(HOST) Moonlight is a guide for some of Earth’s creatures, who depend on it as a signal to spawn or a way to find food during nighttime foraging, as commentator Ruth Page points out.
(PAGE) My first thought when the moon is large and brilliant is of its beauty. That leads to thoughts of all the romantic connections it has in song and story. But the moon is practical, too, not only to humans out walking on nights when it’s so brilliant it lights landscape or seascape, but to other creatures.
We’ve all seen videos of people scooping up grunion, the fish in California that beach themselves in summer by the thousands. They spawn on the coast just a couple of nights after a full moon or a new moon. Horseshoe crabs, whose eggs are vital to the lives of many migrating birds, mate on the Atlantic coast in full or new moons in May or June. Moths have been seen traveling in moonlight on low jet streams, often flying many miles in the friendly night-light.
The African dung beetle, without whom that continent would be up to here in dung from elephants and other massive animals, steer to the rich food source by whatever moonlight is available. National Geographic says they don’t use the moon directly, but depend on its polarized light. The moonlight strikes molecules of air that scatter the light into planes pointing in various directions. They make a grid of polarized light that guides the beetles.
I’ve always wondered why the beetles, after making balls of dung as big or bigger than themselves, always turn around and push a ball to the nest with their hind legs. They walk backward with their heads down, rolling the ball backwards. You’d think they had no way of knowing where they’d end up. But they’re smarter than they look: The head-down position allows the parts of their eyes sensitive to the light to see the sky. They can keep that ball of fecal material going in a straight line to their goal, without bumping into anything,
including other dung beetles traveling backwards.
Dung balls at the nest feed the beetles, providing all the nutrients they need. Females can lay eggs in a dung ball, knowing that when the young hatch, they’ll be surrounded by food.
Researchers wondered what the beetles do on nights when there’s no moon. By experimenting, they found the beetles don’t forage for dung, but steal each others’ dung balls in the dark.
We used to hear stories of psychotic people reacting in various ways to a full moon, and I’ve had acquaintances tell me they’re restless on full-moon nights. I love seeing a full moon, but I find it soothing, peaceful, reassuring; never disturbing.
When we spent summers on the Jersey shore years ago, we loved the full-moon high tides that pulled the shore waves right up under our cottage on stilts. Hear the water lapping right under your window? Delicious.
This is Ruth Page in Shelburne, Vermont.