Cuttlefish and Their Amazing Technicolor Dreamcoats

By Olivia Ferrari.

A person might wear their heart on their sleeve, but cuttlefish seem to wear their thoughts right on their skin.

Horst Obenhaus, a neuroscientist working with the Marine Biological Laboratory in Woods Hole, Massachusetts, is studying how these unusual creatures communicate with color. In particular, he and his team now think the unique patterns cuttlefish show on their skin while they sleep might be a colorful reflection of their inner thoughts—and, maybe, even of their dreams.

Cuttlefish are cephalopods—cousins of octopuses and squid. They’re clever animals with complex brains. Previous research has shown cuttlefish have decent short- and long-term memory and are social animals that can learn from past experiences. Cuttlefish have passed the marshmallow test, a commonly used psychological gauge of self-restraint and long-term planning. And they even experience something that looks like REM sleep, or rapid eye movement sleep. This is the phase of sleep during which humans dream. Sleeping cuttlefish have been seen moving their eyes rapidly, twitching, and altering the patterns on their skin, suggesting they might be experiencing something similar.

Even in people, sleep is a mysterious process. Scientists aren’t entirely sure why we do it. But one explanation is that sleep helps convert daily experiences into long-term memories, reactivating experiences we had while awake so that brain structures like the cortex can extract useful information. This, scientists think, helps us consolidate experiences and learn new skills.