Animals Wildlife 9 Outstanding Octopus Facts By Melissa Breyer Melissa Breyer Twitter Editorial Director Hunter College F.I.T., State University of New York Cornell University Melissa Breyer is Treehugger’s editorial director. She is a sustainability expert and author whose work has been published by the New York Times and National Geographic, among others. Learn about our editorial process Updated February 13, 2021 Alexander Rieber/EyeEm / Getty Images Share Twitter Pinterest Email Animals Wildlife Pets Animal Rights Endangered Species The octopus is known for a number of things: its flexible body, ink squirts, and of course, eight arms. With about 300 species, these cephalopods inhabit every ocean of the world and can be found on every coast of the continental United States. You may think you know a lot about these popular creatures, but they have some spectacular qualities that deserve attention. For instance, did you know they can swim four times faster than Michael Phelps? Read on for more facts about the outstanding octopus. 1. They Are Masters of Camouflage Damian Smith/EyeEm / Getty Images Octopuses have impressive camouflaging skills. In the blink of an eye, they can change their color, pattern, shape, and texture to blend in with their surroundings, protecting them from predators and helping them sneak up on prey. This is possible because of thousands of chromatophores — skin cells full of pigment that can change colors. This camouflage is so expertly done that predators can swim right by without noticing the creature at all. The video below shows a mimic octopus, one of the many octopus species that has this chameleon-like ability. 2. Octopuses Have Far-Reaching Brains To go with their eight arms, octopuses have nine brains — one central brain and eight smaller brains, one in each limb. In fact, two-thirds of an octopus' neurons reside in its tentacles. That is to say, an octopus's arms can take on a variety of tasks independently from the central brain. If a tentacle is severed, it will stay active for about an hour. Even more impressive, researchers have found that it will also crawl away on its own, grab hold of food, and direct it to a phantom mouth. 3. They Use Ink To Escape Stuart Westmorland / Getty Images One thing that makes an octopus notable is its famed ink, which is a mix of pigment and mucous and used as a defense mechanism. Upon release, the black cloud obscures an aggressor's view and allows the cephalopod to slip away. Even better, the ink also contains a compound the irritates eyes and dulls an attacker's sense of smell, making it even harder for a predator to continue pursuing the octopus. 4. They Are Fast and Agile Though octopuses are often slow, crawling movers, they have the ability to swim four times faster than Michael Phelps. When they have to attack or make a quick escape, they use jet propulsion to travel at speeds up to 25 miles per hour. They're not just fast — they're also incredibly agile. With no bones and a body made up of 90 percent muscle, octopuses can squeeze their bodies through the slimmest cracks and smallest holes with ease. 5. They’re Millions of Years Old The octopus descends from a creature that lived during the Carboniferous period, 296 million years ago. This creature was the Pohlsepia mazonensis, and we know of it only because of a single, well-preserved fossil. That fossil can now be found displayed at the Field Museum of Natural History in Chicago, Illinois. When looking at the Pohlsepia fossil, you can identify features that would eventually become characteristic of the octopus, including multiple limbs (two short, but eight long) and possibly an ink sac. 6. Octopuses Are Highly Intelligent Aristotle may have thought the octopus was a "stupid creature," but he was mistaken. CUNY biology professor Peter Godfrey-Smith says that octopuses are “probably the closest we’ll get to meeting an intelligent alien.” Researchers say they have developed intelligence, emotions, and even individual personalities. They can solve problems, remember solutions, think strategically, and play — especially with items they can take apart, as shown below. 7. They Have Multiple Hearts To go with their nine brains, octopuses also have more than one heart. In fact, they have three — two to pump blood to their gills and one to circulate blood to the rest of the body, such as the appendages. All three of these hearts are housed in the mantle of the octopus. Interestingly, the heart in charge of circulating blood to the entire body shuts down when the creature is swimming. This is why octopuses are more prone to hiding and crawling than fleeing quickly; the lack of blood flow makes swimming exhausting. 8. They Can Regenerate Lost Limbs A. Martin UW Photography / Getty Images Octopuses are well-known for their ability to regrow lost limbs, and for good reason. While many animal species can regenerate tissue in some capacity, none can do it like the octopus. The cephalopod can restore an appendage in its entirety — including nerves — and the resulting extremity is no weaker than the original. One major player in the regeneration process seems to be the protein acetylcholinesterase (AChE), which aids in cell reproduction and is highly active at certain times of limb regrowth. This protein is present in humans as well, and while there is still much to learn about its role for octopuses, there is hope that it can lead to advances in regenerative medicine. 9. No, the Plural Is Not 'Octopi' If you've been reading and wondering why we're saying "octopuses" instead of "octopi" for the plural of this cephalopod, you would not be the first to be confused. The use of "octopi" was borne of the incorrect notion that the base word has a Latin root, and would thus follow the us > i transition from singular to plural found in Latin-based words like cactus (plural: cacti). However, the word "octopus" comes from the Greek októ (eight) and pous (foot). If you want to follow the Greek exactly, the correct pluralization is technically "octopodes." However, this is more of a piece of trivia. Since "octopus" has very much become an English word, using an English method to pluralize it is best. Hence: octopuses.