快猫短视频

DECKED out in a crisp new lab coat bought specially for the occasion, squid expert Steve O鈥橲hea bends over a slimy mass of tentacles. The unidentified specimen on the table in front of him is about a metre long, with arms as thick as sausages, bristling with suckers and curved hooks. On the door of the small lab at the Institute for Antarctic and Southern Ocean Studies in Hobart, Tasmania, hangs a tattered notice: 鈥淪quid Dissections in Progress鈥�. Inside, the tension mounts as we await O鈥橲hea鈥檚 diagnosis.

This mystery squid was hauled out of the sea near Macquarie Island, about halfway between Tasmania and Antarctica. An examination of its ovaries and beak tells O鈥橲hea it is a juvenile and would have grown to an immense size. 鈥淚t could be a new species,鈥� he tells a television crew from New Zealand. If he is right, the specimen will open a new chapter in the quest to understand the elusive gargantuan squid that prowl the ocean depths.

Once the stuff of maritime myth, these animals are now firmly part of mainstream science. Thanks to a flurry of recent discoveries we now know a lot more about one particular type 鈥� the giant squid, or Architeuthis. And there are big surprises. For one thing, it seems that the giant squid is less ferocious kraken and more puny ocean drifter 鈥� albeit with an other-worldly and somewhat macabre sex life. What鈥檚 more it鈥檚 not even the biggest squid on the block; there is another species down there that seems more likely to fit the stereotype of a vicious sea monster. And there are tantalising signs that yet more, unknown, species of gigantic squid are lurking in the deep. But the giant squid may be heading for extinction, and so researchers are scrambling to film one in the wild before it鈥檚 too late.

Giant squid have haunted the human imagination for centuries. The writhing arms of the 鈥済iant octopus鈥� are a common theme in whalers鈥� tales (see 鈥淢ythical Beasts鈥�), and kraken-like creatures crop up again and again in seafaring lore. About 400 years ago, reliable written records started to appear describing tentacled sea monsters washed up on beaches. In 1856 a Danish researcher, Japetus Steenstrup, named the specimens Architeuthis, meaning 鈥渃hief squid鈥�. Many of his contemporaries, though, doubted any squid could grow so big.

Doubts about the animal鈥檚 identity lingered on for the next 130 years. In the absence of fresh specimens, scientists had to rely on rotting corpses washed up on beaches, or the stomach contents of the sperm whales that prey on them. Not surprisingly, these pulpy fragments were not very revealing.

But now, at last, we are getting some answers. Over the past decade, dwindling fish stocks have forced commercial trawlers to venture ever further and cast their nets ever deeper. This means they have strayed into giant squid territory and are now catching large numbers of pristine specimens every year. In total, more than 300 Architeuthis carcasses have been found, and O鈥橲hea has examined about 105 of them, more than any other researcher in the world.

We now know that Architeuthis can grow up to 13 metres long, the females larger than the males. It has huge eyes, up to 30 centimetres across, to peer through the near-total dark of the cold deep sea, searching for the flashes of bioluminescence that betray its prey 鈥� small fish and squid. Alongside its eight standard arms the giant squid has a pair of enormous bungee-like tentacles studded with toothed suckers for trapping its struggling victims while its parrot-like beak shreds them.

One surprising conclusion is that Architeuthis does not deserve its fearsome reputation. Far from being powerfully built and ferociously armed, it has a relatively weak body and long, weedy tentacles. In fact it鈥檚 a wonder that Architeuthis manages to eat at all. 鈥淭hey鈥檙e using what are a bit like those pruning shears on very long poles used to trim trees and they鈥檙e managing to grab big, aggressive prey,鈥� says Mark Norman, another squid expert at the Melbourne Museum in Australia. 鈥淗ow do you manage those very long chopsticks? I鈥檇 love to see them feeding.鈥�

Lack of muscle power is not the only thing to convince scientists that Architeuthis is a big softy. Unlike shallow-water squid, its body is packed with ammonium ions. These give it a horrific carpet-cleaner-like smell when dissected, but they are there for a reason 鈥� to alter the density of the squid鈥檚 tissues and so give it neutral buoyancy. If it functions like other ammoniacal squid that have been observed in the oceans, Architeuthis simply hangs in the water, drifting, rather than darting, in search of prey.

About 5 years ago a commercial fisherman showed O鈥橲hea sonar imagery of a weird shape, barely moving, suspended at a 45-degree angle, about 10 metres above a school of hoki. 鈥淚nstead of leaving the net down to catch fish, out of curiosity, he hauled it immediately, and he found a near-pristine Architeuthis in an otherwise empty net,鈥� O鈥橲hea says.

While our picture of the giant squid is beginning to mellow, its sex life is no bedtime story. In 1997, Norman and his colleague Chung-Cheng Lu, now at the Graduate Institute of Zoology, National Taiwan University, published the results of their investigations of the first mated female recorded (Nature, vol 389, p 683). They found sperm packages or 鈥渟permatophores鈥� embedded in the skin of the female鈥檚 arms. Females store the sperm here until they are ready to use it. Giant squid, unlike some of their relatives, do not have a specialised arm for transferring sperm to the female. Instead, they have a penis to do the job. As the pair wrote: 鈥淚t seems that male giant squids may use their muscular elongated penis to 鈥榠nject鈥� sperm packages under pressure directly into the arms of females.鈥�

Those penises can grow up to one and a half metres long and are rather unwieldy. O鈥橲hea has found males implanted with their own spermatophores. 鈥淚f we are talking about a 200-kilogram squid, this is an animal with a 20-gram brain. It鈥檚 not very bright and it is trying to coordinate a metre-long penis,鈥� says O鈥橲hea. 鈥淗e鈥檚 going to get a bit confused.鈥�

It seems that females might also get muddled during sex, which can be bad news for the male. In a paper submitted to the New Zealand Journal of Zoology, O鈥橲hea and Bolstad describe finding numerous fragments of a 鈥渃lub鈥� from the end of an Architeuthis tentacle in the stomach of a female. This is the first report of cannibalism but O鈥橲hea thinks it probably wasn鈥檛 intentional 鈥� he suspects the tentacle of a male swept too close to the female鈥檚 beak during mating and she ate it.

What happens after the male injects the spermatophores is still guesswork. But if Architeuthis does as other squid do, the female probably mixes eggs from her ovary with jelly secreted from glands inside her body or 鈥渕antle鈥�. When she contracts her mantle, the egg mass is extruded through an opening called the funnel to be cradled in her arms in the form of a small gelatinous sphere. Chemicals in the egg-jelly matrix activate the spermatophores buried in her arms, and the spermatophores migrate towards the surface of the skin, where they explode, shooting sperm out onto the egg mass. The sperm then burrow into the mass to fertilise many thousands of eggs. O鈥橲hea thinks this egg mass drifts for a week or two before the larvae hatch.

But where do these monsters get together? While Architeuthis have washed ashore or been caught in fishing nets the world over 鈥� from New Zealand to Aberdeen 鈥� they seem to prefer breeding in the nutrient-rich waters at the point where two ocean currents converge. In the northern hemisphere, these frontal regions occur off Greenland and Norway in particular. In the south, they are found off South America, South Africa, Tasmania and New Zealand, where there have been more Architeuthis caught recently than anywhere else in the world.

No one knows how many giant squid are out there, or even how many different populations there might be. But based on catch data, O鈥橲hea thinks there are two separate geographical groups that migrate to New Zealand waters to breed. One gathers off the west coast of South Island in July and August, the other off the east coast in very late December, January and February.

It was on a trip to one of these areas in February 2001 that O鈥橲hea鈥檚 team, funded by the Discovery Channel, made a momentous catch. They trapped some tiny squid larvae swimming 250 kilometres east of New Zealand above a small submerged bank. These turned out to be Architeuthis larvae 鈥� the first ever caught 鈥� and raised the exciting hope of witnessing a giant squid growing in captivity.

Sadly, the jubilation lasted barely longer than the champagne. Over the next 3 days, all the larvae died. Since then, O鈥橲hea and his assistant Kat Bolstad, who is researching methods of growing squid in the lab as part of her PhD, have learned a great deal about how to keep larvae alive. 鈥淚n retrospect,鈥� he says, 鈥渆verything we did was wrong.鈥� O鈥橲hea thinks the lighting, the prey they gave the larvae to eat and even the shape and material of the tanks were inappropriate.

Before they try again with giant squid larvae, O鈥橲hea and Bolstad want to perfect the technique with other deep-ocean species. They plan to try with larvae of the warty squid, Moroteuthis ingens, another deep-ocean dweller that is smaller and more accessible than Architeuthis. If the project succeeds, it should also help answer another major unresolved question about deep-water squid, including Architeuthis: how long they live.

Given that an adult female can grow up to 13 metres and weigh some 275 kilograms, you might think that it would take many years to reach full size. But George Jackson, a squid researcher at the University of Tasmania, reckons it could take less than 2 years, making the giant squid one of the fastest-growing animals on the planet.

He bases his estimates on the growth of the squid鈥檚 鈥渟tatoliths鈥� 鈥� tiny bits of bone that act as balance organs. A specialist in squid that live in warmer waters, Jackson has published a series of papers estimating age based on the number of 鈥渞ings鈥� in the structure of the statoliths. He has demonstrated that, in tropical species at least, these rings are laid down daily. The same seems to happen in similar organs called otoliths in many species of fish, including those that live in cold water. And if this holds for the cold-water Architeuthis, it means their lifespan is less than 2 years. 鈥淭here is no way of verifying at the moment that rings are laid down daily in Architeuthis, but it seems to be a reasonable assumption.鈥� Jackson says.

Mark Norman is cautious. 鈥淚n cold-water species, it could just as easily be that a ring gets laid down after each major meal,鈥� he says 鈥� although nobody knows how often giant squid eat. Whatever the answer, O鈥橲hea and Bolstad hope to know within a few months. By introducing a chemical tracer into the water in which a warty squid is growing, and later examining the statoliths, they will be able to work out how frequently rings are laid down. What goes for the warty squid will probably hold for Architeuthis, they think.

Another major question about Architeuthis is how many species exist. At least 20 have been described since the genus was established, some from only a beak or a piece of tentacle. In February, at the Cephalopod International Advisory Conference in Phuket, Thailand, Tsunemi Kubodera of the National Science Museum of Japan in Tokyo presented work on specimens from Japanese waters. Because some of the male specimens have slightly different morphologies, such as shorter arms, he thinks there could be two separate species living off Japan.

From giant to colossal

But the evidence is contradictory. And different preservation techniques can create confusing morphologies. For instance, the mantles of squid that have been frozen and defrosted appear flatter than those preserved fresh. O鈥橲hea hopes to end the debate with a new paper, co-authored with researchers at the National Institute of Water and Atmospheric Research in Wellington, New Zealand, and the University of Delaware, submitted to the Journal of the Marine Biological Association of the United Kingdom. The team analysed gene sequences from the mitochondria of 18 Architeuthis specimens from the north and central Atlantic and south Pacific. They found no significant differences between the giant squid specimens, but marked differences between the giant squid and one other squid species. This supports the idea that there is only one species: Architeuthis dux.

But Architeuthis is not the only large squid out there. In 1925, another kind, Mesonychoteuthis hamiltoni, was described, based on two tentacles found in the stomach of a sperm whale. It took until 1985 before a complete specimen, a juvenile just over a metre in length, was trawled up from the depths. We now know that Mesonychoteuthis hamiltoni is a true monster of the deep. O鈥橲hea drew on its awesome nature to invent its common name: the colossal squid.

In April, O鈥橲hea made headlines around the world when he took delivery of the corpse of an immature colossal squid, caught trying to pilfer the catch of a trawler in the Ross Sea off Antarctica (快猫短视频, 12 April, p 18). Its mantle length of 2.5 metres was the longest of any squid ever reliably recorded. Architeuthis adults can grow up to 13 metres long, but most of this is made up of the two long tentacles: there are no unequivocal records of any Architeuthis with a mantle longer than 2.25 metres. Based on this specimen and what is known about squid growth rates in general, researchers think that colossal squid adults may grow to be 15 metres long, with a mantle measuring up to 4 metres.

The colossal squid is fascinating 鈥� and fearsome. In many ways, it is the mean machine Architeuthis was always thought to be. Unlike Architeuthis, it has a powerful, muscular fin, and grows rotating hooks all along its arms. When it comes to a fight, chances are that Mesonychoteuthis would give any sperm whale a run for its money. Although a whale is still the likeliest winner in any contest, the scars and gashes found criss-crossing whales鈥� faces bear witness to the ferocity of these deep-sea punch-ups. The colossal squid鈥檚 physiology suggests it is a fast-moving hunter, and, since the ocean temperature in the Antarctic is similar at all depths, it can hunt near the surface with ease. Architeuthis is also adapted for cold water but lives in seas nearer the equator. In these waters, warmer temperatures near the surface force the giant squid to stay in the cold depths.

The colossal squid is not necessarily the end of the story. Unidentified large beaks that have been found in the stomachs of sperm whales are tantalising clues to the existence of other, unknown gigantic squid.

It is even possible there are specimens waiting to be recognised as new species. For example, when the Ross Sea specimen came up, it reminded Jackson of a similar, smaller version kept in a tub of formalin at the Tasmanian Museum. He invited O鈥橲hea to examine it, and this is the body O鈥橲hea is puzzling over in the Hobart dissecting room. 鈥淚鈥檝e never seen anything like it,鈥� he tells the TV crew. Jackson maintains that this specimen is a young colossal squid, but O鈥橲hea isn鈥檛 sure. It was caught much further north than any Mesonychoteuthis hamiltoni has ever been caught before. And the proportions are different. The colossal squid鈥檚 mantle was fat, but the one in the Tasmanian Museum is skinny. The differing maturities of the specimens could explain the differences, or it could indeed be a new kind of large squid. Only more extensive tests will tell.

Perhaps the most pressing issue is what will become of the creatures in the future. O鈥橲hea worries that the very trawlers that enable us to study giant squid could also be driving them to extinction by destroying their eggs and taking their food. 鈥淕iant squid could be on their way out,鈥� he says.

Architeuthis may be endangered, but the signs are that smaller, shallow-water squid are flourishing. Squid are very sensitive to changes in the environment and convert food into growth very efficiently. What鈥檚 more, they are highly responsive to temperature changes. An increase of just 1 掳C during the juvenile phase will double a squid鈥檚 weight. This means that global warming is probably good news for shallow-water and tropical species. So too is the crashing of ocean fish stocks around the globe. 鈥淲ith global warming and this removal of predators, shallow-water environments in particular are very conducive for the expansion of squid populations,鈥� Jackson says.

But where does this leave the deep-ocean, cold-water Architeuthis? The answer is not clear. 鈥淚 do agree that frequent trawling in their habitat is likely to capture the adults and destroy egg masses, if indeed they are laid in the same area,鈥� says Lu. 鈥淏ut past records of stranded Architeuthis in Newfoundland, for example, show long periods of no sightings. I would want to see evidence before I would say Architeuthis is endangered.鈥�

For all the recent discoveries, many mysteries remain. Clyde Roper, a giant squid expert at the Smithsonian National Museum of Natural History in Washington DC, is often quoted as saying that we probably know more about the dinosaurs than about the giant squid. One reason for our ignorance is that no one has ever glimpsed a live adult giant squid in the wild. The holy grail of researchers like O鈥橲hea is to film one in its natural habitat, about 600 metres down in the dark, deep ocean. In 2004, he will make his first attempt, and to help him he has a secret weapon in his freezer 鈥� giant squid pheromones.

The trip is scheduled for July, when he plans to squirt extracts of male and female giant squid gonads from a remotely operated submersible. 鈥淭hese things come into New Zealand waters to breed. They鈥檙e sex-crazed. If you have a pheromone being released, you鈥檙e not just going to get a fleeting glimpse,鈥� he argues. While giant squid are not known to rely heavily on a sense of smell, unlike sharks, for example, it鈥檚 worth a try, Norman says.

Other groups, such as a Smithsonian-led team, funded by the National Geographic Channel, are also trying to film a giant squid, but O鈥橲hea insists that being first is not his priority. 鈥淭o me, it鈥檚 more about doing this to the best of my abilities,鈥� he says. 鈥淓ach new day when I download my barrage of email, I look for that one message that someone else has finally filmed the animal alive, and 鈥榚lated鈥� would be my response.鈥�