Pitch black. She moved slowly but was sure of herself, felt no fear.  She hadn’t felt fear since she was very young, when she lived in the light and everything chased her. But now she was bigger, smarter, everything ran away. Now she feared nothing; nothing except the sharp teeth. But she could hear them coming, their rapid clicking easy to pick up. Except that one time… The time she lost one of her tentacles. She pulled back quickly when she heard the noise — loud and very close  — but it was too late. She remembers the pain, the anger, the shock of being attacked. She was not used to being attacked so the encounter was….disturbing. She had not forgotten, never would. But then she saw something far off, the pulsing blue light. Something to eat? She swam quickly through the dark, cold depths. As she approached the light she reached out with her tentacles to probe her prey…

July, 2012. off Chichijima, Japan.

…The scientists watched, heavy with anticipation. Would this finally be the time for someone, the first humans, to see the giant squid in its natural habitat? See the ancient Kraken of legend in its home? After years, decades of searching, after 100 missions and 400 hours, they sat there staring at the pulsing blue light 3000 ft below them. Waiting. Hoping the light would signal food for the squid, as it should. Then there it was: a single arm reaching up from the depths, probing the light. They screamed with excitement and watched as she pulled back, not sure what it was. Then she tried again and again. Finally, on the fifth try she decided to attack and made a frontal assault, tried to grabbed the prey near the light with everything she had. At that moment she had come out of the ancient legends and unto the light. The search for the giant squid was over.

First View of the Giant Squid: from Edith Widder’s TED talk on: How We Found the Giant Squid.

And so concluded endless years of speculation on the truth of the Kraken: the old Norse legend of a “sea monster” as big as a ship. A legend that developed over centuries — indeed millennia — driven by part ignorance, part fear but also by likely sightings of giant squid. Stories of a horrendous sea creature that attacked ships and sailors across the globe.Your worst nightmare and part of the world’s historical ocean lore.

Legend of the Kraken, a giant sea creature that attacked ships. Many of those legends may have been based on observations of giant squid.

The idea of the Kraken appears in Melville’s Moby Dick in 1851; played a major role in Jules Verne’s Twenty Thousand Leagues Under the Sea in 1870; and appeared as the Watcher in the Water in Tolkien’s The Fellowship of the Ring, lurking in a lake beneath the western walls of Moria. The truth is that the giant squid (Architeuthis dux), which may have been the basis for most of these myths and legends, has a real-life story almost as mysterious as unicorns and dragons. Because even though we know the intimate details of the surfaces of the Moon, and even Pluto, somehow a giant animal in the deep-sea still remains unknown in modern times, like the dinosaurs of old. And although specimens have washed ashore and been observed at sea for thousands of years it wasn’t until 2012, over 2,000 years after Aristotle described the teuthos  the giant squid — in his Naturalis historia, that a live giant squid was observed in its natural habitat at almost 3,000 ft (900m) depths (Ellis 1998).


In terms of sheer size, squid take the prize among invertebrates, which is not entirely unexpected from a lineage that has been around for some 480 million years. Giant squid existed in the past as they do today, including the Paleozoic shelled nautiloid Cameroceras which reached a size of 30 ft (9 m); the Mesozoic vampire squid Tusoteuthis (to 35 ft [11 m]), and the Mesozoic coleoid Yezoteuthis at 18 ft (5m). All of these come close but are smaller than the giant squid of today.


Ancient giant squid (from left): Cameroceras, Tusoteuthis and the Yezoteuthis .

But just how big do giant squid get? The truth is we really don’t know. Most of what we know is from beaks found inside their principal predators, sperm whales, and from sucker marks on sperm whale bodies. But here is what we do know: as of 2011 there were a total of 677 specimens washed up on beaches or caught in fisherman nets going back to 1545 (Guerre et al., 2011). As with most large animals, especially at sea, there have been many misrepresentations and exaggerations of their size.

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Giant squid beak found in sperm whale stomach.

Although giant squid up to 65 ft. have been reported it is generally agreed that the maximum size of the giant squid is 43 ft (13 m) for females and 33 ft (10 m) for males, as measured from the end of the mantle to the tip of the two long tentacles (O’Shea and Bolstad, 2008). That’s plenty big enough for me and I can’t imagine what it would be like to come face-to-face with one in the dark ocean depths! However, “largest” is open to debate and many will point that squid size should be based on both body size and total length. Using that criteria the colossal squid (Mesonychoteuthis hamiltoni) with a maximum size of 12–14 m (39–46 ft) long, is the largest squid in the sea, and even more so when you compare the length of the mantle (main body) which is around 13 ft. among colossal compared to 7 ft. for giant squid (see below). But either way you measure it they are both giants of the sea.


A comparison of giant squid (left) with medium- and large-sized colossal squid. Photo:

And interestingly giant squid are found all over the world, with as many as 21 different species proposed for this widely distributed species. However, recent genetic research has shown that all populations are a single species, one big happy global family so to speak, all Architeuthis dux (Winkelmann et al., 2016). This is likely due to their highly mobile larval stage, the tiny paralarvae, which occurs in shallow water and is dispersed by global currents. From there giant squids mature extremely rapidly and reach mature size in 2-3 years. As they get bigger they move deeper and primarily prey upon other smaller squid and disperse even further (Bolstad and O’Shea, 2004).

Paralarvae of giant squid. They are generally smaller than 0.25″ in length.

In fact one of the few things currently bigger than giant squid are their predators, which are primarily sperm whales (Physeter macrocephalus). Indeed, the expedition that first found the giant squid in its natural habitat used sperm whale distributions to find them, which was near steep, submarine canyon-rich continental slopes near Chichijima Island, Japan at 1300-3200 ft (400-100 m) depths (Kubodera and Mori, 2005). During that first epic appearance in 2004, which was recorded by a remote still camera (not video), a giant squid got her tentacle snagged on a jig and fought for over 4 hours, and over a 1000 ft. range in depth, to detach it. This was both the first direct evidence that giant squid were active predators and not the sit-and-wait stalkers that many believed, and also a testament to the squid’s intelligence, patience and determination. Eventually, however, the tentacle broke and the piece was brought to the surface and measured at 18 ft. (5.5 m). They are truly remarkable creatures.

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Figure from Kubodera and Mori (2005) with photographs of a snagged giant squid and tentacle and the depths of the encounter.

But like many unique things on this planet giant squid are at risk due to our activities, particularly climate change and associated pH shifts which are affecting the world’s ocean. As the ocean becomes more acidic the statocysts in the giant squids brain, which are used for navigation, may be impacted and cause disorientation on top of additional changes which include ocean warming and changes in cold deep-water current patterns. As a result giant squids are more likely to end up on the warm surface where they become moribund and are found by fisherman or wash to shore. According to Guerra et al. (2011), because cephalopods are complex organisms with an active lifestyle their low oxygen-carrying blood proteins will make them highly vulnerable to the effects of global warming and ocean acidification. Thus they unwillingly serve as an indicator of future warming of the world’s oceans, particularly for the submarine canyon environments in which they are found. Indeed, giant squid stranding records indicate that most squids wash up on beaches during periods of warm ocean bottom temperatures. Other human threats include damaging acoustic waves from seismic surveys, pollutants (metals, PCBs and/or organochlorine pesticides), and deep-sea fisheries (Guerre et al., 2011).

Given its place in our history, in our myths and legends, and after all the effort to find the giant squid in its natural habitat, imagine the irony of a species just recently seen for the first time disappearing from the earth due to human activities. There is a lot I could  say about this situation but I’ll leave you with these final comments from Edith Widder, one of the co-discovers of the live giant squid habitat, that said it best:

How could something that big live in our ocean and yet remain unfilmed until now? We’ve only explored about five percent of our ocean. There are great discoveries yet to be made down there, fantastic creatures representing millions of years of evolution and possibly bioactive compounds that could benefit us in ways that we can’t even yet imagine. Yet we have spent only a tiny fraction of the money on ocean exploration that we’ve spent on space exploration. We need a NASA-like organization for ocean exploration, because we need to be exploring and protecting our life support systems here on Earth.

Exploration is the engine that drives innovation. Innovation drives economic growth. So let’s all go exploring, but let’s do it in a way that doesn’t scare the animals away, or, as Mike deGruy once said, “If you want to get away from it all and see something you’ve never seen, or have an excellent chance of seeing something that no one’s ever seen, get in a sub. He should have been with us for this adventure. We miss him”


  • Bolstad, K. S. and S. O’Shea. 2004. Gut contents of a giant squid Architeuthis dux (Cephalopoda: Oegopsida) from New Zealand waters, New Zealand Journal of Zoology, 31:1, 15-21, DOI: 10.1080/03014223.2004.9518354
    Ellis R. 1998 The search for the giant squid. Guilford,CT: The Lyons Press.
  • Guerra, Á.; González, Á.F.; Pascual, S.; Dawe, E.G. (2011). The giant squid Architeuthis: an emblematic invertebrate that can represent concern for the conservation of marine biodiversity. Biological Conservation 144 (7): 1989–1997.
  • Kubodera T, and Mori K. 2005 First-ever observations of a live giant squid in the wild. Proc. R. Soc. B 272, 2583–2586. (doi:10.1098/rspb.2005.3158)
  • O’Shea, S. and K. Bolstad. 2008. Giant Squid and Colossal Squid Fact Sheet. Accessed May 15, 2016.
  • Widder, Edith, 2013. How We Found the Giant Squid. TED Talk. 8:31
  • Winkelmann, I. et al. 2016. Mitochondrial genome diversity and population structure of the giant squid Architeuthis: genetics sheds new light on one of the most enigmatic marine species. Proc. Royal Soc. B. DOI: 10.1098/rspb.2013.0273

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