I knew sundown was coming Sunday night and I wanted an hour among nature's setting, experiencing the wild complexity of the Upper Peninsula. I walked down a long slowly sloping hill, a lawn as well kept as a fairway. The cedar thicket to my right, on the edge of the lawn, would withstand any human attempt to pass through it. Passing over a slight ledge, I found my pace slowed by a blanked of crushed dolomite and marsh grass. I began monitoring my hair and open skin for black flies. I was once quick and reflexive enough to swat black flies dead as soon as one landed on my skin and began biting. When I reached the shore, a flock of ducks twenty feet out in Horseshoe Bay started to swim south. A threesome of the same species of ducks took flight from a stretch of shallow water ten feet away. Startling so many animals made me feel like a bad naturalist, but only a good Native American tracker could walk on dolomite rubble without raising a crunch.
Walking the rocky shoreline, I first noticed a pair of crawfish claws on the rocks. Then I noticed a full, bleached exoskeleton amongst rocks a few feet away. Then I noticed more. I wondered why the remains of a crayfish die-off littered the shore? Then, I remembered the phenomenon of molting. Crayfish have to molt numerous times, especially when young. Seeing all those exoskeletons left on the rubble meant the water quality was good and food in the bay was plentiful. Crayfish cannot tolerate much water pollution.
Crayfish molting is made easier by biochemistry. An organ called the gastolith absorbs calcium, pulling it out of the tight shell.
When the weakened shell splits, the new exoskeleton begins to harden and the gastrolith releases calcium for its formation. The process from exoskeleton splitting to new exoskeleton completion leaves the crawfish very vulnerable. Surely naked crayfish makes a tasty dish for a gourmet.
Sometimes, I am appaled by the weakness of my science education, which didn't cover the life and characteristics of any animal half as well as the Wikipedia. My life as a natualist has been held back. I would have learned so much by seeing a molted exoskeleton as a young naturalist.