BioEd Online

Japanese researchers have gained an insight into the behaviour of the elusive Taningia danae, one of the world's largest squid species, thanks to the first footage of the deep-sea creature. The video reveals that the animal is a speedy swimmer — not, as was thought, a lazy drifter.

The footage also shows that the squid, which can grow to 2.3 metres long, apparently uses luminescent spots on its arms to confuse prey, and may also use the glowing dots in courtship.

The video was made off Japan's Ogasawara Islands, using an underwater high-definition camera, by Tsunemi Kubodera of the National Science Museum in Tokyo, together with colleagues from the Japan Broadcasting Corporation and the Ogasawara Whale Watching Association. They describe their observations in Proceedings of the Royal Society B¹.

Remains of T. danae often show up in the stomachs of sperm whales. The squid's flabby flesh led experts to think that it floats in the water column like a neutrally buoyant scuba diver. But the new footage shows it can reach speeds of up to 9 kilometres per hour.

When presented with bait, the squid attacked, flashing its luminescent spots, or 'photophores', which contain glowing bacteria. It produced longer glows when faced with the bait rig's lights, suggesting that it was performing some sort of mating dance.