First, lets get this out of the way: Octopuses, Octopi, or Octopodes? Which is the correct pluralization? Well, you could run a spellchecker, but I found that different ones seem to accept different things. My research seems to indicate that Octopi is incorrect.
The pluralization of words ending in ‘us’ by replacing them with an ‘i’ is a Latin declension, but octopus is a Greek word. So, that leaves us octopuses and octopodes. Both seem to boe correct, but octopuses is the more common term. Your pick.
Now for the interesting stuff! Unlike us red-blooded folk, octopuses have blue blood! This is due to their use of copper based hemocyanin as opposed to the iron based hemoglobin that we use. Oh, and they have three hearts.
For a long time it was thought they couldn’t hear, as they don’t have ears, but newer research shows they can.
They have a relatively short life span, one year for most, up to three for the larger species.
And they have been accused of being very smart. There is an urban legend, I say legend because every story is a second hand account, of the octopus in the aquarium that would sneak out at night to a different tank, eat the fish in that tank, and then go back to his own tank. Some versions report the octopus was eating lobster and others crab. None seem to have been documented.
There has been a documented case of octopuses using coconut shells as a shelter. Not just a temporary shelter, but carrying it with them like hermit crabs.
Although octopuses can change color and shape to camouflage themselves, the amazing mimic octopus has been seen mimicking up to possibly 15 other creatures. (And recently, a fish was discovered mimicking the mimic octopus!)
Now, to really confuse things, some scientists have claimed the octopus actually has six arms and two legs. I wonder what they would have to say about this ‘hexapus‘? It was born with a genetic abnormality and only has six arms. Er…legs. Hmm…two arms and four legs?