Featured Image Credit: MBARI
By Shelby Hoover
The elusive seven-arm octopus (Haliphron atlanticus) has been spotted by the Monterey Bay’s Aquarium’s deep diving, robotic submersible. In fact, this is only the third time that the seven-arm octopus has been spotted by the submersible in the past 27 years!
You may be wondering… “what is a seven-arm octopus”? You are not alone, very little is known about this mysterious cephalopod. Despite its name, it does, in fact, have eight arms. The eighth arm is coiled up under the cephalopods eye. This adaptation is only found in males and is used for transferring sperm! The seven-arm is also one of the largest marine invertebrates reaching lengths of 11-13 feet and can be up to 165 pounds! These octopi are very important to a healthy ecosystem and are often a food source for whales, sharks and some open water fish.
There is still much to learn about the seven-arm octopus. However, the recent footage from Monterey Bay provides scientist with crisp and clear images of the creature feeding and provides insight on what and how they may eat.
Check out the video below!
As you may have noticed in the video, the was found eating a jellyfish. It can be seen holding the bell of an egg-yolk jellyfish in its arms. (Phacellophora camtschatica)
After the recent spotting of the seven-arm octopus, scientists at Monterey Bay Aquarium Research Institute complied footage from their previous sightings. They also gathered all available specimens. Scientists found that those they had observed were holding small, gelatinous masses. Furthermore, some if the specimens had remains of jellyfish in their stomachs.
Second Sighting of the Seven-Arm Octopus. Notice the gelatinous, yellow
mass at 1:48.
Jellyfish have very few calories and do not provide a lot of energy for the octopus. This is fine for seven-arm octopus since they not very active. However, scientist speculate that they could be using the jellyfish as a tool to catch more nutritious prey.
This does not come as much of a surprise to several marine biologists. The seven-arm octopus is part of a larger group that all have some close interactions with jellies. All of the members of this group use jellyfish as defense or to catch prey. Scientists were not sure how the seven-arm octopus interacted with jellyfish… until now!