Today I traveled to the American Museum of Natural History to get a sneak peek at “Creatures of Light: Nature’s Bioluminescence,” the new exhibit opening on March 31st. (It’s $25 for Creatures of Light, but that includes access to the rest of the Museum and the Rose Center. A Super Saver gives you access to everything [all exhibitions, IMAX and the Space Show] for $33.)
After a walk through the exhibit, filled with things like an interactive swarm of virtual fireflies (see below) and real, live Flashlight Fish in a tank, we sat down with Dr. Marc Branham of the University of Florida for a short presentation on the best example of bioluminescence right in your backyard, the not-so-humble firefly.
• Fireflies are punctual. One species of firefly Dr. Branham studied always began their mating lighting pattern 28 to 29 minutes after dusk. “Not 27 minutes. Not 30 minutes. Exactly 28 to 29 minutes,” explained Dr. Branham.
• A firefly’s butt isn’t just called a “firefly’s butt,” but a “Photic organ.” (One presumes all glowing bits of animals or plants are called “photic organs,” but I forgot to ask.)
• Firefly larvae are predatory, tracking down snails and slugs by following their slime trails, paralyzing them with a bite, then liquifying their target. And they glow to warn off the animals that would eat them that they aren’t tasty.
• Fireflies taste terrible. Branham once put a firefly he’d captured in a net gently between his lips. (Both hands were occupied opening up a sample jar.” “Both lips went numb. Then my throat constricted. They really taste sort of astringent. I quickly put them into my jar and I haven’t done that since.”
• “You find more fireflies over lawns in poor parts of town than affluent parts of town.” Branham hasn’t done any hard research, but suspects this happens because poor people use less herbicide and fungicide on their lawns.
• There are different shades of firefly glows. “All fireflies that can flash have a color that is pre-adapted to the time of night that they flash,” said Dr. Branham. One current hypothesis is that these colors evolved to provide the most contrast to the particular time of the night sky against which the fireflies are broadcasting.
• In the ichthyology department at the AMNH, there’s a Wi-Fi network named “Ceviche”. (That’s technically not about fireflies, but I thought it was amusing.)
• “Firefly flashing has evolved multiple times in the family.” Moreover, bioluminescence has evolved several times independently over the millennia.
• Fireflies aren’t swarming much these days. “Over the last 15 years we’ve seen a drop in firefly numbers. And we don’t know why,” said Dr. Branham. “We don’t see these high population densities [that swarm].”
• Female fireflies judge males by their glowing acumen. “There’s something about aspects of their flash pattern that are much more attractive than others.” Different species respond to differing markers. “In one species I studied, females really liked males who could flash really fast. But there was an upper speed limit to the flash [that they found appealing].”