First known omnivorous shark species identified

60% of the bonnethead shark’s diet is made up of seagrass, which they happily graze upon as well as eating fish, crabs, snails and shrimp

Ian SampleScience editor

Wed 5 Sep 2018 00.01 BSTLast modified on Wed 5 Sep 2018 02.50 BST

It is one of the most radical rebrandings in history: contrary to their bloodthirsty image, some sharks are not irrepressible meat eaters, but are happy to munch on vegetation too.

According to US researchers, one of the most common sharks in the world, a relative of the hammerhead which patrols the shores of the Americas, is the first variety of shark to be outed as a bona fide omnivore.

The bonnethead shark is abundant in the shallow waters of the eastern Pacific, the Western Atlantic, and the Gulf of Mexico, where they feed on crab, shrimp, snails and bony fish. Though small by shark standards, adult females – the larger of the sexes – can still reach an impressive five feet long.

Scientists at the University of California in Irvine, and Florida International University in Miami, decided to investigate the sharks’ dietary habits after reading reports of the fish chomping on seagrass, the flowering marine plant that forms subsea meadows in some coastal waters.

“It has been assumed by most that this consumption was incidental and that it provided no nutritional value,” said Samantha Leigh, a researcher on the team. “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.”

Read on 

Scientists have found a shark that can survive on a mostly vegetable diet

Bonnethead species is able to survive on a diet of plants, despite reputation as a predator

Josh Gabbatiss Science Correspondent 

Bonnethead sharks were experimentally fed with a diet of 90 per cent seagrass, which they were able to digest YouTube/Science Magazine

A species of shark that is able to survive on a diet consisting largely of plants, has been identified by scientists. 

Despite their reputation as carnivores Bonnethead sharks were able to survive when they were fed a diet of seagrass, a plant that grows on the ocean floor.

The study, led by Samantha Leigh, a doctoral candidate at the University of California, Irvine, built on research conducted 10-years ago, which examined the creatures stomach contents.

That study revealed large quantities of seagrass. In some young sharks, scientists found over 60 per cent of the material in their stomachs was plant-based.

In order to establish whether sharks were intentionally feeding on plant material, or whether it was accidental, Ms Leigh and her colleagues fed captive sharks a 90 per cent seagrass diet for three weeks. The final 10 per cent was made up of squid. 

Continued  

Scientists have found a shark that can survive on a mostly vegetable diet

Bonnethead species is able to survive on a diet of plants, despite reputation as a predator

Josh Gabbatiss Science Correspondent 

Bonnethead sharks were experimentally fed with a diet of 90 per cent seagrass, which they were able to digest YouTube/Science Magazine

A species of shark that is able to survive on a diet consisting largely of plants, has been identified by scientists. 

Despite their reputation as carnivores Bonnethead sharks were able to survive when they were fed a diet of seagrass, a plant that grows on the ocean floor.

The study, led by Samantha Leigh, a doctoral candidate at the University of California, Irvine, built on research conducted 10-years ago, which examined the creatures stomach contents.

That study revealed large quantities of seagrass. In some young sharks, scientists found over 60 per cent of the material in their stomachs was plant-based.

In order to establish whether sharks were intentionally feeding on plant material, or whether it was accidental, Ms Leigh and her colleagues fed captive sharks a 90 per cent seagrass diet for three weeks. The final 10 per cent was made up of squid. 

Continued