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LiveScience
Though they roam the deep sea around the globe, enigmatic giant squid are all part of the same species, new research finds.
The new study reveals that the genetic diversity of giant squid (Architeuthis) is remarkably low — far lower than that of other marine species examined, said study researcher Tom Gilbert of the University of Copenhagen. The findings suggest that the squid intermingle and mate across the globe.
"The results are extremely surprising," Gilbert told LiveScience.
Monster of the deep
Giant squid are mysterious creatures. They dwell in the deep ocean, making them difficult to observe in their natural habitats. In fact, no one had observed a live giant squid in the wild until 2004. The first video of a live giant squid wasn't released until this year. The animals appear to grow as long as 60 feet (18 meters) and are carnivores that prey on fish and other squid.
Mark Norman
Scientists say giant squid can grow up to about 60 feet (18 meters) long, including their massive tentacles.
Most of what scientists know about the creatures comes from corpses found washed up on beaches or in sperm whale stomachs (the giant squid are apparently a common whale meal). Once in a while, a fishing trawler will entangle a giant squid in its nets. No one had ever published data on giant squid genetics before now.
Gilbert and his colleagues wanted to know if genetics could open any windows into giant squid life, particularly the size and diversity of their populations. No one even knew for sure how many giant squid species might be out there. Estimates ranged from one all the way up to 21, though the highest numbers were unlikely. [Release the Kraken! Giant Squid Photos]
Squid genes
The researchers extracted DNA from 43 soft-tissue samples from giant squid. Some of the samples came from squid found in whale stomachs or washed ashore, whereas others were frozen samples from giant squid dredged up by fishing trawlers. The scientists analyzed mitochondrial DNA, or mDNA, which is found in tiny cell structures called mitochondria. These structures help cells convert energy into a usable form, and their DNA is separate from the DNA in a cell's nucleus; mDNA is inherited from the maternal line.
The mDNA sequences were extremely similar among all samples, the researchers found. The samples exhibited more than 20 times less genetic diversity than other local squid populations, Gilbert said, and there was no population structure. The results suggest that giant squid are all one species. Even more, they're all part of the same big population, meaning there don't seem to be groups of giant squid that interact only with one another. Geography doesn't seem to be a barrier to their breeding, to the extent that any giant squid in the world is a potential partner for any other giant squid in the global oceans.
That's amazing, Gilbert said, given that giant squid vary substantially in body form and live everywhere except at the poles.
"It's very, very hard to explain," he said.
The researchers are now working to confirm the results using nuclear DNA from the giant squid, in order to rule out that possibility that the similarities in mDNA could be some quirk of evolution. If the results hold, they suggest the giant squid may have undergone a recent population expansion and that the young squid larvae disperse over massive distances, traveling randomly across the globe.
"There are huge unexplored questions," Gilbert said.
The researchers report their findings Tuesday in the journal Proceedings of the Royal Society B.
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Leave a Comment:
I bet that thing's hung like a sea horse!
LOL! that's funny
A month or two back, there were the first photos of a giant squid alive in its environment. Now, we're talking about squid mating practices. Rule 34 at work :)
Ha Ha!!! Now thats funny. Thanks for the laugh
I just hate to see anyone get tangled up in the ink of another fishy sex and deceit story. Have a great day.
I'm curious. If mDNA shows that they are all of the same species, is it possible that the Giant Squid is a recent evolutionary species (within last 1-2,000 years)? If so, that could account for the lack of genetic diversity.
A recent population expansion? On what time scale?
Perhaps in the time since whalers killed most of the whales that fed on the squid? Less predators could have led to more squid and an expansion into other areas of the oceans.
The mother of all squid?
Or perhaps they are just not as afraid to leave the extreme depths where whales couldn't get them. Interesting animals, and quite cool.
Doesn't it seem like fewer predators would cause an INCREASE in genetic diversity, though?
My guess is that they went through a genetic "bottleneck" at some point and all of them are descended from a small number of individuals that survived that near-extinction. Same case with some other species such as cheetahs, which are all very similar genetically. If you get enough genetic data you can make a good estimate as to when the bottleneck occurred.
this is what happened to the human race at one point, scientists are saying. Only one population of Humans made it threw that ice age.
No because there are squid fossils.
Actually, Here we are again, that's not completely true.
A recent report shows that there are a small number of males in the world who have a different Y chromosome. It was recently reported and here is the link: http://cosmiclog.nbcnews.com/_news/2013/03/05/17199580-african-americans-y-chromosome-sparks-shift-in-evolutionary-timetable?lite
if this thing thinks that its so tough why doesn’t it come out of hiding in the deep waterways and face me in the octagaan the big lanky wimp? I'll tell you why, because just like the democrats this thing has no balls or motal-center to guide it through life in a respectful and honourable manner. either figure out your own cowardice crap and come to terms with your status as a big girly-man or challenge me down by the docks tonight at eight-thrity right after our cardio session you giant douche.
That was the oddest post I've ever read.
LitterHater,
I suspect that the lack of genetic diversity is due to Obamacare?
Litterhater -- speaking of genetics, did your dad marry his sister? WTH?
I got it! LitterHater is really one of those computer programs that spew random phrases given an initial word or sentence!
What the hell is an octagaan? Perhaps LitterHater has already taken one too many hits in the octogon as it is.
WHO CARES, this is a science info, not for general reading. Isn't there something that would be more worthwhile then squids?
Boring
No one forced you to read it, fool.
Yeah, science has no relation to your life. You'll never encounter a need to use it. It's just a belief system. The computers you used to make that post are driven by God's will and had nothing to do with the application of knowledge from the study of it.
Your comment is bad and you should feel bad!
Clearly you need something a bit more rudimentary if you don't even know the difference between "then" and "than"; so it's not surprising this editorial went way above your remedial head.
I'm surprised that the author didn't mention the possibility of a genetic bottleneck. This term refers to
a situation where the genetic variability within a species is greatly reduced, usually by a very deadly disease
that kills most individuals, leaving only a small number of resistant individuals alive. These geneticly uniform individuals then go on to reproduce and spread over a larger area, perhaps even the entire globe. Thus it
is possible to end up with a globally distributed species with very low genetic variability. One example of a species that has been through a genetic bottleneck in fairly recent times (in evolutionary terms) is the cheetah, which shows very low genetic diversity for a mammalian species across it's entire range.
The "recent population expansion" they refer to implies a population bottleneck, which is what they would be expanding from.
Each form of life is special in some way, which is why we don't want to lose too many species along the way. They all have something to teach us about the amazing properties of life. Keep in mind that we have yet to discover life anywhere else in the cosmos. That should make all forms of life here on Earth very special to us! - RC