The Octopus has three hearts, but they are all different. One of the hearts is dedicated to pumping blood to the gills, while another pumps oxygenated water from its gills into its blood. The third heart, which is located on top of its head and known as a modified dorsal vessel (or “hearth”), does not pump any blood itself; instead, it acts as an arteriovenous shunt for other parts of the body that needs additional supplies of oxygenated fluid or nutrients like glucose syrup.
Octopuses have impressive camouflage skills.
Octopuses are masters of disguise. They can change color to match the color of their surroundings, texture to match the texture of their surroundings, shape to match the shape of their surroundings, and posture so that they appear less threatening.
Octopuses also have another trick up their sleeves: they can hide in plain sight! This means that when you’re walking along at night with your flashlight beam pointed at them (or worse yet shining directly on them), you might see one or two eyes glowing in your peripheral vision but not necessarily any other body parts until it’s too late for escape.
Some octopus arms are more important than others.
Some octopus arms are more important than others. The forearms, which you can see above, have many sensory and motor functions—they’re used for touch and taste (plus a few other things). There’s an arm at each side of the mouth that can shoot ink when it’s feeling threatened or simply to mark territory. The biggest arm on your average male octopus is its hectocotylus (pronounced hee-toe-cot-uh-plus), which looks like a long club with suckers on it. It’s used for defense; if an enemy tries to grab one of his arms, he may swing this sucker back at them!