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Video: Deep-Sea Squid Goes Fishing in the Dark

The two wimpy tentacles dangling from the squid species Grimalditeuthis bonplandi have long baffled marine biologists. How can the creature use these long, unusually nonmuscular projections—which also lack hooks or suckers—to capture prey? The first videos of the squid in its deep-sea environment strongly suggest that the answer is simple: It doesn’t. Instead, researchers contend, it uses them to lure prey within range of its other eight arms, which are shorter and much more muscular. In seven videos made by remotely operated vehicles (one off the California coast, six near oil platforms in the Gulf of Mexico), the researchers observed G. bonplandi wriggling the fleshy clubs on the ends of its tentacles in a way that resembles the undulations of a small, swimming animal (see video). Even though no footage shows the squid actually catching a meal, the squirming tentacle tips could attract prey in several ways, the researchers suggest today in the Proceedings of the Royal Society B. Motions of the clubbed tips could stimulate bioluminescence in microorganisms or small creatures swimming nearby, which could in turn entice larger prey suitable for the squid. (An analysis of museum-preserved specimens hints that G. bonplandi eats small crustaceans and juvenile squid, possibly even those of its own species.) Or, the wrigglings could create pressure vibrations that directly invite prey to draw near. Finally, small swirls shed from the tentacle tips as they trail through the water could serve as a trail of bread crumbs that leads a potential victim—merrily searching for a meal of its own—to its doom. Any one of these techniques, or a combination, could work; many other deep-sea creatures are known to use similar tricks. But until cameras actually catch the squid catching a meal, the researchers caution, the ideas they’ve put forth are just speculation.