We know very little about giant squid, because they live at great depths and have never been studied alive. They're truly mysterious, and were long thought to exist only in 'tall stories' from sailors who'd had a drink too many. These tales told of huge creatures with massive arms attacking small sailing ships, but with no hard evidence scientists couldn't be sure if such animals really existed.

In the past hundred years, biologists have been able to glean some information only because occasional giants are washed up, stranded on beaches or are accidentally caught in nets trawling the bottom of the sea for deepwater fish (See the box 'How's this for size?'.)

This giant squid of the architeuthis genus was caught off the west coast of Tasmania.
A live specimen would be about eight metres long, including two very long clasping tentacles.
Photo by David Paul

The biggest recorded giant squid are 18 metres long, but it is possible that larger ones exist. We know that sperm whales - giants themselves at up to 20 metres in length - like to eat these enormous squid but that they don't do so without a struggle (see the box 'Submarine warfare'). Huge scars from squid suckers are sometimes found on sperm whale skin. In the past, the sizes of giant squid were estimated from the size of these sucker marks, but we now know this isn't very accurate because scars can grow; a sperm whale could have been scarred while young and then grown larger.

How's this for size? In 1997, one of the largest giant squids ever found in Australian waters was accidentally caught - alive! - by a fishing boat off Devonport in northern Tasmania. The boat's crew phoned CSIRO Marine Labs and arranged to bring the monster in for study and dissection. (CSIRO has one of the few labs in the country that's large enough to dissect a giant squid in!) It was, of course, simply impossible to keep the creature alive. This has never been achieved. The squid was transported to CSIRO in Hobart, where cephalopod experts from around the country gathered to examine it, measure it, photograph and dissect it. They discovered that it was a female, carrying a sperm package that had been inserted by a male. (For more on the sex life of squids, see the box 'A riveting sex life'.) This was the first time in the world that a female giant squid with a sperm package in place had ever been found. The international scientific community was quickly alerted. Dr Lu, from the Museum of Victoria, prepares a female giant squid for dissection at CSIRO's Marine Labs in Hobart.

Much of the length of a giant squid is taken up by the two long feeding tentacles, which can be 10 metres or more long. They have spoon-like enlargements, called clubs, at their ends. This is where the biggest suckers - golf-ball size and with sharp-toothed rims - are found. The eight arms are about two or three metres long and about 50 cm around at the base. They are covered with suckers. The mantle (the main body) can be up to 2.5 metres long.