Thanks to a protein that delivers oxygen to their tissues, octopuses live as comfortably in the tropics as they do in the Antarctic. Now it turns out that the protein, a blue pigment called hemocyanin, has different genetic properties in different climates.

Michael Oellermann, a biologist at the Alfred Wegener Institute for Polar and Marine Research in Germany, presented the findings last week to the Society for Experimental Biology. The research, conducted with his colleagues Hans Pörtner and Felix Mark, is part of his doctoral project.

Octopuses “evolved to become very active, so they consume a lot of oxygen,” Mr. Oellermann said. “They need very efficient oxygen transport systems.”

The researchers gathered specimens of Pareledone charcoti, a fist-size octopus that thrives in the Antarctic, then compared the properties of hemocyanin with that of species living in warmer waters. Like the iron in hemoglobin that makes human blood red, the copper in hemocyanin colors octopus blood blue.