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May 7, 2010

Friday Squid Blogging: The Colossal Squid isn't a Vicious Predator

New research shows that, even though it's 15 meters long, it's not the kraken of myth:

Its large size and predatory nature fuelled the ancient myth of the underwater "kraken" seamonster and modern speculation that the colossal squid must be aggressive and fast, attributes that allow it to prey on fish and even give sperm whales a hard time.
Yet as the creature is seldom encountered let alone studied, there are no direct measurements of the colossal squid's behaviour.

So instead, the team used a set of routine metabolic rates for other deep-sea squid species and extrapolated the data to match the colossal squid's size.

[...]

"Our findings demonstrate that the colossal squid has a daily energy consumption 300-fold to 600-fold lower than those of other similar-sized top predators of the Southern Ocean, such as baleen and toothed whales," says Dr Rosa.

[...]

This study reveals a single 5kg Antarctic toothfish would provide enough nourishment for a 500kg colossal squid to survive for 200 days.

[...]

"The colossal squid is not a voracious predator capable of high-speed predator-prey interactions," says Dr Rosa.

"It is rather, an ambush or sit-and-float predator that uses the hooks on its arms and tentacles to ensnare prey that unwittingly approach."

Posted on May 7, 2010 at 4:26 PM • 17 Comments

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Comments

From reading the excerpts:

1) It *is* a predator
2) It isn't a voracious predator
3) Is it a "vicious" predator? (I suppose that depends on how "vicious" is defined...)

Posted by: semantics at May 7, 2010 5:29 PM

Now that's settled who wants to swim with a Mesonychoteuthis hamiltoni, aka Not-the-Kraken? I hope not to have nightmares about the obscene teeth-hooks-claws on its tentacles where the suckers are supposed to be.

Posted by: mcb at May 7, 2010 6:03 PM

We're supposed to believe that a half-ton animal needs something like an ounce of prey a day to function? Either the reporter effed something up, or the scientists made some order-of-magnitude error in their calculations somewhere.

Posted by: RobertB at May 7, 2010 9:43 PM

@RobertB: or there's more things in heaven and on earth than are dreamt of in your philosophy. ;) It sounds unlikely, but stranger things have happened.

Posted by: Muffin at May 8, 2010 5:14 AM

From the description of its hunting method I got that it is a "hooker" ...

Posted by: Gweihir at May 8, 2010 10:13 AM

Yes, but what's the best way to cook one?

Posted by: Tom M at May 8, 2010 2:53 PM

@Robert, squid are cold blooded. How much of a whales' energy requirement goes into maintaining body temperature? Squid are not air breathers; whales are. How much energy is consumed by hourly returns to the surface? Squid are ambush predators; whales either graze (baleen whales) or pursue (sperm whales, etc), requiring continual motion.

Posted by: FreeWilly at May 8, 2010 5:46 PM

But haven't CS's been videoed attacking deliberately laid trap-pots? That's not 'ambush' behavior, and it struggled long and hard enough with the trap to loose a tentacle - which I'd say was pretty hard fighting....

Posted by: Dom De Vitto at May 8, 2010 5:56 PM

People hardly ever encounter these things, which for an active, aggressive predator would mean extreme rarity, but it's a low-energy-use ambush predator, so there can be comparatively many of them hovering about in the deep water, and if no one drags nets through there, we wouldn't find them.

So having lots of these 'colossal' sized hook-tentacled ambush predators hovering about in the deep water waiting to ambush anything that comes near it is meant to make them seem *less* monstrous?

Posted by: pfogg at May 8, 2010 8:51 PM

@RobertB: an alligator can go months between feedings during the winter. I understand they only wake up when they start to rot -- that's how low their metabolism goes.

Don't use your intuition -- outside of the cases your familiar with, it's useless.

Posted by: kangaroo at May 8, 2010 9:28 PM

@Tom M:
Probably by the time they have become "giant" they are no longer so good to eat. Better to harvest them when younger.

In general there are two ways to cook squid. They can either be cut into bite-sized pieces and stir-fried. With this method, they must be very lightly cooked - less than a minute, but at high temperature as normal for stir-fry, or they become tough and rubbery (tough and rubbery is the normal state in most restaurants). The other way is to stew them for a long time; after initially becoming tough, the squid meat gradually becomes tender, as for many meats which consist mainly of muscle tissue.

Posted by: Gourmet at May 9, 2010 3:13 PM

So the researchers took data from other squid (no data from this one) and projected it along some kind of size curve/linearly to say how much food the largest possible squid needs. Dangers of extrapolation ?

Posted by: RobS at May 9, 2010 9:45 PM

Tell that to Jack Sparrow...

Posted by: AC2 at May 9, 2010 11:52 PM

@Tom M: They aren't good to cook. I think someone in Galicia found one and try to sell it. One with a fish shop bought it, try to cook and found that it was not good.
I don't have the source of this information, I listen to an interview few months ago.

Posted by: caca at May 11, 2010 6:38 AM

I don't know how dangerous this squid is, but I have been subjected to some sensational TV on one of the "science" channels (Discovery SCI, NationalGeo, HistoryInternational, TLC, etc) describing how the Humboldt squid now populating the Sea of Cortez is happy to come eat you if you get too close. I have no idea how closely the hyperbole of the "experts" matches reality.

Posted by: jbl at May 11, 2010 5:08 PM

Good documentary on SciTrek on cable on the Humboldt Squid off the Sea of Cortez, this week.
They will attack people, during feeding frenzies,
and as a part of some squid social architecture,
but not otherwise, apparently.

Lots of toothy suckers.

They also have to eat more than their bodyweight daily to meet their growth needs.

The red coloration disappears them in the sea water there.
Other neat stuff.

Posted by: Peter E Retep at May 11, 2010 7:55 PM

Squid "jigging" brings elusive cephalopods up from Sea of Cortez

http://www.scientificamerican.com/blog/post.cfm?...

Posted by: footerest at May 12, 2010 10:58 AM

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