Whale sharks are the largest fish in the sea, though as filter feeders, they don’t have the same bloodthirsty reputation as their kin. Still, they are sharks, so it’s long been believed these gentle giants rely almost exclusively on animal protein.

That’s not what an intriguing new study published this month in the journal Ecological Monographs found, though. Careful investigation of blood and tissue samples from over a dozen whale sharks suggests that they actually have a pretty omnivorous diet that includes plants and algae.

The research team, led by University of Tokyo biologist Alex Wyatt, used a combination of samples from captive and wild sharks to demystify the feeding habits of these enigmatic ocean travellers. While previous studies had