Tuesday, September 3, 2013

When you think of squids, you normally think about swift, powerful beasts with suckers and hooks that can crush you in seconds. Grimalditeuthis bonplandi defies this stereotype. This deep-sea squid is a sluggish swimmer with a fragile, gelatinous body. Its tentacles are not the muscular, sucker-covered appendages that you might expect to see. Rather, they are long, thin and simply too weak to get prey. Furthermore, the squid lacks suckers, hooks and photophores on its tentacles. This makes it seem like a sad excuse for a squid. But not so, according to a recent paper, published by researchers from the Monterey Bay Aquarium Research Institute (MBARI).

Generally, squids have eight arms and two tentacles. The tips of the tentacles, known as clubs, are broader and are armed with suckers or hooks. These tentacles are used to capture prey. G. bonplandi, however uses a different strategy altogether. Much like how an angler fish uses bioluminescence to lure prey, it is hypothesized that G. bonplandi uses small fluttering motions of its tentacle clubs to lure its prey.

Instead of suckers and hooks, G. bonplandi possesses fin-like membranes on the clubs of their tentacles. When the membranes flap, the clubs seem to be swimming on their own. The tentacles themselves do not move by themselves. When G. bonplandi wants to extend its tentacles, it does not use the muscles in its tentacles to do so. Instead, its clubs swim away from the body, with the tentacles trailing behind them. When it wants to retract its tentacles, the squid will swim down towards its clubs, wind up the tentacles, clubs and all, and hide them within its arms.

The researchers think that this behaviour causes small shrimp and squid (which they found remnants of in the squid’s stomach) to be attracted to the fluttering motion, which emulates the movement of small swimming animals. Even though they would be invisible in the darkness of the deep-sea, the researchers postulate that the vibrations can disturb glowing micro-organisms in the water, making them visible. Alternatively, the movements might be similar to the movements used by the prey to attract mate. The movements might even mimic the movements of even smaller animals that G. bonplandi’s prey eat (A case of the predator pretending to be the prey!).

The research was done by doing close examination of videos of G. bonplandi, collected by MBARI and several oil-industry Remotely Operated Vehicles (ROVs). Prior to this, only dead or dying specimens of G. bonplandi had been seen. The usage of ROVs allows the scientists to observe these creatures in their natural habitat. In addition to ROVs, the researchers also carried out several dissections on preserved squid to study their anatomy.

Read all about it: http://bit.ly/15TxR17
Image URL: http://bit.ly/1fwEJ5Y
Video: http://bit.ly/18oHPpY

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