Sharks are known to have big appetites, most likely for big preys. However, a new study found that the big marine animal likes its meals small and its prey bite-sized.
Apex predators are those at the top of the ecosystem such that no other species are able to prey on it. These animals are commonly big in size and ferocious in behavior. Experts consider reef sharks as apex predators because of their massive size, but the species' functional role has not yet been established.
To evaluate the reef sharks' assumed role, scientists from James Cook University reviewed the contents of a reef shark's stomach and compared these with those of other types of sharks and big marine predators.
Inside A Shark's Stomach
The researchers, led by Ashley Frisch, pumped a shark's stomach to determine what it has eaten for its last meal. They were stunned to find out that there was a wide array of prey inside, with nothing really common among them.
Frisch says that this may mean that these types of sharks eat small meals opportunistically and in long intervals.
The authors also performed a chemical investigation of sharks' body tissues to determine what the animal had been eating over longer periods of time.
The results show that the chemical structure of the tissues were much like other large reef fishes such as snappers, emperors and groupers. This means that both reef sharks and large fish species have the same diet, but do not feed on each other. Instead of eating big fish, reef sharks forage like smaller fish.
Marine Food Chain
The study also raises an important question about the food webs of coral reefs. The new information serves as a reminder that large animals cannot always be considered apex predators merely due to their size.
"We now know that reef sharks are an important link in the food chain, but they are not the last link in the food chain," says co-author Justin Rizzari. Examples of most common top predators according to him are hammerhead sharks, tiger sharks and people.
Coral reef ecosystems are complicated, but they need adequate protection. As studies like this surface, more and more information about the importance of each and every species becomes clear.
The study was published in the journal Coral Reefs.