10 Surprising Octopus Facts

Octopuses are some of the weirdest and most fascinating creatures in the ocean. With eight arms, multiple hearts, and brains distributed throughout their bodies, they often feel more like aliens than regular sea animals. Here are ten facts that still surprise most people.

1. They have three hearts and blue blood. Two hearts pump blood through their gills while the third serves the rest of the body. The main heart actually stops beating when they swim, which is why they prefer crawling or short jet bursts. The blood is blue because it carries oxygen on copper instead of iron, and that chemistry is why the octopus needs all three hearts.

2. They have nine brains in total. One central brain and a smaller “brain” in each arm. This allows each arm to taste, touch, and even make simple decisions somewhat independently. The tasting is literal. Suckers carry chemotactile receptors, a family of sensors found only in cephalopods, that pick up chemicals on whatever they touch, so an arm probing a crevice can tell prey from rock by contact.

3. They can change both color and texture instantly. Using special cells and tiny muscles, octopuses can alter their skin to match rocks, coral, or seaweed in milliseconds. It’s one of the most advanced camouflage systems in nature.

4. They can squeeze through tiny spaces. With no bones, an octopus can flatten its body and slip through any opening larger than its beak, the only hard part of its body. Aquarium staff have plenty of escape stories.

5. They are highly intelligent problem solvers. Octopuses have been observed using tools, opening jars, solving mazes, and even playing with objects in captivity. Some have figured out how to squirt water at lights to turn them off.

6. Their ink does more than create a smokescreen. When threatened, they release a cloud of ink. Some species’ ink also contains compounds that can temporarily dull a predator’s sense of smell or taste, giving them extra time to escape. That is a serious advantage against something like a shark, which pairs an acute sense of smell with the ability to detect a heartbeat through open water.

7. They live fast and die after reproducing. Most octopuses only live one to two years. After mating, females lay eggs and then stop eating so they can guard them until they hatch. Once the babies emerge, the mother’s life is usually over.

8. Lost arms can keep moving and grow back. If an octopus loses an arm, it can regenerate it. Even more surprisingly, the detached arm can continue moving and reacting on its own for a while because it has its own mini nervous system.

9. Some species can walk on two arms. The coconut octopus has been filmed strolling across the seafloor on just two of its arms while carrying shells or holding others up. It looks like a strange little underwater alien out for a walk. Their deep-water cousins are stranger still, among them the dumbo octopus, which hovers over the seafloor on ear-like fins nearly 7,000 meters down.

10. The blue-ringed octopus is tiny but deadly. Only about the size of a golf ball, this species carries enough venom to be dangerous to humans. Its bright blue rings serve as a warning to stay away.

The three hearts and the nine brains are still the two that get me every time. Which one surprised you most? Drop it in the comments below.

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