What Every Diver Needs to Know About Octopuses
In diving, there are few things as exciting as an octopus. One minute you're looking at an ordinary patch of coral rubble or a sandy slope, and the next a piece of reef appears to pull itself off, change color, and fluidly pour itself into a nearby crevice.
Whether it’s the giant Giant Pacific Octopus in cold water or the tiny Blue-ringed Octopus in the tropics, encountering one of these eight-armed aliens is always a highlight that gets written in the dive book. But these creatures are far more than just an impressive magic trick.
1. The Ultimate Shape-Shifters
Octopuses are arguably the best camouflage artists on the planet. Their skin is packed with thousands of specialized color-changing cells called chromatophores. They don't just change color; they change texture. By manipulating small muscular bundles in their skin called papillae, an octopus can instantly mimic the spiky texture of algae or the bumpy surface of coral.
Because they completely lack a skeleton (their parrot-like beak is the only hard part of their body), they are incredibly flexible. An octopus can squeeze its entire body through a hole no larger than its eyeballs.
2. Brains and Brawn
Octopuses are widely considered the most intelligent invertebrates in the ocean. They have a central brain, but uniquely, a massive portion of their neurons are located inside their arms. This means each arm can independently touch, taste, and smell its surroundings, practically thinking for itself.
- Tool Users: Some species, like the Indo-Pacific Coconut Octopus, have been observed carrying discarded coconut shells or clamshells across the sandy bottom to use as a mobile armored bunker.
- Wicked Strong: A Giant Pacific Octopus can have up to 240 suckers per arm, and a single sucker can lift up to 35 pounds.
- Blue Blood & Three Hearts: Octopuses have copper-based blue blood, which is pumped by three separate hearts. Two pump blood to the gills, and one pumps it to the rest of the body. Interestingly, the systemic heart stops beating when they swim, which is why they prefer to "walk" along the bottom—swimming literally exhausts them.
3. Octopus Etiquette for Divers
Seeing an octopus in the wild sparks a lot of excitement, but it can also lead to dangerous levels of stress for the animal. Here is how to ensure a safe, respectful encounter:
- Keep Your Distance: You will see much more natural, stress-free behavior if you back off. If the octopus is constantly reacting to you, rapidly flashing colors, or shrinking back into its den, you are too close. If it inks, you've completely stressed it out.
- Watch the Lights: If you are diving at night or using a camera strobe, don't blast the beam straight into their den. Sweep your light past the area and let their sensitive eyes acclimate before taking a photo.
- Never Block the Exit: Always give the octopus a clear path to escape. If they feel cornered, their stress levels skyrocket.
- Look, Don't Touch: Aside from the fact that touching marine life violates basic diving principles, all octopuses possess venom. While most aren't dangerous to humans, the bite of the tiny Blue-ringed Octopus can be fatal in minutes. Plus, many octopuses are covered in a protective mucus layer that our hands can damage.
A Fleeting Life
Perhaps the most tragic fact about octopuses is their incredibly short lifespan. Depending on the species, they generally only live for 1 to 3 years. They are "semelparous," meaning they reproduce once and then die. The males usually pass away shortly after mating, and the females enter a phase called senescence—they stop eating and dedicate the last weeks of their lives exclusively to guarding and aerating their eggs until they hatch.
Because their time on the reef is so short, every encounter is a privilege. Next time you're finning over a rubble patch and see a rock suddenly grow eyes and crawl away, pause, back up, and enjoy the show.
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