The seven-arm octopus, also known as the blob octopus, does, in fact, have eight arms. One’s just a little sexier than the others. Photo: MBARI
There are a lot of weird animals living in the ocean that we know almost nothing about. One of them is called the seven-arm octopus named (as you can probably guess) for the fact that it appears at times to have seven arms instead of the regular eight. It is not called a septopus, though, because it does have eight. It can be pretty huge, too — up to 165-ish pounds — but since it lives where we can’t, we’ve only ever seen one alive a few times in four decades of hunting for them. A little over a year ago, though, researchers from the the Monterey Bay Aquarium and Research Institute (MBARI) shot some amazing footage of a seven-arm octopus.
The octopus, which is known to scientists as haliphron atlanticus and to laypeople as the blob octopus, was spotted with a remotely operated vehicle (ROV) called Ventana. The ROV was being piloted in Monterey Bay at nearly 2,500 feet deep when scientists watching the cameras saw something they had to look twice at. In 40 years of scouring the deepest reaches of Monterey Bay, this was only the fourth time anyone had seen a blob octopus.
They were using a 4K camera that was developed by MBARI engineers specifically for this kind of thing, and it paid off in spades.
“This extraordinary octopus was clutching a crimson red helmet jelly (Periphylla periphylla),” researchers wrote. “Previous research… first revealed that this large deep-sea octopus feeds on gelatinous animals. This new sighting underscores the complexity of deep-sea food webs and their surprising connections.”
Interestingly, these octopuses (no, it’s not octopi) do, in fact, have eight arms. It’s just that one of those arms is used for something a little more x-rated. “As is typical of octopuses, male Haliphron atlanticus have a specialized hectocotylus arm for transferring sperm during mating,” MBARI explained. “They tend to keep this arm tucked into a sac beneath their right eye, giving the appearance of only seven arms.”
