October 8 might be International Octopus Day, but October 31, 2013 is Octopus! day. My book Octopus! The Most Mysterious Creature In the Sea is publishing today.

For the book I was able to travel the world, searching high and low for the most astounding octopus experiences. It was a nine-month whirlwind, spending vacation days on the road (and air and sea), and nights curled up with cephalopod papers, and weekends on the phone with researchers. But I came away with more than enough anecdotes and information to fill an octopedia.

Here are my favorite eight things I discovered about the octopus during my research:

8. The octopus is known to be smart, but most of its neurons are not in its brain. Some two-thirds of an octopus's neuronal connections are distributed in its arms. Talk about distributed intelligence.

7. But that doesn't mean an octopus is dumb. Some species of octopus elude predators by disguising themselves as—and swimming like—other animals, such as fish or sea snakes.

6. The diminutive blue ringed octopus (Hapalochlaena), of James Bond fame, is renowned for being lethally venomous. But I learned that all octopuses are somewhat venomous, which helps them subdue prey. Researchers are also investigating some of these compounds for medical use.

5. The octopus has blue blood. Rather than being an iron-based red blood like ours, the octopus has adapted to life at the low-oxygen depths of the ocean. Its blood is copper based.

4. The octopus can grow back lost arms. Perhaps even more impressive than a lizard regrowing a tail, an octopus can regenerate a full arm, squirmy suckers and all.

3. An octopus will likely only mate once in its short lifetime. Males of many species pass along their genes by severing their specialized third arm and handing it over to the chosen female.

2. The octopus might be well coordinated and quite clever. But one species seems capable of using tools. Watch out, primates.

1. They just might be the most adept camouflage artists on the planet—vanishing in any environment in milliseconds. But researchers have not found any indication that they can see color—with their eyes. So they might be seeing the world, in part, with their skin.

For more, check out my book, Octopus! The Most Mysterious Creature In the Sea--out today!

Illustration courtesy of Ivan Phillipsen