About 300 different species of squid have been swimming in the world's oceans for more than 400 million years [source: National Wildlife Federation]. They caught human interest from the moment one tentacle was seen -- interest that was especially intense when that tentacle was nearly 20 feet (6 meters) long.
Gigantic, powerful squid have been legendary for ages. There are three species that grow to massive proportions: the giant (Architeuthis dux), the colossal (Mesonychoteuthis hamiltoni) and the jumbo, also known as Humboldt (Dosidicus gigas).
While many squid are a few inches long, giant and colossal squid are enormous. The two types are estimated to grow from 35 to 60 feet (10.6 to 18.2 meters) in length -- including body and tentacles. That's larger than a full-length, 40-foot (12.1-meter) school bus. They weigh up to 1,000 pounds (453.5 kg) [source: Smithsonian Institution]. And they have protruding eyes the size of volleyballs. Humboldt squid are the smallest of the three, about 6 to 7 feet (1.8 to 2.1 meters) long and 100 pounds (45.3 kg).
How do these marine animals get so big? The most common explanation is a phenomenon called deep-sea gigantism. The theory suggests that over time, small shallow-water creatures evolved to live at vast deep-sea levels by getting bigger -- likely due to a combination of food supply and the increased size of the predators at great depths. In shallow waters it's advantageous to stay small because there's limited food. But at the extreme depths where massive squid are thought to live, roughly 650 to 2,600 feet (200 to 700 meters) below the surface, bigger creatures have size and endurance on their side when traveling longer distances in search of food. When you're a small fish in a large pond, you're a snack, but if you're the big fish, you have your choice of snacks.
So when you're this massive, is the world your buffet? Could a squid of these proportions even take down a submarine? Let's find out, next.
Giant Squid Attack: Temperament and Reputation
Sea creatures feature prominently in seafarer tales around the world, some dating back to ancient times. In Greek and Roman mythology, there are tales of great battles between man and marine monsters capable of pulling ships underwater. Twelfth century Norwegian sailors told stories of sea creatures they'd seen; by the 18th century, the creatures of Norwegian legend had grown to the likes of islands with arms.
It's thought that giant, colossal and Humboldt squid are aggressive, opportunistic creatures that prey on anything that comes their way -- from easy meals of fish and shrimp to a more sporting hunt of other large cephalopods and whales. The Humboldt, specifically, are known to be fierce, cannibalistic fighters. Mexican fishermen have nicknamed them "diablos rojos," or red devils, because of their bodies' red color and their hostile nature.
In other modern accounts, a squid of "colossal dimensions" figured in Jules Verne's 1869 novel, "Twenty Thousand Leagues Under the Sea," said to be a fictionalized account of a real encounter between a French navy ship and a giant squid. Whether the original account is entirely fictional or not, the novel peaked the public's interest in deep-sea gigantism and marine attacks, and certainly isn't the only account of squid attacking ships.
In the 1930s, the Royal Norwegian navy's 15,000-ton tanker, the Brunswick, was attacked three separate times by giant squid. Each account tells of a squid pursuing the tanker and striking it suddenly, tentacles wrapped around the hull [source: The Museum of Unnatural Mystery]. Fortunately for the sailors -- yet unfortunately for the squid -- the steel of the ship proved either too slick or too hard (or maybe both) for the tentacles to grapple and pierce the prey. Each squid that tried to land the Brunswick ended up perishing after sliding into the tanker's propellers.
As recently as 2003, a giant squid attempted to take down a boat -- this time a French yacht sailing, ironically, in the Jules Verne Trophy, a prize for the fastest global circumnavigation by a yacht. The 26-foot-long (7.9-meter) squid gave up before its demise, or that of the boat.
Some scientists are skeptical that squid are dangerous to humans or watercraft, suggesting that they're a species with a fish-based diet, and therefore have no need to attack humans or the steel of a ship.
Whether they're indeed pursuing our vessels or not, none of the predatory, gigantic squid has yet to take down a ship, yacht or submarine, but it hasn't been for lack of trying.
For more information about squid and other creatures of the sea, visit our resources on the following page.
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More Great Links
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