The genetic blueprint of the vampire squid (Vampyroteuthis sp.) ranks among the most substantial in the animal kingdom, surpassing 10 billion base pairs in length.
The vampire squid (Vampyroteuthis sp.) is one of the most enigmatic animals of the deep sea. Image credit: Steven Haddock / MBARI.
This creature, often referred to as a ‘living fossil,’ inhabits the abyssal zones of all global oceanic basins, typically found at depths between 500 and 3,000 meters.
Characterized by its gelatinous physique, this passive organism approximates the dimensions, form, and coloration of a football.
Its body is a deep crimson, adorned with large, cerulean eyes, and possesses a mantle-like membrane extending between its eight appendages.
When confronted with a threat, the squid inverts itself, revealing rows of formidable-looking filaments.
Unlike many cephalopods that undergo a single, terminal reproductive event, the vampire squid exhibits indications of multiple breeding cycles throughout its lifespan.
“Modern coleoids, encompassing squids, octopuses, and cuttlefish, diverged over 300 million years ago into two primary branches: the Decapodiformes, possessing ten arms and including squids and cuttlefish, and the Octopodiformes, with eight arms, comprising octopuses and the vampire squid,” stated Masa-aki Yoshida, a biologist from Shimane University, and his research collaborators.
“Notwithstanding its appellation, the vampire squid features eight arms akin to an octopus, yet it shares critical genomic characteristics with squids and cuttlefish.”
“It occupies a transitional position between these two evolutionary lines, a linkage that its genome elucidates for the first time at the chromosomal level.”
“Although classified within the octopus lineage, it retains elements of a more ancient, squid-like chromosomal arrangement, offering novel insights into the early evolution of cephalopods.”
In a recent investigation, the research team successfully sequenced the genome of the vampire squid using specimens procured from the Western Pacific Ocean.
“With a genome exceeding 11 billion base pairs, the vampire squid’s genetic material is approximately four times the size of the human genome, designating it as the most expansive cephalopod genome ever subjected to analysis,” the authors reported.
“Despite its considerable size, its chromosomes display a remarkably stable and conserved architecture.”
“Consequently, Vampyroteuthis is recognized as a ‘genomic living fossil’—a contemporary representative of an ancient evolutionary branch that preserves fundamental traits from its ancestral past.”
The scientists discovered that it has maintained portions of a decapodiform-like karyotype, whereas modern octopuses have undergone extensive chromosomal fusions and rearrangements during their evolutionary trajectory.
This preserved genomic framework furnishes new evidence regarding the divergence of cephalopod lineages.
“The vampire squid is situated precisely at the nexus connecting octopuses and squids,” remarked Dr. Oleg Simakov, a researcher affiliated with the University of Vienna.
“Its genome unveils profound evolutionary secrets concerning the emergence of two dramatically distinct lineages from a common progenitor.”
Through comparative analysis with other sequenced species, including the pelagic octopus Argonauta hians, the researchers were able to delineate the trajectory of chromosomal alterations across evolutionary epochs.
“The genomic sequences of Argonauta hians (the paper nautilus), a peculiar pelagic octopus whose females have secondarily acquired a shell-like calcified structure, were also presented for the initial time in our investigation,” the researchers stated.
“The analysis indicates that early coleoids possessed a squid-like chromosomal organization, which subsequently underwent fusion and compaction to form the modern octopus genome—a process termed fusion-with-mixing.”
“These immutable rearrangements were likely instrumental in driving significant morphological innovations, such as the specialization of arms and the obsolescence of external shells.”
“Despite its classification as an octopus, the vampire squid retains a genetic legacy that predates both aforementioned lineages,” added Dr. Emese Tóth, a researcher at the University of Vienna.
“It offers us a direct glimpse into the nascent stages of cephalopod evolution.”
“Our study provides the most definitive genetic substantiation to date that the shared ancestor of octopuses and squids bore a greater resemblance to squids than previously hypothesized.”
“It emphasizes that extensive chromosomal reorganization, rather than the generation of novel genes, was the primary catalyst behind the extraordinary diversity observed in contemporary cephalopods.”
The findings were disseminated on November 21, 2025, within the scientific journal iScience.
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Masa-aki Yoshida et al. 2025. Giant genome of the vampire squid reveals the derived state of modern octopod karyotypes. iScience 28 (11): 113832; doi: 10.1016/j.isci.2025.113832
