21 Science Facts You Won't Believe Are True

16. Octopuses Have Three Hearts And Nine Brains

Octopuses are a weird bunch, as they have three hearts, nine brains, and blue blood. Two of the hearts circulate blood to the gills, much like the pulmonary artery carries blood from the right side of the heart to the lungs in humans. The third heart deals with the rest of the body. Eight of its brains control the legs, and one acts as a nerve centre.

Bonus fact: The correct plural of "octopus" is not "octopi", as that is derived from latin, whereas "octopus" is greek. The plural is actually generally accepted to be "octopus" in the case of several of the same species, and "octopuses" when talking about different species.

15. Squid Have Doughnut Shape Brains

Not to be outdone in the bizarre bodies department, the Colossal Squid has a brain shaped like a doughnut. Why does it have a hole in the middle of its brain, you ask? Why, to allow its oesophagus to pass through it, of course.

This whacky plumbing has a major drawback as it means that is a Colossal Squid's eyes are bigger than its belly (which, er, they probably are actually), then it risks brain damage from swallowing anything too big to fit through the hole. This necessitates the squid to rip up its food before eating.