Thursday, February 15, 2007
Hunting behavior of Large Bioluminescent Squid (Video)
The scientists' newly developed underwater video camera system took the first live images of the deep-sea large squid, Taningia danae, between 240-940 m deep off Ogasawara Islands, western North Pacific in 2005.
The video footage includes attacking and bioluminescence behaviors and reveals that T. danae is far from the sluggish neutrally buoyant squid previously suspected. They emitted short bright light flashes from their large arm-tip photophores before final assault, which might act as a blinding flash for prey as well as a means of measuring target distance in a dark deep-sea environment. They may also use bioluminescence for attempts at communication.
The paper , which has been published in the journal Proceedings of the Royal Society B is available for free access on the Proceedings of the Royal Society B (Biological Sciences) website.
Source: The Royal Society PR February 14 2007
Video clip 4 'Halogen Light Attacking':
The above video is also available at the BBC News UK story "Large squid lights up for attack":
..Deep-sea squid - once thought to be legendary monsters of the sea - are notoriously difficult to study, and little is known about their ecology and biology. Several species prowl the ocean depths..
 Observations of wild hunting behavior and bioluminescence of a large deep-sea, eight-armed squid, Taningia danae by Tsunemi Kubodera, Yasuhiro Koyama and Kyoichi Mori
Proc. R. Soc. B
Our newly developed underwater high definition video camera system took the first live images of adults of the mesopelagic large squid, Taningia danae, between 240 and 940 m deep off Ogasawara Islands, western North Pacific. The resulting footage includes attacking and bioluminescence behaviours, and reveals that T. danae is far from the sluggish neutrally buoyant deep-sea squid previously suspected. It can actively swim both forward and backward freely by flapping its large muscular triangular fins and changes direction quickly through bending its flexible body. It can attain speeds of 2 - 2.5 m s-1 (7.2 - 9 km h-1) when attacking bait rigs. They emitted short bright light flashes from their large arm-tip photophores before final assault, which might act as a blinding flash for prey as well as a means of measuring target distance in a dark deep-sea environment. They also emitted long and short glows separated by intervals while wandering around the double torch lights attached to the bait rig, suggestive of potential courtship behaviours during mating.
As in the largest squid, Architeuthis, T. danae incorporates numerous tiny vacuoles of ammonia solution within its flesh to enable neutral buoyancy (Clarke et al. 1979). This system makes body musculature flabby and soft to touch in captured animals, leading a number of authors to propose that large ammonical squids are likely to be sluggish and relatively inactive (Hanlon and Messenger 1966; Roper and Boss 1982; Norman 2000; Nixon and Young 2003). Recent observations of live giant squid in the wild (Kubodera and Mori 2005)  revealed that this species is much more active predator than previously suggested. Our in situ observations also show that T. danae is an aggressive and tenacious predator rather than a sluggish, inactive squid.
 First-ever observations of a live giant squid in the wild
By Kubodera T and Mori K.
Proc Biol Sci. 2005 Dec 22;272(1581):2583-6
The giant squid, Architeuthis, is renowned as the largest invertebrate in the world and has featured as an ominous sea monster in novels and movies. Considerable efforts to view this elusive creature in its deep-sea habitat have been singularly unsuccessful. Our digital camera and depth recorder system recently photographed an Architeuthis attacking bait at 900m off Ogasawara Islands in the North Pacific. Here, we show the first wild images of a giant squid in its natural environment. Recovery of a severed tentacle confirmed both identification and scale of the squid (greater than 8m). Architeuthis appears to be a much more active predator than previously suspected, using its elongate feeding tentacles to strike and tangle prey.
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