There is much we don’t know about the depths of the oceans. But it is home to an astonishing amount of life, holding enormous amounts of biodiversity and biomass. Now research has revealed that one of these mysterious ocean dwellers, the seven-arm octopus, chows down on jellyfish and then might be using the stinging tentacles to catch more prey.
Cephalopods are among some of the largest creatures to live in the open ocean, with the obvious exception of marine mammals and some open water fish. Because of this, they often play a pivotal role in the diet of many an ocean creature, from sperm whales to swordfish to other squids. But because of their size, they are also fairly major predators, themselves.
Yet living in the depths of the oceans, away from the prying eyes of curious marine biologists means that little is known about the habits of deep-sea cephalopods. So when researchers from the Monterey Bay Aquarium Research Institute captured video footage of the elusive seven-arm octopus holding strange gelatinous blobs in their mouths, they were fascinated.
While the jelly itself is not particularly nourishing, the arms of the creatures and reproductive organs contain plenty of calories. And it seems that the seven-arm octopus knows this. They found three different individuals snacking on the jellies, with gelatinous remains being held between the arms of the octopuses, as reported in Scientific Reports.
However, it also seems that the sneaky cephalopods may not only be eating the jellyfish, they may also be dismembering them and then using the severed stinging tentacles to their own advantage. The researchers think that they could be using the trophy tentacles either as protection from other predators, or even to hunt other fishes.
While this may sound fairly extraordinary, it is not without precedence. The blanket octopus is known to carry severed Portuguese man of war tentacles around with it, while argonauts – cephalopods that live in paper-thin shells – are frequently found hanging around jellies, in effect using them as their own personal bouncers.
The seven-arm octopus (Haliphron atlanticus) is a true giant of the deep. The second largest octopus species in the world, they can reach up to 4 meters (13 feet) in length and weigh an impressive 75 kilograms (165 pounds). But they seem to have a penchant for preying on the simple jellyfish. It might seem like there is nothing much nutritious about jellyfish as they drift around the ocean, but they are eaten by a plethora of animals, large and small. The enormous leatherback turtle, for example, seems to manage just fine surfing the oceans snacking on cnidarians.