Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
Was having a discussion about optic nerves yesterday, and I thought of you. Why? Because I mentioned how the idiotic placement of the human optic nerve is one demonstration of the stupidity of the human race’s so-called Intelligent Designer, and my cow-orker mentioned that octopuses don’t have this problem, and therefore have much less flawed eyesight. I figure you know all this far better than I do, but I thought you’d like to know you’re water-cooler conversation all around the world…
my cow-orker mentioned that octopuses don’t have this problem
Yeah, but what about the cows that he orks?
I can see why they call it giant. It is nice to see the diver in comparison.
While you’re in Seattle, make sure you are at the aquaruim in time for the feeding of these magnificent beasties (and the wolf eel!). Unfortunately, they don’t just throw a small child in, like some of us would like, but it’s fun to watch nonetheless.
That is a very naughty octopus…he’s showing his beak to the camera!
Speaking of feeding aquarium confined cephalopods: where I grew up in southern New Zealand the university has a marine research lab with a small public aquarium display attached. In a big corner tank they had a common octopus of the sort that lived in the harbour. We went to visit one day the grad student who was on ‘duty’ told us they had come in that morning to find that all the crabs that they kept in a tank on the other side of the room from the octopus were gone. There was a trail of water from the octopus tank across the concrete floor and up the side of the crab tank. Turned out the lid of the octopus tank had not been properly secured.
To link this to another post this tells you both that octopus have good eyesight and that they are able to plan. It also tells you that either this octopus noticed its tank wasn’t secured or it spent every evening testing the lid… Oh and it also knew where home was, ahh.
I have also used the point about wanting eyes like cephalopods to the creationist inclined. Its worse than just having the wiring run at the front, the whole retina is back to front in vertebrates. First to get struck by light are the blood vessels that supply the retina, you can see these as shadows if someone shines a small torch into your eye from an angle. Then comes the ganglion cells that do the initial processing and only then do you get to the photoreceptors, except they face the back, we have to have a reflective layer to bounce those pesky photons into the right place. It is clearly a cludge, some useful mutation was fixed in a lineage that had things inverted and it was more useful than the inversion was a problem and it became one of those things where the jump in morphospace to a cephalopod retina gets wider and wider as time goes on.
Dang it! You’re coming to Seattle? Where are you going to be? When? How did I miss this? Gah!
While on your trip did you come upon any Pacific Northwest Tree Octopi?
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We’re making the planet a better place for cephalopods. It also helps that humans are busily…
Trapped in a cunning prison!
Oh, no, what are you doing now?