Shark Week, Shark diving, Jaws, Baby Shark… our insatiable fascination for the coolest fish around knows no bounds. So it’s slightly surprising that we’re still discovering things about the various shark species out there, especially when it comes to their notorious diets.
We’ve long known sharks to be carnivores, although some types have more blood-thirsty reputations than others (here’s looking at you, great whites). But as scientists discovered recently there is indeed one species that prefers to surprisingly round out its seafood buffets with some veg: the bonnethead (or shovelhead) shark.
The species, which is a smaller relative of the hammerhead shark, has been discovered to be the first omnivorous shark in existence—previously scientists believed the creatures ate seagrass by accident while tearing through other, meatier options. The theory was that the ingested greens were passed through the gut without proper digestion.
Now, thanks to further research, it’s believed these sharks actually eat seagrass as a regular part of their diet—up to 62 per cent of it, in fact. Tests showed that in reality, the fish may be as good at digesting vegetable matter as omnivorous young green sea turtles, making plants a potentially important part of their overall diet.
“It has been assumed by most that this consumption was incidental and that it provided no nutritional value,” said study co-author Samantha Leigh. “I wanted to see how much of this seagrass diet the sharks could digest, because what an animal consumes is not necessarily the same as what it digests and retains nutrients from.”
To come to these findings, researchers fed bonnethead sharks meals consisting of 90 per cent seagrass and 10 per cent squid over a three-week period. They then analyzed how many nutrients the animals digested versus how many they excreted. As it turns out, the sharks were still able to gain weight on a mostly plant-based meal plan.
“Bonnethead sharks are not only consuming copious amount of seagrass but they are actually capable of digesting and assimilating seagrass nutrients, making them clear omnivores,” the researchers wrote in the journal Proceedings of the Royal Society B. “This is the first species of shark ever to be shown to have an omnivorous digestive strategy.”
Omnivorous or not, you still won’t catch us going for a free-swim with these animals. We’ll leave that to professionals and people in cages… or maybe those cute kids from Baby Shark.