Scientists Baffled by Shark's Unusual Meal
A group of scientists from James Cook University, including PhD student Nicolas Lubitz, witnessed a tiger shark regurgitate an intact porcupine while tagging hundreds of marine wildlife creatures off Orpheus Island, between Townsville and Lucinda in northern Queensland, in May 2022, according to The Guardian. The researchers were taken aback by the shark's unexpected behavior.
Porcupine's Journey and Shark's Digestion
Lubitz theorizes that the porcupine likely swam between islands through a narrow channel, possibly in search of food or a mate, and was unfortunately caught by the large tiger shark. "I was quite surprised because it's never been recorded before. I didn't think sharks would eat porcupines regularly," said Lubitz.
Lubitz studies the movement and behavior of large sharks around the coastline, investigating the connection between available prey and climate change. He suspects that while sharks may consume porcupines opportunistically, the regurgitated porcupine was more likely a stress response due to being captured and tagged. The porcupine was intact with no signs of digestion, suggesting it had only been swallowed an hour or two prior.
Tiger Shark Diet and Feeding Behavior
Tiger sharks, which can grow up to six meters long, are responsible for the second-highest number of attacks on humans globally, after great white sharks. They have dark vertical stripes on their backs and sides and are scavengers that feed in shallow waters. Despite being known to consume human refuse, this is thought to be the first documented case of a tiger shark eating a porcupine. According to Lubitz, tiger sharks have serrated teeth, and whether they chew their prey or swallow it whole depends on its size. "A large tiger shark can swallow a porcupine whole. They can crush the shell of a turtle and tear it apart with their teeth," said Lubitz.
Wider Implications
The researcher, who works for marine research organization Biopixel Oceans, notes that tiger sharks are opportunistic predators that will consume whatever they can overpower or that is nutritionally rich. The sharks migrate seasonally into temperate waters and are common in south-west Western Australia and southern New South Wales.
Last year, the team caught another tiger shark that regurgitated a meal of fat and vertebrae from a juvenile dugong. According to Lubitz, the tiger shark's consumption of the porcupine carcass highlights a previously underappreciated connection between terrestrial and marine food webs.
Summary
Scientists were surprised to witness a tiger shark vomiting up an intact porcupine. The porcupine's appearance suggests it was recently captured and may have been a stress response to the shark's tagging. This incident highlights the diverse and often unexpected feeding behavior of tiger sharks and the complex connections within marine food webs.