During a recent research expedition in Monterey Bay, scientists from MBARI’s Biodiversity and Biooptics Team happened upon a rare sight: a seven-arm octopus (Haliphron atlanticus). In nearly four decades of ocean exploration, MBARI has encountered this large deep-sea octopus just four times.

During a research expedition with the remotely operated vehicle (ROV) Ventana on November 6, Senior Scientist Steven Haddock and researchers from MBARI’s Biodiversity and Biooptics Team happened upon a rare sight approximately 700 meters (2,300 feet) deep in Monterey Bay: a seven-arm octopus (Haliphron atlanticus). The sighting marked our fourth observation of this species in nearly four decades of ocean exploration.

Using a 4K camera specially developed by MBARI engineers for deep-sea exploration, the team collected detailed observations of the animal’s appearance and behavior. This individual, believed to be a male about the size of a football, was clutching a crimson red helmet jelly (Periphylla periphylla). Previous research by Haddock and collaborator Henk-Jan Hoving first revealed that this species of large deep-sea octopus feeds on gelatinous animals. This new sighting underscores the complexity of deep-sea food webs and their surprising connections.

Learn more about the seven-arm octopus.

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