What Aristotle Got Wrong About the Magnificent Octopus

Octopuses have a few characteristics that make them stand out as one of the most intelligent mollusks in the ocean. These slippery, strange ocean creatures, characterized by their large craniums and big eyes, belong to thousands of species found across the globe.

Octopuses inhabit environments ranging from coral reefs to the inky depths of the ocean, making them masters of adaptability. Not only are many of these species intelligent, but some of them can even shapeshift, completely altering their appearance to blend into their background. Additionally, octopuses have incredible vision and can detect polarized light, which helps them camouflage. Overall, these fascinating creatures contribute greatly to the diversity of ocean life, so why not discover the top ten facts about these cephalopods? Below, we present ten facts that might just rewire the way you think about these eight-armed creatures.

1. One Deep-Sea Octopus Skipped Eating for 4.5 Years

Imagine dedicating more than four years of your life to protecting your unborn young. Day in and day out, guarding your eggs, with not a bite of food in sight. Well, scientists off the coast of California witnessed this in a deep-sea octopus, Graneledone boreopacifica.

For 53 straight months, this octopus mom clung to a ledge guarding her eggs from predators, debris, and other potential dangers. That is the longest-known brooding period of any animal on Earth. This ultimate act of devotion, known as semelparity, is common in octopuses, which reproduce once in their lifetime and then usually die. Semelparity is a harsh, sacrificial process that is triggered by their bodies, ensuring their offspring get the most protection before venturing out on their own. Ultimately, this act helps to ensure each generation gets a head start.

2. Aristotle Thought Octopuses Were Dumb – Boy was he wrong

In the History of Animals, one of the most notable texts in biology, Aristotle called octopuses “stupid creatures”. He believed that since octopuses would swim toward a human hand when lowered in the water, they were unintelligent creatures of the ocean.

What he misunderstood to be stupidity was actually curiosity. Recent scientific studies have confirmed that octopuses are highly intelligent creatures. Octopuses are capable of long-term memory, problem-solving, and even observational learning. Moreover, they can play, explore, and interact with their environment in ways that Aristotle could not have dreamed of.

3. Octopus Can Learn By Watching

Octopuses not only explore; they also remember. One particular study showed that octopuses could retain visual memory from a task for at least five days after training. To us, five days might not seem long, but for a creature with no bones and a vastly different brain structure than ours, it is groundbreaking.

Octopuses possess both short- and long-term memory, which is part of what makes their curiosity so meaningful. This is not just instinct; it’s observation, recollection, and then acting accordingly. This means that with all the quirky tricks an octopus might try, it can remember whether they worked or failed. In other words, it can learn. Observational memory and problem-solving abilities make them some of the most complex animals in the ocean. Check out this video of a sneaky octopus securing its snack with ease.

4. They Bleed Blue

Unlike us, octopuses have blue blood. The reasoning behind this blue blood is the copper-based molecule, hemocyanin. This molecule enables efficient oxygen support in cold, low-oxygen environments. This adaptation is vital for octopuses that live in deep, icy, low-oxygen waters. It is important to mention, however, that hemocyanin is not as efficient in warmer waters, which makes octopuses particularly sensitive to temperature change.

5. They Have Three Hearts (And One Takes a Break)

Octopuses have three hearts. Two of their hearts pump blood to the gills, and the third pumps it to the rest of the body. Remarkably, the main heart stops beating when they swim. Because of this, swimming can be a costly process for octopuses, which is why octopuses tend to crawl along the ocean floor.

6. Their Arms Have Minds of Their Own (Sort of)

Each of an octopus’s arms (sort of) has its very own mind. Neurons, which are specialized cells that carry information throughout the body, are mostly found in the brain, spinal cord, and nerves in humans. Octopuses, on the other hand, are just built differently. In an octopus, about two-thirds of its neurons are located in its arms rather than its central brain. This means that every octopus arm can explore, touch, taste, and even manipulate objects semi-independently. In experiments, researchers have seen severed octopus arms continue to respond to stimuli. That is because the arms contain neurons capable of decision-making, without the brain to intervene.

7. Masters of Mimicry And Disguise

These cephalopods are pretty advanced shapeshifters. Using specialized skin cells, called chromatophores, octopuses can instantly change the geography of their skin to match their surroundings. These specialized cells expand or contract to show combinations of pigment to match their environment.

These masters of trickery go even further in species like the mimic octopus (Thaumoctopus mimicus), changing their body shape and behavior to impersonate other animals, including lionfish, sea snakes, and flatfish. Survival tactics like these give octopuses an evolutionary advantage in the ever-changing ocean environment.

8. Octopuses are venomous

Surprise! These eight-limbed cephalopods are venomous creatures. The venom is produced in their salivary glands and injected through their beak to immobilize prey like crabs, shrimp, and fish. While most octopuses are not harmful to humans, one particular species stands out as a deadly serious threat: the blue-ringed octopus. Small but deadly, it is one of the most toxic cephalopods.

Blue-ringed octopuses belong to the genus Hapalochlaena. These small, brightly colored species carry a deadly toxin in their venom called tetrodotoxin. Tetrodotoxin is a neurotoxin that can cause paralysis, then death within minutes. According to sources, this toxin is about 1200 times more toxic to humans than cyanide. Currently, there is no known antivenom. And the injection? Painless. Most victims do not know they have been bitten until it is too late. The good news is that blue-ringed octopuses are rarely encountered and are generally apprehensive around humans.

9. Born with a Built-In Survival Kit

Many octopus hatchlings have Kölliker’s organs. These are temporary, umbrella-like bristles that bloom across their bodies right before hatching. One specific example observed that these organs increased the hatchling surface area by 35–87% in some species.

It is thought that for a small, newly hatched octopus, staying afloat is important; therefore, increased buoyancy helps them remain suspended in the water column. In addition, these organs help hatchlings escape from their eggs by acting as an anchor. Although useful, these structures do not last long; usually, within 48 hours of hatching, these organs begin to break down and disappear completely.

10. Escape Artists

Octopuses are legendary escape artists. Their reputation for escaping from captivity is so strong that scientists decided to research this hardwired behavior. In 2004, researchers completed a multispecies study that revealed over a dozen octopus species are practically born to break out of their enclosures, leading them to design specialized enclosures. The most famous of the escapees was Inky, who not only escaped through a gap in the lid but also made his way across the floor, down a drainpipe, and back to the ocean. Inky’s breakout highlights the intelligence of this species. Check out Inky’s story here.

Creative Creatures of the Sea

Octopuses are brainy, blue-blooded, shape-shifting, fascinating creatures of the sea. With their knack for outsmarting expectations, these are just a few of the many facts that showcase how incredible these cephalopods are. Whether they are solving puzzles, changing shape, or sacrificing themselves for their offspring, they constantly remind us of the resilience that lies at the heart of evolution.

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