Over 95% of all animals on Earth are invertebrates. The octopus is the smartest of them all and has approximately 300 million neurons throughout its body. That’s not much compared to the 100 billion in humans, but it’s a giant leap from the 16 million in frogs.
Octopuses are solitary creatures who spend most of their lives swimming alone, even when it comes time to mate.
Some, but not all, types of male octopus will steer clear from a female mate. Instead of getting close, he’ll send a package of his sperm to her from a distance, which she’ll grab and store for later.
A male will sometimes send a gift along with his package — one of his eight arms, which he severs himself.
Luckily, octopuses can regrow lost limbs, just like starfish. They can even close off the severed artery to reduce blood loss.
When they do bleed, octopuses bleed blue blood, not red. That’s because their blood is high in copper instead of iron.
Octopuses will sometimes deliberately sever an arm to distract a predator long enough to jet away at top speeds of 25 mph.
