the fish
before dropping off to live at the bottom of the stream or lake for the rest of their lives. They don’t hurt the fish in any way. Many mussels live for 20-30 years, but some can live longer than 50 years. Mussels reproduce in mid to late summer. Look for them at this time and you just might be able to see one of these amazing lures,

See a video of a mussel lure in action – we have these same mussels in Michigan.

Or check out this video of a mussel grabbing a fish – we have these same mussels in Michigan too:

How are they doing?
In North America we have nearly 300 species of freshwater mussels, compared to 12 species in Europe. In Michigan we have 45 species that can be found in streams, rivers and lakes. Unfortunately, over half of Michigan’s freshwater mussels are in trouble and considered endangered, threatened or species of special concern.