[新聞] Shark Swallows Another Shark Whole

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Munching on Bamboo (Shark)
A shark has been caught on camera making a meal of another shark along Australia's Great Barrier Reef. Released earlier this month, the pictures show a tasseled wobbegong halfway through swallowing a brownbanded bamboo shark.

Daniela Ceccarelli and David Williamson, from Australian Research Council's Centre of Excellence for Coral Reef Studies, chanced on the spectacle while conducting a fish census on the fringing reef off Great Keppel Island.

"The  first thing that caught my eye was the almost translucent white of the  bamboo shark," Ceccarelli said in an email. Expecting to find the front  part of the bamboo shark hidden under a coral ledge, Ceccarelli swam  closer—and the highly camouflaged wobbegong materialized.
"It  became clear that the head of the bamboo shark was hidden in its  mouth," she said. "The bamboo shark was motionless and definitely dead."


Previous analyses of the shark species' stomach contents had shown that wobbegongs do eat other sharks.


"I  doubt that this is the first time such a thing has been seen," said  Ceccarelli, who added that she does think this is the first published  photograph of a wobbegong swallowing another shark.



Even Match
The wobbegong sits with the dead bamboo shark in its mouth along Australia's Great Barrier Reef.
Both  species of predator and prey involved in this rarely witnessed episode  grow to similar sizes—approximately 39 to 59 inches (100 to 125  centimeters) from head to tail. The two sharks also share much of their  ranges in the western Pacific, where they hang out on the seabed around  coral reefs.

"In  areas where wobbegongs are common, their paths are [indeed] likely to  cross," Ceccarelli said. "Bamboo sharks forage along the bottom, often  poking their heads in holes and under ledges and overhangs to feed  primarily on [bottom dwelling] invertebrates."

According to the online fish encyclopedia Fishbase, brownbanded bamboo sharks are also often spotted in tide pools and can survive for 12 hours out of water.



Carpet Shark
With their flat bodies and fringed faces, it's probably no surprise that tasseled wobbegongs—like this one in waters off Indonesia—are also known as carpet sharks.

"They  lie on the seabed, camouflaged against the bottom, waiting motionlessly  for potential prey to swim past and then attack at lightning speed,"  Ceccarelli said.

As  opportunistic ambush predators, wobbegongs are "unlikely to be picky  about what they prey on," she added. That helps explain why the  Australian wobbegong was able to make a meal of a shark almost as big as  itself.


As  with many sharks, the wobbegong's jaws dislocate, helping them to  engulf large prey, and their teeth point backward so they can keep a  grip on their meals.
"With enough time, they can dismember and consume prey even larger than themselves," Ceccarelli said.



Shaggy Shark
A  tasseled wobbegong blends into its surroundings, assisted by reticular  markings and intricate skin flaps that break up the outline of its  flattened body.
Even  though it's easy enough for a wobbegong to devour a big meal,  scientists are unsure how the animal manages to process prey as large as  other sharks.


"There's  been very little work done to establish exactly how wobbegongs digest  their prey," Ceccarelli said. "Most sharks swallow their prey whole, so  with a mouthful like [a whole other shark], digestion could take several  days."