Every night for weeks, a male leopard seal slips off the ice and sings underwater for hours. He’s not howling like a wolf or groaning like a whale. He’s doing something a bit more strange—something that, according to scientists, sounds structurally like a human nursery rhyme.
Researchers just published a study in Behaviour showing that leopard seal mating songs share an uncanny similarity to classic children’s tunes. It’s familiar in form, not in sound. Repetition, pattern, predictability—just delivered by a 300-kilo seal in total darkness.
Using entropy analysis (a method for measuring how predictable a sound pattern is), scientists found that seal songs land squarely in the same range as “Twinkle, Twinkle, Little Star” and “Humpty Dumpty.” Not in melody or pitch, leopard seals produce high-pitched trills and pulsing hoots, but in structure. Each song repeats familiar patterns in just the right way to feel almost sing-songy, in a haunting, underwater sort of way.
And they do this for up to 13 hours a night.
Why Do Leopard Seals Sing Songs?
Every season, from late October through early January, the males head below the ice and launch into their set. Each seal sings his own version of the same sounds, sticking to a specific order. He sings to be noticed, to sound familiar, and to avoid getting ignored in a sea of sameness.
Marine biologist Tracey Rogers, who recorded the seal songs back in the ‘90s, used a quad bike to reach sleeping seals, marked them with dye, then returned after dark to record them in the water. The researchers used those tapes to analyze the rhythm and repetition in each call.
Each song is a system. The rhythm, the repetition, the predictability—it all serves a purpose. The more stable the pattern, the more likely it is to carry, to be remembered, and to mean something to the right listener.
Why this matters isn’t just scientific curiosity. Structured song in mammals is rare, and understanding it helps researchers study cognition, communication, even evolution. Plus, if these guys are remixing “Rockabye Baby” beneath the Antarctic ice sheet, it’s probably worth figuring out why.
Or at the very least, adding it to your next ambient sleep playlist.
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