Octopus vulgaris

Presented by Samira Yera

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What if an animal could rewrite its own genetic instructions while it's alive? Octopuses can alter their RNA in real time, helping them adapt to their environment. Scientists discovered that octopuses have thousands more genes than humans, amazing eyesight, and incredible problem-solving skills. This article explains how studying the octopus genome is helping researchers understand why these creatures are often called the "aliens of the ocean."

https://octopus.org.nz/content/dna-proves-octopuses-are-aliens

Evolutionary History

The octopus belongs to the class Cephalopoda, which is a group of marine animals that also includes squid, cuttlefish, and nautiluses. Scientists believe the ancestors of cephalopods first appeared over 500 million years ago during the Cambrian Period.

One of the biggest evolutionary changes in octopuses was the loss of their external shell, which allowed them to become more flexible and move through small spaces. They also developed large brains, advanced nervous systems, excellent eyesight, and strong problem-solving abilities. Another unique adaptation is their ability to edit their own RNA in real time, helping them adjust to changes in their environment.

The octopus belongs to the order Octopoda, which is divided into two main subgroups: Cirrata and Incirrata. Cirrata includes deep-sea octopuses with small internal shells. Incirrata includes the more common shell-less octopuses found in oceans around the world, such as the giant Pacific octopus and the common octopus. These evolutionary adaptations have made octopuses some of the most intelligent and unique invertebrates on Earth.

MAJOR EVOLUTIONARY STEPS TOWARDS OCTOPUS VULGARIS:

Octopuses evolved from ancient mollusks with shells over 500 million years ago. As they gradually lost their shells, natural selection favored traits like flexibility, camouflage, ink defense, and intelligence, helping them survive predators and become some of the most advanced invertebrates in the ocean today.

How Did Octopuses Evolve?

They Lost Their Shells

Ancient octopus ancestors had protective shells. Over millions of years, they lost them and developed soft, flexible bodies that allowed them to squeeze into small spaces and hunt more effectively.

The Challenge of Being Soft-Bodied

Without a shell, octopuses became easy targets for predators. To survive, they evolved camouflage, ink sacs, excellent eyesight, and high intelligence.

They Became Successful Predators

As octopuses evolved, they developed strong hunting abilities and became important predators in ocean ecosystems.

This evolutionary tree shows how different animal groups are related. On the left are mollusks, including snails, clams, chitons, and cephalopods. The red box highlights the coleoids, which include octopuses, squid, and cuttlefish. On the right are vertebrates, such as fish, amphibians, reptiles, birds, and mammals.

The image shows that octopuses are not closely related to vertebrates and share a common ancestor from hundreds of millions of years ago. Even though they evolved separately, octopuses developed high intelligence, strong problem-solving skills, and excellent vision, similar to some birds and mammals. This is called convergent evolution, when different groups evolve similar traits.

Genetics: what makes an octopus unique?

They Can Edit Their Own Genetic Instructions

Unlike most animals, octopuses can change their RNA after it is copied from DNA. This lets them quickly adjust how their bodies work without changing their actual genes.

2. They Adapt Quickly to Temperature Changes

If ocean temperatures change, octopuses can edit thousands of RNA sites within a day. This helps their brains and muscles keep working properly in different environments.

3. Their DNA Evolves More Slowly

Because octopuses rely so much on RNA editing, their DNA stays relatively stable compared to many other animals.

Unlike most animals, which rely primarily on changes in DNA over many generations, octopuses can alter the instructions carried by RNA without changing their DNA sequence.

During this process, enzymes known as ADARs (adenosine deaminases acting on RNA) convert adenosine (A) into inosine (I) within messenger RNA. Because cells interpret inosine as guanosine (G), this modification can change the resulting protein that is produced.

This ability allows octopuses to fine-tune the function of proteins involved in nerve signaling, muscle activity, and brain function. RNA editing is especially common in their nervous system and is thought to contribute to their advanced intelligence and behavioral complexity.

RNA editing also enables octopuses to respond rapidly to changes in their environment. Like the example mentioned above, changes in ocean temperature can trigger the editing of specific RNA molecules, producing proteins better suited to the new conditions. As a result, octopuses can adapt much more quickly than would be possible through DNA mutations alone.

By modifying RNA rather than DNA, octopuses possess a unique form of genetic flexibility that is rare among animals and represents one of the most unusual adaptations in the animal kingdom.

Human Co-Evolution and Impact

Scientists study octopus arms to design soft robots that can be used in medicine, underwater exploration, and rescue missions.
Octopuses have a unique nervous system where each arm can process information on its own. Studying this helps researchers learn more about intelligence, artificial intelligence, and prosthetic limbs.

Octopuses are an important source of food in many cultures around the world.

Today, scientists and conservationists are learning more about octopuses and working to protect their habitats. At the same time, octopuses continue to inspire new discoveries in science and technology, making them valuable to both marine ecosystems and human society.

REFERENCES:

Tseng, A. (2025, February 26). There are 300 types of octopus species, some with internal shells. HowStuffWorks. https://animals.howstuffworks.com/marine-life/types-of-octopus.htm

Welch, C. (2021, September 10). The rise of the cephalopods: An evolutionary origin story. Everything Science. Medium. https://medium.com/everything-science/the-rise-of-the-cephalopods-a-journey-through-500-million-years-of-cephalopod-evolution-ac5c6b36f11e

Island Bay Marine Education Centre. (2015). DNA proves octopuses are "aliens". https://octopus.org.nz/content/dna-proves-octopuses-are-aliens

Grooms, K. (2023, August 4). Octopuses use RNA editing to transiently change their proteins when they get cold. Promega Connections. https://www.promegaconnections.com/octopuses-use-rna-editing-to-transiently-change-their-proteins-when-they-get-cold/

Smith, M. K. (2026, April 1). Curiouser and curiouser: Octopus’s evolution is even stranger than thought. Scientific American. https://www.scientificamerican.com/article/curiouser-and-curiouser-octopuss-evolution-is-even-stranger-than-thought/

Del Dottore, E., Adhami, R., Shahabi, E., et al. (2026). Peripheral control enabled by distributed sensing in an octopus-inspired soft robotic arm for autonomous underwater grasping. Nature Machine Intelligence. https://doi.org/10.1038/s42256-026-01230-y

Timeline structure generated with assistance from Google Gemini (June 2026), an AI large language model developed by Google. URL: https://gemini.google.com/

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