A creature straight out of the abyss has rewritten what we know about octopus evolution. The mysterious 'vampire squid from hell' has just given scientists their biggest genomic surprise yet—a staggering 11 billion base pairs, making it the largest cephalopod genome ever decoded. To put that into perspective, it’s more than double the size of any other squid genome studied so far. But here’s where it gets fascinating: hidden within this colossal DNA code lies a story about the deep evolutionary links between squids and octopuses that most people have never heard.
Although its name suggests otherwise, Vampyroteuthis infernalis isn’t a squid at all. Rather, it’s a sort of evolutionary time capsule—a living relic tracing its roots back nearly 183 million years. This species stands alone as the last survivor of an ancient branch of cephalopods, clinging to existence in the oxygen-depleted depths of the ocean, far beyond where most marine life can endure.
Many researchers consider the vampire squid a “living fossil.” Despite its adaptations to deep-sea life, it still carries the hallmarks of its ancient relatives. Those links hinted to scientists that this cryptic creature might preserve vital genetic clues about the origins of modern cephalopods—before squids, octopuses, and cuttlefish split into separate evolutionary paths some 300 million years ago.
Genomicist Oleg Simakov of the University of Vienna explains it best: “The vampire squid sits right at the interface between octopuses and squids.” In other words, it’s a biological bridge, connecting the two groups through shared ancestral traits that have since diverged into their own astonishingly different forms. Studying its genome is like finding a Rosetta Stone for cephalopod evolution.
Despite its ghostly lifestyle—drifting motionless through pitch-black waters more than 600 meters (2,000 feet) below the surface—scientists managed to obtain a rare sample by chance, when a research vessel from Tokai University accidentally caught it off Suruga Bay. When researchers sequenced its DNA, they were stunned: between 11 and 14 gigabases, dwarfing even the largest genomes of known cephalopods.
For comparison, the longfin inshore squid measures 4.4 gigabases, the Hawaiian bobtail squid 4.9, and the common cuttlefish—previous record holder—5.5. Octopuses, surprisingly, have even smaller genomes. The California two-spot octopus, for instance, comes in at 2.2 gigabases, while the common octopus contains only about 2.7. This means the vampire squid’s genome isn’t just larger—it’s massive, several times bigger than that of many of its closest relatives.
But here’s the twist: around 62 percent of its genetic code is made up of repetitive DNA—endless stretches of repeated sequences that don’t directly code for new functions but inflate the genome’s sheer bulk. This mysterious characteristic might be a clue to how its genome grew so huge while remaining relatively stable over millions of years.
The research team compared the vampire squid’s genome to those of other cephalopods, including squids, cuttlefish, octopuses, and even the shelled nautilus. They also added the peculiar muddy argonaut—an octopus species whose females have a delicate external shell. Through these comparisons, a striking pattern emerged: though the vampire squid is an eight-armed “octopodiform,” it has kept parts of its chromosomes similar to those in ten-armed squids and cuttlefish, called “decapodiforms.”
What’s even more intriguing is that early octopuses seemed to share that same squid-like chromosomal layout before undergoing a dramatic reshaping process known as “fusion-with-mixing.” This evolutionary shuffle compacted and blended chromosomes, a change that may have sparked the unique intelligence and adaptability that octopuses display today. Meanwhile, the vampire squid’s chromosomes remained largely untouched—a living snapshot of what came before.
This discovery positions the vampire squid as a vital missing link, connecting modern cephalopods to their deep evolutionary roots. As genomicist Emese Tóth of the University of Vienna puts it, “The vampire squid retains a genetic heritage that predates both squid and octopus lineages. It gives us a direct window into the earliest stages of cephalopod evolution.”
The findings, recently published in iScience, challenge how we think about evolution beneath the waves. Could this ancient deep-sea drifter hold even more secrets about intelligence, adaptation, and survival? And more provocatively—if evolution once shaped such creatures in the darkness, what else might be waiting out there, still unsequenced, keeping the ocean’s oldest stories locked away?
