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By Danna Staaf | September 22nd 2009 11:32 PM | 5 comments | Print | E-mail | Track Comments
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About Danna Staaf

Cephalopods have been rocking my world since I was in grade school. Now I'm a graduate student at Stanford University's Hopkins Marine Station, where I study the development and dispersal of Humboldt... Full Bio

Yup, they found a giant squid. And this is exactly why I get snarlish about people referring to Humboldt squid as giant squid. If you cry "giant!" every time Humboldts appear, then when you get a real Architeuthis, people will think, "What's the big deal about finding one giant squid in the Gulf of Mexico? There are swarms of them off Washington!"
/rant

Anyway, back in July, a standard trawl on a NOAA research cruise hauled in a giant squid--much to everyone's excitement, I'm sure. Curiously, NOAA waited two months before issuing a press release. (I don't really know why, probably there's a perfectly good reason.) Reuters wrote it up right away, and from there it hit the newspapers and blogs.

My favorite
headlines so far:
Holy Architeuthis! Giant Squid Caught Off La*
Federal Scientists Capture, Take Horrible Photo of, Giant Squid!


My favorite unsourced scientific assertion: "The [squid] had been alive but died as it was being brought to the surface because the squid cannot survive such quick changes in water depth."

Generally, squid are not nearly as sensitive as fish or people are to the pressure changes associated with changing water depth. That's because their bodies don't have any gas pockets. Squid are mostly water, and water is virtually incompressible. Of course, humans and fish are mostly water too--with the critical addition of gas-containing sinuses (humans) and swim bladders (fish). It's the air in those pockets that compresses or expands as we go down or up, causing pain and sometimes death.

So, I doubt that pressure change was the immediate cause of the squid's death. But that doesn't mean the article's assertion is completely wrong, because quick changes in water depth are associated with quick changes in temperature, which might be enough to knock out a giant squid. We don't have the laboratory studies to be able to say for sure.

Or, there might be a simple mechanical explanation for its death: being dragged through the water in a net. Certainly this squid is in good condition compared to half-digested remains from whale stomachs, which is what giant squid scientists usually have to work with, but look at how roughed up it is! That is some serious rope burn.



*Louisiana, for anyone who's as slow as I am at recognizing state abbreviations.

Comments

Hank's picture
I had seen stuff on this but I actually did not believe there was a giant squid.  Like dogs named Checkers and Esther Williams swimming pools, I thought it was just some unexplained mystery because you had not written about it.

Thanks for the insight.  Now I know squid don't get the bends so I feel a little smarter.

Danna Staaf's picture
Ooh, interesting! I hadn't even thought about the bends, just straight-up barotrauma--expanding gas inside an enclosed space. That's what makes fish swim bladders pop out of their mouths.

The bends, or decompression sickness, as you probably know, is slightly more complicated. When pressurized, gas moves from airspaces (like lungs) into solution (like blood), and when the pressure decreases, it comes out of solution as tiny bubbles. Tiny bubbles in your bloodstream, of course, cause all kinds of problems.

And fish can get the bends, too! Not too surprising, in retrospect. (Unfortunately the last sentence of this article conflates decompression sickness and barotrauma, but up until that point it's good.)

What about squid? I don't think anyone knows, but I will muse about it more in my reply to Josh's comment below.

That photo really is pretty horrible, though. The squid is so foreshortened you'd never guess it was 20 feet long.

jtwitten's picture
How cool is water?
water is virtually incompressible

Think about it

I wonder if the pressure change could affect gas exchange in the squid?  I know nothing about how squid get oxygen to their cells (which is why I am asking), but pressure/concentration are involved in gas exchange between memebranes and locking oxygen to hemoglobin.  These processes also tend ot be adapted to an organism's environment (e.g., we suck at high altitudes, but llamas do not).

Also, more cephalopod art.  My brother made this:
Vivian the Squid

Danna Staaf's picture
Water is so cool, and that purple octopus is so beautiful. Can I order one? Purple is my favorite color. =)

Great thoughts about gas exchange! I can tell you what I know about ceph circulation, and we can speculate on the rest. Squid have closed circulatory systems just like we do. Their two gills are directly exposed to seawater, and each gill has its own heart, called a branchial heart, which pumps blood from the body into the gills for gas exchange. Once the blood is loaded up with oxygen, it goes to a single larger systemic heart, which distributes it throughout the squid's body.

The respiratory pigment in cephalopod blood is hemocyanin, instead of hemoglobin, which uses copper instead of iron. Copper turns greenish blue when it binds to oxygen, which is why squid have blue blood. Neat! Some people are studying the binding properties of hemocyanin, but there are tons of different kinds (crabs, for example, have it too) and I'm afraid I don't know the literature very well . . .

Do inert gases like nitrogen ever find their way into the squid's bloodstream? If so, would they form bubbles when the squid goes to the surface? Would squid that undergo regular vertical migration have figured out some way around this problem? Is it even a problem at all? Maybe squid like bubbly blood! So many questions!

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