Winter World_ The Ingenuity of Animal Survival - Bernd Heinrich [61]
I started walking backward toward the shore, pulling the duck with the turtle attached to its foot. The turtle would not let go. I looked into its hard yellow eye with its starred little black iris—the eye that had, scarcely unchanged, seen the dinosaurs come and go.
How could I get the turtle off? I wondered—because I was not going to let this creature finish drowning the duck. That might take hours in this shallow water. I had no weapon at hand, and contemplated slowly dragging the monster to shore and finding a stick to beat it over the head. Maybe it would then let go.
As I was thus slowly maneuvering the pair toward shore, the turtle finally obliged and let go. Now I held a duck, which still had not moved and had remained totally silent. The web between its toes was badly torn. But this injury would heal. I threw the duck into the air. It quacked a few times, and flew off.
Meanwhile the turtle slowly, ponderously, moved on the bottom out of the stirred mud into less murky water. I reached down and grabbed its long tail. I don’t know why. The engagement it had had with the duck was long enough. Ours somehow, wasn’t yet. But what to do? I lifted it—hefted it—but perhaps wisely not all the way out of the water, even if I could have, which wasn’t a sure thing. But I lifted it high enough to see its pale yellow underside—of thick neck and belly. What could I do? Nothing. I let it go—it resumed its slow lumbering journey away from the shore, toward deeper water. Perhaps I should have felt guilty—I may have deprived it of its last meal before it would fast for six months while stuck in the mud.
A year later, as the latest crop of baby common snapping turtles were digging themselves out of their nest in the gravel of my neighbor’s yard also to enter hibernation quarters in the pond, I scooped three of them up and put them into an aquarium along with minnows, whirligig (Gyrinid) water beetles, tadpoles, and one giant predaceous (Dytiscid) water beetle larva. The hatchlings seemed lively enough, but they refused all food. Instead, one became food: within a day the water beetle larva killed it by clamping its hollow pincers into the turtle’s neck and injecting digestive juices. I removed the predaceous beetle larva while it was sucking up its meal, and then left the aquarium outside.
By December the aquarium had acquired a thick layer of ice. The ice did not slow down the minnows or the beetles, which both remained as quick as before, but the turtles settled to the bottom and looked dead. I presumed that was normal, for a turtle. Finally in late December, I brought the aquarium inside and when I removed the remaining ice and pulled up the turtles, they still seemed stone-dead. However, as soon as they warmed up they became as lively as they’d been before. They were now likely smaller (lighter) since they had not yet eaten anything in the three months since hatching out. What had changed was that they were now voracious feeders, and they could only now start to grow.
Hibernating baby snapping turtle.
Perhaps hatchling snapping turtles don’t feed until after they have hibernated. If so, they are among the few creatures that normally start their life with an eight-month fast. At near 0°C, their metabolism shuts down and helps them conserve energy and/or reduce their need for oxygen. In contrast, northern fish compensate and adapt their metabolic machinery to be active despite the otherwise normally depressed metabolism due to low temperature. (Summer-active minnows that I put into ice water went belly up in seconds.) In fish, that temperature compensation involves activating new enzymes (isoenzymes) that perform the same function