Planet Earth

Goblin Shark Gives a Lesson in Dismantling Your Face to Eat

InkfishBy Elizabeth PrestonAug 17, 2016 2:02 PM

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The goblin shark is a weird deep-sea creature first discovered off the coast of Japan in 1898. It has a ghoulish appearance, thanks to jaws that can stretch well away from the rest of its head. Scientists have assumed the goblin shark uses this trick to eat—but until recently, no one had actually watched one catching prey in the wild. In 2008 and 2011, divers working with the Japanese television broadcaster NHK managed to capture two goblin sharks (Mitsukurina owstoni). Before rereleasing the animals, they made five video recordings of the sharks striking and eating—in one case, a shark was taking a swipe at a diver's arm. Now Kazuhiro Nakaya, of Japan’s Hokkaido University, and others have analyzed that footage frame-by-frame to try to understand how a goblin shark does its thing. As expected, the sharks put their stretchy (or "protrusible") jaws to work when attacking. The researchers broke the process down into steps:

  1. Swim with your mouth hanging open a little.

  2. Suddenly stretch your jaw open to about 110 degrees. (Don't try this at home if you have traditional primate jaws.)

  3. Shoot your top and bottom jawbones forward at the same time.

  4. Chomp down.

  5. Gradually retract your jaws, taking another chomp as you do so.

https://www.youtube.com/watch?v=9q3BD7gjncQ There are other sharks in the ocean that can jut their jaws forward to eat, but none of them comes close to matching the talent of the goblin shark. The researchers dubbed the goblin shark's behavior "slingshot feeding." The animal's jawbones, they discovered, travel forward at a startling 3.1 meters per second. At the jaw's maximum reach, it stretches as much as 9.4 percent of the shark's whole body length. That's 2 to 10 times farther than any other shark's jaws can move. If Olympic swimmer Katie Ledecky stuck out her jawbones that far while she was in the pool, her teeth would be nearly 7 inches in front of her face. The scientists think goblin sharks may have evolved this way to make up for slow swimming speed. If you can't overtake your prey with your whole body, why not just send your jaws ahead of you? And with little food available in the deep sea, predators need to seize every meal opportunity they can get their mouths on. Image: NHK

Nakaya, K., Tomita, T., Suda, K., Sato, K., Ogimoto, K., Chappell, A., Sato, T., Takano, K., & Yuki, Y. (2016). Slingshot feeding of the goblin shark Mitsukurina owstoni (Pisces: Lamniformes: Mitsukurinidae) Scientific Reports, 6 DOI: 10.1038/srep27786

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