The cuttlefish is sort of a fashion disaster combining a master of disguise and a used car salesman. It’s stripey; it’s spotty; it’s monotone. It can shuffle patterns, blink them off and on, make them go all swirly, or hide them completely. It’s equally good at vanishing into the coral shrubberies or popping out in scintillating technicolor when a prospective mate jets past. (Got 30 seconds? Here’s YouTube evidence for swirliness; camouflage)
You could be forgiven for assuming that all this neon tomfoolery would be useless after nightfall. But Roger Hanlon, of the Marine Biological Laboratory, and colleagues make a compelling case that cuttlefish pay attention to their appearance even in the dark. They cease broadcasting to the opposite sex when they curl up for the night, but they take care to adopt a camouflaged skin pattern.
In what has to be a cool entry on their resumes, researchers followed cuttlefish using an 18-inch remote-controlled sub outfitted to record video in near darkness. The squidlike creatures paid attention to the background, altering their skin tone to blend in with nearby rocks, algae, or coral – or adopting a disruptive pattern to break up their outline. The behavior implies keen night vision in both cuttlefish and their predators, the authors note in American Naturalist; otherwise you’d expect to see less variability in their choice of sleepwear.
Most owls stay awake all night, so they tend to size each other up by sound, not sight, according to research in the same journal. Researchers Loic Hardouin, David Reby, and colleagues found that male scops owls can judge how big a rival is by how deep a hoot it can manage.
When the researchers digitally altered the pitch of recorded hoots, they found that males were more keen to swoop in and rough up shriller-sounding hooters (i.e., punier owls) than the same call pitched a little lower. Even better – when researchers lowered the pitches of the calls they played, they noticed that nearby owls tried to deepen their own voices, giving the impression they were burlier than they really were. Sort of the midnight version of puffing out your chest.
(thanks to the Nuthatch for the tip)