The idea of octopuses having “alien DNA” has captured public imagination, stemming from their unique biological features. While extraterrestrial genetic material is not scientifically supported, exploring the origins of this idea and octopus biology reveals a fascinating story of Earth’s evolution.
The Origin of the “Alien DNA” Idea
The concept of octopuses having “alien DNA” originated from a 2015 Nature study that presented the first full sequencing of the Octopus bimaculoides genome. Researchers used evocative language, describing the octopus as “utterly different from all other animals, even other molluscs.” A co-senior author stated, “In this sense, then, our paper describes the first sequenced genome from an alien.”
This metaphorical description highlighted the octopus’s distinct biological complexity, setting it apart from other invertebrates. Media sensationalized this phrasing, leading to a misunderstanding that scientists believed octopuses had extraterrestrial origins. The “alien” label conveyed their extreme evolutionary divergence and unusual traits, not a literal claim about their DNA.
Extraordinary Biology: Unpacking Octopus Uniqueness
Octopuses possess a highly distributed nervous system, with a central brain and significant neuron clusters in each of their eight arms. Two-thirds of their neurons are in their arms, allowing these limbs to act with considerable autonomy, even reacting to stimuli if severed. This decentralized control enables remarkable dexterity and independent action.
Their extensive RNA editing is another unusual trait, allowing them to modify genetic information at the RNA level without altering DNA. This enables rapid protein adaptation, especially in their nervous systems, for quick responses to environmental changes. Octopuses perform RNA editing at tens of thousands of sites, far more than humans or mice.
Octopuses have unparalleled sophisticated camouflage abilities. They instantly change skin color, pattern, and texture by controlling specialized pigment cells (chromatophores, iridophores, and leucophores). This allows them to blend seamlessly or mimic other marine life. Beyond camouflage, octopuses demonstrate complex problem-solving, tool use, and learning capabilities. They can solve puzzles, open jars, and use coconut shells as portable shelters.
Octopuses have three hearts: two pump blood through the gills, and a larger systemic heart circulates blood to the body. Their blood is blue due to hemocyanin, a copper-based protein that transports oxygen efficiently in cold, low-oxygen environments.
Deciphering Octopus Genetics: An Earthly Story
Despite their extraordinary biology, genetic sequencing confirms octopuses are fundamentally Earth-based creatures. Their DNA shows common ancestry with other mollusks and invertebrates. The “alien DNA” notion is a misnomer; their distinctiveness testifies to Earth’s incredible evolutionary diversity.
The large and complex octopus genome is comparable in size to the human genome but contains more genes. This complexity stems from extensive genomic rearrangements and expansions of specific gene families, not whole-genome duplication events seen in vertebrates. For example, octopuses have a massive expansion of protocadherin genes, involved in neuronal development, with 168 such genes—ten times more than other invertebrates. They also show expansions in zinc finger protein families.
Octopus traits result from millions of years of Earth’s evolutionary processes, including adaptive radiation and convergent evolution. Convergent evolution explains how distantly related species independently develop similar features, like the camera-like eyes of octopuses and vertebrates. While their genome is highly rearranged, this genomic plasticity allowed for the evolution of their complex nervous systems and other unique characteristics. Their distinctiveness is a product of terrestrial evolution, adapting to ecological niches with remarkable genetic and biological innovations.