“A note on the plural form: Fowler’s Modern English Usage states that ‘the only acceptable plural in English is octopuses’, and that octopi is misconceived and octopodes pedantic. Octopi derives from the mistaken notion that octopus is Latin. It is not. It is (Latinized) Greek, from oktopous, gender masculine, whose plural is oktopodes. If the word were Latin, it would be octopes (’eight-foot’) and the plural octopedes, analogous to centipedes and millipedes, as the plural form of pes (’foot’) is pedes. In modern, informal Greek, it is called khtapodi, gender neuter, with plural form khtapodia.”

So there.

Photo by dive.bc.ca

What is the largest octopus?

“The largest octopus is the North Pacific giant octopus (Octopus dofleini). It lives in the Northeast and the Northwest Pacific Oceans and weighs about 15kg.  Some of the largest ones weigh up to 50kg and measure up to 3-5 meters total length.”

Walktopus? Octopus marginatus

“Two tiny species of tropical octopus have demonstrated a remarkable disappearing trick. They adopt a two-armed ‘walk’ that frees up their remaining six limbs to camouflage them as they slink away from trouble.

‘When we noticed one was walking, I thought my gosh, this is amazing. It’s the first underwater bipedal locomotion I know of,’ says Christine Huffard of the University of California, Berkeley, who captured the behaviour on video.”

Blue-Ringed Octopus Hapalochlaena lunulata

“Hapalochlaena species host in their salivar glands symbiotic bacteria, responsible for the production of the deadly tetrodotoxin (the same toxin produced by puffer fishes). This venom kills through the progressive (reversible) paralysis of all the volunteer muscles. The death is by repiratory paralysis, and can be avoided by artificial breathing. It is worth saying that this species is absolutely not aggressive, and the venomous byte is used only as last option.”