The plural of Octopus is Octopuses.by Don Lacey on Sep. 07, 2012, under Education, Environment, Nature, Question of the Day!, Science, That's Life!
Phillip “Space Museum” Olson is the author for today’s blog entry. He is a fellow member of Tucson Atheists Meetup Group, Skeptics of Tucson Meetup Group, FreeThought Arizona and is a panel member of the Desert AIR Podcast.
I recently had a short conversation about Paul the octopus, who received a lot of media attention for apparently predicting the results of the 2010 World Cup. Paul accurately predicted 12 out of 14 games, which has a probability of 0.65%. Not bad, but I’m not really interested in talking about the statistics of the situation. I want to talk about octopuses. I always thought octopuses were pretty cool, but it wasn’t until I started reading more about them that I learned just how freaking weird they are. Finding an octopus who can seemingly predict the outcome of a small number of sporting events is nothing compared to the real weirdness of the octopus.
Octopuses are cephalopods and molluscs. Mollusc is the phylum, which is the same level of classification as Chordata which is where we fall so we really are quite distantly related. Like other molluscs such as clams or oysters, they have no internal or external skeleton but they differ in that they don’t make a shell for themselves and only very seldom will use discard shells or trash as shelter.
There are more than 300 species of octopus, all of which are venomous, which I didn’t realize. I knew that Blue-Ring octopuses were potentially deadly but I did not realize that all the others had venom, too. Outside of the Blue-Ring octopuses, the venom of the others are not considered dangerous to humans though the Blue-Rings venom contains among other things tetrodotoxin which is the same poison found in puffer fish and which is more than 10,000 times as potent as cyanide.
Octopuses in the wild have pretty short life expectancies ranging from six months to perhaps five years. After their mating period they seem to lose interest in feeding and die of starvation. It turns out, though, that if you remove their optic glands, this behavior changes and they eat normally and ultimately have much longer life times.
They have three hearts and pump copper-rich hemocyanin instead of iron-rich hemoglobin. Hemocyanin is less efficient at oxygen transport in warm waters but more efficient in cold water where many octopuses live. Like other cephalopods, octopuses can detect the polarization of light which our eyes cannot. They also have special sensors in the brain that help them detect the alignment of their body to horizontal. They have taste-bud like sensors on their suckers, so they taste whatever they’re touching, but they have a pretty poor proprioceptive sense.
And then there’s the mimicry. Octopuses are pretty much unparalleled when it comes to defensive mimicry. Able to change colors, body shape and size, texture and behavior, octopuses, especially the Mimic octopus, Thaumoctopus mimicus, can have you believing they’re a bit of sea weed, another bit of coral, a flounder skimming the bottom of the ocean, a lion fish or a sea snake. There is no way I’ll be able to describe how incredible these things are, but thankfully YouTube will come to my rescue. Do yourself a favor, and look up YouTube videos of the mimic octopus or the wonderpus octopus.