The vampire squid (Vampyroteuthis infernalis) genome has been sequenced and found to preserve a squid‑like chromosomal arrangement, suggesting it retains genetic features of the common ancestor of squids and octopuses from about 300 million years ago. Published Nov. 27 in Science, the genome is roughly 11 billion base pairs — nearly four times the human genome and the largest cephalopod genome sequenced so far. Researchers used PacBio long‑read sequencing on a single specimen collected as bycatch in the West Pacific; the species’ rarity prevented additional samples. The result offers a crucial window into cephalopod evolution and underscores how challenging it is to study these deep‑sea animals.
Scientists Sequence Vampire Squid's Massive Genome — A 'Living Fossil' Reveals Deep‑Sea Evolutionary Secrets
Scientists have sequenced the genome ofthe vampire squid and discovered its chromosomes still resemble those of squids and cuttlefish, suggesting it has changed very little in millions of years. . | Credit: Solvin Zankl/Alamy
Cephalopod evolution has long puzzled scientists: how did squid-like ancestors give rise to today’s octopuses? New genomic data from one of the ocean’s most enigmatic inhabitants — the vampire squid (Vampyroteuthis infernalis) — provides a surprising piece of that puzzle.
In a study published Nov. 27 in Science, researchers report they sequenced the genome of a vampire squid and discovered that its chromosomes retain an arrangement more similar to squids and cuttlefish than to modern octopuses. Because the species sits on the octopod lineage but split from other octopods very early, its genome offers a window into the ancestral genomic architecture of cephalopods roughly 300 million years ago.
How the Study Was Done
Researchers obtained a tissue sample from a single animal collected as bycatch during a research cruise in the West Pacific Ocean. Using Pacific Biosciences long‑read sequencing (PacBio), they assembled the vampire squid’s genome and compared it with genomes from other cephalopods, including the argonaut (Argonauta hians), the common octopus (Octopus vulgaris) and the curled octopus (Eledone cirrhosa).
Major Findings
The vampire squid genome spans approximately 11 billion base pairs — nearly four times the size of the human genome — making it the largest cephalopod genome sequenced to date. Unlike modern octopus genomes, which show extensive reshuffling and chromosomal mixing, the vampire squid’s chromosomes preserve much of an ancestral, squid‑like layout. In effect, the species is genomically conservative, leading researchers to describe it as a "living fossil."
"It’s nice to have resolved why vampire squids retain so many ancestral, squid-like traits," said Bruce Robison, senior scientist at the Monterey Bay Aquarium Research Institute, who was not involved in the study.
Why This Matters
The genome gives scientists a rare look at the ancestral chromosomal organization of cephalopods and helps explain why some features of the vampire squid resemble ancient relatives. It also provides a foundation for future studies on cephalopod development, neurobiology and adaptation to deep‑sea environments.
The research underscores the practical challenges of studying vampire squids: they live at depths that are difficult to access, are solitary and rare, and do not survive well in captivity. Because only a single specimen was available for sequencing, additional samples will be needed to understand population variation and confirm certain findings.
Background
Discovered in 1903, the vampire squid was first mistaken for a cirrate octopus because of webbing between its arms. By the 1950s scientists placed it in its own order, Vampyromorphida, recognizing that it is neither a typical squid nor a typical octopus and noting its cloak‑like appearance.
This new genome sequence is a landmark for cephalopod biology: it not only reveals surprising evolutionary connections but also provides a rich resource for future comparative genomics and studies of deep‑sea life.
