Octopuses Burn More Energy Changing Color Than Humans Do While Running

Researchers in the United States have found that octopuses expend more calories changing color than a human does during a 23-minute run. This groundbreaking study is the first to quantify the energy cost of the remarkable camouflage ability of cephalopods.

Kirt Onthank, a marine biologist and professor at Walla Walla University in Washington, led the research. He explained that adaptations like color change offer significant advantages but come with high energy costs for the animals. According to him, the findings shed light on the trade-offs octopuses face when camouflaging to evade predators.

How Do Octopuses Change Color?

An octopus’s skin contains specialized structures called chromatophores, which are tiny elastic pigment sacs controlled by muscles. When these muscles relax, the sacs remain compressed, and the colors are barely visible. When the muscles contract, the sacs expand, displaying the octopus’s vibrant hues.

“Octopuses have about 230 chromatophores per square millimeter of skin, which is more than the pixel density of a 13-inch 4K laptop display, which has around 180 pixels per square millimeter,” Onthank explained, emphasizing the complexity of the system.

Using their nervous system to control these chromatophores, octopuses can create highly detailed camouflage patterns or elaborate displays to communicate or defend themselves.

The Energy Cost of Camouflage

The study, published in the journal PNAS on November 18, was conducted as part of the master’s thesis of Sofie Sonner, a co-author of the research. Skin samples from 17 ruby octopuses (Octopus rubescens) were analyzed, and researchers measured oxygen consumption during the expansion and contraction of the chromatophores.

The results revealed that, on average, an octopus uses about 219 micromoles of oxygen per hour to perform a complete color change — approximately the same amount of energy it uses for all other bodily functions while at rest.

This research highlights the complexity and energetic cost of octopus camouflage behavior, showcasing how extraordinary these creatures are and how much more there is to discover about them.

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