You’ve probably heard of the octopus, an eight-tentacled wonder. Recently, science has debated whether octopuses (or octopi) are actually the descendants of alien lifeforms that landed on earth many million years ago, probably on a meteorite. The rationale lies in part behind mysterious proteins that make up the octopus — proteins not found in any other form of life on earth. Scientists may never find the proof they need to settle that one, but octopuses are some weird creatures, and that’s a fact.
In addition to their eight tentacles -from which they take their name- octopuses have three hearts. Not a single three-chambered heart, but three separate hearts. The reason why lies in the composition of their blood.
Human blood contains a substance called haemoglobin, commonly spelled hemoglobin, which transports oxygen around the body via the bloodstream. Octopus blood instead features copper-rich haemocyanin (hemocyanin). Haemocyanin functions in the same way as haemoglobin, but is a less effective carrier of oxygen. For this reason, creatures who use haemocyanin as an oxygen transport within the bloodstream require additional cardiac power. Creatures like these — octopuses, scorpions, tarantulas, and horseshoe crabs, to name a few — rank among the most ancient on earth.
And because octopus blood contains haemocyanin, it’s blue, where human blood, containing haemoglobin, is red. Some say that human blood is blue in the body, but that’s a myth.
In octopuses, three hearts give the necessary boost to their cardiac system. One of their three hearts — known as a systemic heart — functions like a human heart, circulating blood around the octopus’s body. With eight tentacles that can reach twenty feet in length in the largest octopus species, the octopus’s systemic heart has its work cut out! Meanwhile, the other two hearts work as branchial hearts, pumping blood to the octopus’s gills. Octopuses, as underwater creatures, use gills to extract oxygen from the water in order to breathe.
Consider this, as well. The mantle, a muscular structure designed to hold and protect the octopus’s organs, does exactly that — contains all of the organs, from the three hearts to the brain to the anus, in a small portion of the octopus’s body. The size of the octopus’s only rigid component, its beak, determines the size of the smallest opening the octopus can fit through — eight tentacles, three hearts, and all. And, if it’s a Pacific giant octopus, all nine brains. These giants — the same octopuses with twenty-foot tentacles — have one central brain and eight smaller clusters of nerve cells, brains that each control one tentacle.
So how’s that for size? Even without the recent scientific data about octopus proteins, writers, artists, and thinkers over the centuries have always seen octopuses as alien wonders. Just look at the myth of the Kraken. Krake, by the way, is German for octopus, although the “real” Kraken may have been inspired by the giant squid. Giant squids, by the way, can grow to nearly fifty feet in length and have three hearts, like all other members of the octopus-squid family. No doubt these creatures, known scientifically as cephalopods, will continue to terrify and fascinate humankind for many years to come.