Octopus in defensive posture, Mayotte, Indian Ocean

Now you 'sea' me.... World Octopus Day

Something has clearly crossed a line. Off the coast of Mayotte in the Indian Ocean, this octopus has adopted a defensive posture that says: whatever is approaching should reconsider its life choices.

It's a warning octopuses can deliver with style. Instead of armour, they rely on transformation. Together, tiny muscular structures called papillae and pigment-filled chromatophore cells let them change colour, pattern and even skin texture within seconds. The result is an animal that can resemble rocks, coral, algae or shadows. It doesn't simply blend into its surroundings. It becomes them.

And camouflage is only the opening act. Octopuses can vanish in a cloud of ink, squeeze through openings barely larger than their beak, solve puzzles and explore with arms that contain most of their neurons. In a sense, each arm has a mind of its own. World Octopus Day celebrates one of the ocean's great evolutionary oddities: three hearts, eight arms, blue blood. Nature really went off script with this one.