"Bonnetheads are capable of digesting components of seagrass, with similar effectiveness to omnivores, making them the only shark species known to have the ability to digest plant material".
The study authors, from the United States, were unsure if the shark could actually digest the seagrass.
However, the ecological implications of 4.9 million bonnethead sharks eating up on seagrass are not yet fully understood. A small hammerhead, which belongs to the sharks, in the absence of "meat" without any problems and eats plant food.
Researchers from the University of California, Irvine in the U.S. found that bonnethead sharks happily graze upon seagrass, in addition to eating bony fish, crabs, snails and shrimp. In fact, it turns out that up to 62 percent of their diet is made up of seagrass, from which they absorb a great deal of nutrients, notes the Smithsonian website.
As the seagrass took root, the researchers added sodium bicarbonate powder made with a specific carbon isotope to the water.
The Guardian reported that up to 60% of the bonnethead shark's diet is seagrass.
"Until now, most people thought that seagrass consumption was incidental when these sharks were hunting for crabs, etc. that live in the seagrass beds", Leigh said in a statement.
The researchers monitored the bonnetheads for a period of three weeks, during which time they fed the sharks a diet of 90 percent seagrass and 10 percent squid.
The scientists ran a series of tests on the sharks.
The sharks' blood and liver tissue are tested and a carbon isotope added to the seagrass was also found indicating the plant does serve a nutritional goal for the sharks.
"This is the first species of shark ever to be shown to have an omnivorous digestive strategy".
"As green sea turtles mature, they become nearly entirely herbivorous, and their digestibility of seagrass increases".