Happy World Octopus Day: The Smartest Thing You'll Meet Underwater

Rick Harkins   Oct 08, 2026

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Today is World Octopus Day, and it's well deserved. Octopuses might be the most impressive animal you can run into on a dive.

They're smarter than you'd think

An octopus has around 500 million neurons, about the same as a dog. The strange part is where they are. About two thirds are in the arms, not the head. That means the arms can do a lot of the thinking on their own.

They use tools

In 2009, scientists in Indonesia watched veined octopuses collect discarded coconut shells and carry them around to use as shelter later. That's planning ahead. Among animals without a backbone, octopuses are one of the very few known tool users.

Three hearts and blue blood

Yes, really. Three hearts, blue blood, and a brain shaped like a doughnut.

Where can you see one?

Octopuses live in oceans all over the world, and warm reefs like the Caribbean and Indonesia are great places to look. They're hard to spot, though. Check crevices, small holes, and the edges of rocks. A neat pile of shells outside a hole is a good clue someone's home.

Move slowly, keep your distance, and never touch. If one decides to show itself, you'll know you were calm enough to earn it.

We have two trips coming up where you can go looking: the Bahamas Aqua Cat Liveaboard (October 31 to November 7) and Raja Ampat in Indonesia (February 8 to 18, 2027).

Not certified yet?

You don't need to finish everything at home. Our Referral Diver course covers classroom and pool training here in Harrisburg. Then you finish your open water dives on vacation, at any SSI dive center. Your rating is good for six months.

The next class is November 14 and 15 at Derry Township Pool, $400.

Source: Natural History Museum, "Octopuses keep surprising us"