The Omnivorous Sharks That Eat Grass

The Bonnethead Shark, a diminutive species that reaches up to 3 feet in length, lives in the shallow sea grass meadows off both coasts of the Americas. It eats small squid and crustaceans ferreted from the swaying underwater fronds. But, researchers who have carefully monitored everything going in and out of captive bonnetheads say in a study published in Proceedings of the Royal Society B that they also eat large quantities of seagrass. The grass isn’t just passing inertly through the sharks’ guts. They extract nutrition from it just as they do from the meaty portion of their diet. These sharks must, therefore, be reclassified as omnivores — the first omnivorous sharks known to science.