First known 'vegetarian' shark discovered

New York, Sep 7 Scientists have identified the world's first known omnivorous shark species, which consumes upto 60 per cent of seagrass.

Experts from the University of California-Irvine and Florida International University in Miami decided to investigate the bonnethead sharks' dietary habits after reading reports of them munching on seagrass, reports Xinhua news agency.

The bonnetheads, one of the smallest member of the hammerhead family, are abundant in the shallow waters of the Americas, where they usually feed on crab, shrimp, snails and bony fish.

In the study, five bonnethead sharks were fed on a three-week diet of seagrass and squid. 

A series of tests indicated that the fish successfully digested the seagrass with enzymes that broke down components of the plants, such as starch and cellulose.

All of the sharks put on weight over the course of the study.

The findings, published on Thursday in the Proceedings of the Royal Society B, overturn the idea that all sharks are exclusively meat-eaters and have a "carnivorous gut".

"We were absolutely surprised to find that the bonnethead sharks were taking an omnivorous digestive strategy," Samantha Leigh, the study's lead author, told Fox News on Thursday.

"We have always thought of sharks as strict carnivores, but the bonnethead is throwing a wrench into that idea by digesting a fair amount of the seagrass that they consume."