Giant Squids Use Light Flashes to Catch Prey

In September 2005, Tsunemi Kubodera of the National Science Museum in Tokyo and Kyoichi Mori of the Ogasawara Whale Watching Association, achieved the first recording of a live giant squid, Architheuthis, one of the strangest and most elusive marine animals, as the animals live in fact in the deep sea and are rarely seen on the surface.

In December 2006, he even captured on film the moment such a monster was caught while the animal was still alive.

The giant squid was a legend among mariners, who - in many instances before - witnessed the fights led by these monsters with the sperm whales that prey on them; in many occasions the waves washed to the shore dead individuals or just their huge tentacles.

They had given birth to the tales of tentacled monsters able to sink a boat with their arms; moreover, Jules Vernes' "20,000 Leagues Under the Sea," depicts a fight with such a monster.

Now, Japanese researchers, trying to crack the mystery around the biology of these creatures, discovered that the huge deep-sea squid employs blinding light flashes from their armtips to baffle their prey before attacking at speed. The finding was possible due to the newly-developed underwater high-definition video camera, employed by Kubodera's team.

The images depict the mesopelagic (at about 1000 m (3250 feet) depth) large squid, Taningia danae (photo), which grows more than 2.3 meters (7.5 feet) and weighs over 60 kilos (132 pounds), being as large as a young Architeuthis. Taningia proved to be far from sluggish and neutrally buoyant; the large squid could swim nimbly backwards and forwards by flapping its large muscular triangular fins, and turn rapidly due to its flexible body.

The researchers were amazed to see that the squid was emitting bright light flashes, of about one and a half seconds, from large clusters of photophores (light-emitting cells) before starting an attack.

The light "might act as a blinding flash for prey as well as a means of measuring target distance in a dark, deep-sea environment," believe the researchers.

The team captured the images around bait rigs at depths between 240 and 940 meters (780 and 3,055 feet) off the Ogasawara Islands (northwestern Pacific). The attack speeds were up to nine kilometers (5.5 miles) per hour, real bursts of energy if we take on account the pressure and the temperature of water at that depth. "From time to time, the squid emitted long and short glows "suggestive of potential courtship behaviours during mating," adds Kubodera.