1. They have three hearts! Two of an octopus's hearts work solely to pump blood to its gills, while the third main heart pumps blood through the rest of its entire body.

2. Their blood is bright blue. Unlike humans who have red, iron-based blood, octopuses have blue blood! Their blood uses a copper-based protein called hemocyanin, which is super efficient at carrying oxygen through freezing, low-oxygen ocean waters.

3. Two-thirds of their brain lives in their arms. Octopuses have around 500 million neurons, but most of them aren't in their head! Each arm has its own mini-brain network, allowing an arm to taste, touch, and move independently even if it's exploring a tricky rock crevice.

4. They can squeeze through a hole the size of a coin. Because octopuses are invertebrates with no bones or hard internal shells, their body is soft like jelly. As long as their hard parrot-like beak can fit through an opening, their whole body can squish right through behind it!

5. They are expert escape artists and puzzle solvers. Octopuses are incredibly smart marine animals. In aquariums, they have been caught opening childproof jar lids from the inside, solving complex mazes, turning off lights by squirting water at light switches, and escaping through drainage pipes!

6. They shoot a blinding cloud of ink to make a getaway. When threatened, an octopus sprays a dark cloud of ink into the water. This ink obscures the predator's sight and contains chemicals that dull the predator's sense of smell, giving the octopus time to jet away safely.

7. The correct plural is "octopuses." While many people guess "octopi," the word comes from ancient Greek rather than Latin! Language experts and marine biologists agree that octopuses is the most accurate plural form.