Giant Squid All One Big, Happy Family

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Giant Squid All One Big, Happy Family

Stephanie Pappas, LiveScience Senior Writer
Date: 19 March 2013 Time: 08:01 PM ET
  estimate that giant squid can grow up to about 60 feet (18 meters) long, including their massive tentacles.
CREDIT: Mark Norman  

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.

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 today (March 19) in the journal Proceedings of the Royal Society B.

 

Under the Sea: A Squid Album

LiveScience Staff
Future of Jumbo Squid Questioned
Future of Jumbo Squid QuestionedCredit: courtesy of the Monterey Bay Aquarium Research InstitutionHumboldt Squid (Dosidicus gigas) photographed by Monterey Bay Aquarium Research Institution’s remotely operated vehicle Tiburon at a depth of about 300 meters over Davidson Seamount, off the Central California coast.
Colorful Carpet of Cool Sea Creatures Discovered 2 Miles Deep
Colorful Carpet of Cool Sea Creatures Discovered 2 Miles DeepCredit: David ShaleDigital cameras also captured an image of this juvenile crachiid squid, also called glass squid due to its transparent body.
Longfin Squid
Longfin SquidCredit: Tom Kleindinst / Woods Hole Oceanographic InstitutionIn a study published in 2010 in the The Journal of Experimental Biology, researchers confirmed that longfin squid (Loligo pealeii), which are also a popular seafood meal, can indeed detect sound at low frequencies. Now, the researchers are working to better understand how this hearing mechanism works. [Read full story]
How Whales Attack Squid: Mystery Deepens
How Whales Attack Squid: Mystery DeepensCredit: Roger HanlonA long-finned squid.
Colossal Squid Is No Monster, Study Finds
Colossal Squid Is No Monster, Study FindsCredit: Ministry of Fisheries, New Zealand.The crew of the New Zealand vessel San Aspiring worked to bring aboard the colossal squid they found in the Ross Sea. The squid was barely alive when it reached the surface and observers and crew thought it would be very unlikely to survive if released.
Arrow Squid
Arrow SquidCredit: John A. Anderson | ShutterstockArrow squid like this one have smooth cylindrical bodies and short, pointed tail fins. There are two species of arrow squid, with both looking similar, according to the Deepwater Group Ltd.
Dedicated Mama
Dedicated MamaCredit: CREDIT: Monterey Bay Aquarium Research InstituteIf you think gestating one baby is tough, try 3,000. The squid Gonatus onyxcarries around her brood of 2,000 to 3,000 eggs for up to nine months. The squid moms have their arms full: While carrying their eggs, they’re stuck swimming with their fins and mantle instead of their much more effective arms. 

So why would G. onyx take such care of its thousands of offspring? According to a 2005 study published in the journal Nature, the squid carry their eggs to deep water, where predators are rare. The deep-sea offspring are also larger and more capable of survival than shallow water squid — thanks, mom!

Lone Squid
Lone SquidCredit: ©2007 MBARIA female Octopoteuthis deletron in the water column observed by MBARI’s remotely operated vehicle Ventana on December 6th 2007. The photophores on the arm tips are visible. This animal was observed at 854 meters depth in Monterey Canyon. Spermatangia were present on the dorsal arms. They are visible as white dots.
Vampire Squid
Vampire SquidCredit: 2004 MBARIDespite its terrifying name, the vampire squid is relatively tiny, reaching a maximum of 6 inches (15.4 cm) in length.  It gets its name from its red coloring, glowing, bioluminescent eyes and the cloak-like webbing that connects its eight arms. Although it has similarities with both squid and octopuses, it is actually not a squid but in its own separate family, of which it is the last remaining member; as such, the animal is referred to as a “living fossil.” Its scientific name,Vampyroteuthis infernalis, literally translates to “vampire squid from hell.” Yikes
Klingon Cloaked Squid

Klingon Cloaked SquidCredit: NSFThe Hawaiian bobtail squid and its resident bacterium have a powerful and still somewhat mysterious symbiotic relationship. The luminescent bacteria populate a small pouch on the squid’s underside and pouch on the squid’s underside and provide a sort of “Klingon cloaking device.”

First Videos of Deep-Sea Squid Reveal Aggressive Predator

First Videos of Deep-Sea Squid Reveal Aggressive PredatorCredit: Royal SocietyThe deep-sea eight-armed squid Taningia danae, the world’s largest bioluminescent or light emitting creature, as it swims through the dark seas.

 Loligo Squid

Loligo SquidCredit: Yoko IwataHaving larger sperm may be the result of how the smaller Loligo bleekeri squid fertilize the female’s eggs. (Shown here, the squid species at a spawning ground.)

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