Here we have an octopus, casually eating its breakfast. Then a man with a camera interrupts the meal, managing to piss the tentacled creature off so bad it puffs itself up like a giant balloon.
This is apparently what octopi do when messed with by human interlopers. The guy wielding the camera was alarmed as the purple beast grew frustrated... and hangry. He wrote in the video’s caption:
“This octopus was NOT impressed when I interrupted its morning feeding stroll during my scuba dive on 31 Jan, 2017 in Melbourne, Australia. It blew itself up like a parachute multiple times to try to intimidate me, before trying to torpedo me like a bowling ball! Octopuses are beautiful, intelligent creatures and this one was using its most creative methods of self defence [sic].”
Octopi have a variety of self-defense methods, such as dispelling ink and camouflaging themselves to blend in with different environments. They can also self-amputate their own limbs to escape the clutches of a predator, much like a lizard does with its tail.
They also, um, get swole. Which is probably the fiercest of all their defense mechanisms.