Sharks, the ocean’s ancient navigators, possess a majestic form matched only by the grace of their movement. The streamlined bodies of these creatures are marvels of evolutionary design, allowing them to glide effortlessly through the water with predatory precision. From the great whites, with their formidable jaws and swift, powerful tails, to the ethereal dance of hammerheads moving in sync, sharks embody a perfect balance of power and elegance. Their undulating movements, driven by muscular, flexible bodies, enable them to burst into action with astonishing speed, making them both awe-inspiring and formidable.

Dr. Mike Heithaus, a renowned shark scientist, has extensively studied these fascinating beings, uncovering the secrets behind their sophisticated hunting techniques and their crucial role in marine ecosystems. His insights have not only advanced our understanding but also highlighted the urgent need for their conservation.

In Shark vs. Ross Edgley (premiering June 30) Ultra-athlete and shark advocate Ross Edgley goes head-to-head against four of the ocean’s most formidable sharks.

Can you describe the typical diet of a tiger shark? What are some of the most common prey items they consume?

Tiger shark diets can be pretty variable and tend to reflect the types of prey they might find in a particular place.  They don’t seem to be very picky though, and will eat fish, rays, small sharks, sea turtles are a favorite, sea birds, sea snakes, dugongs (a sea cow) when they can catch them, and even dolphins.  They will also scavenge whenever they get the change.  Fish is the most common prey usually but sea turtles are another common prey – their teeth are perfect for cutting through shell.

How much does a tiger shark typically eat in a single meal? Are there variations based on age or size?

We really don’t know and it depends on what food is around.  If there is a dead whale or they have captured big prye they will probably fill their stomachs, but how much that is will depend on the size of the shark.  For really big tiger sharks that could be well over 20kg I suspect.  The problem is we just don’t have measurements of this for sharks in the wild, but we do know that they will completely fill their stomachs some times.

Can you discuss what exactly you and Ross Edgley were doing when you had the shark take a massive bite out of the gigantic gelatine lollipop.

The gelatine lollipops are a technique we use to get information on the bite characteristics of tiger sharks and other species, but in this case we used it to get an idea of just how much a tiger shark might be able to tear off a large carcass in a single bite.  From that we could make some guesses about how much they might be able to eat in a single meal and, if the meal was whale, how many calories they might consume.

What have you discovered about the feeding patterns of tiger sharks in different regions? Are there specific areas where their diet changes significantly?

Scientists working around the world on tiger sharks find quite different diets based on what food is available there.  In some areas they live up to their reputation of eating just about anything they can get their mouths on.  In others, they seem to key in more on a smaller number of prey types.  And what they focus on may change seasonally.  For example, they will show up off northeast Australia to take advantage of huge turtle numbers during the nesting season and probably eat mostly turtles.  During the rest of they year they would eat more broadly.  In northwestern Hawaii some tiger sharks will cue in on the baby albatross that are trying to learn to fly and often end up in the water.  When the albatross aren’t fledging the sharks have to find other food sources.

Can you explain the process by which tiger sharks hunt and capture their prey? Do they have any unique hunting strategies?

Tiger sharks aren’t particularly maneuverable so it appears that they do best when they can get close to prey and catch it with a quick burst of speed.  In Australia, we found tiger sharks swimming near the bottom, probably looking for prey up at the surface, and then swimming up to the surface.  When they dropped to the bottom they sometimes tried to make rushes at prey on the bottom by ambushing from above.  In general, though, scientists have observed very little foraging behavior in tiger sharks (when they aren’t finishing off a meal they already caught or happened across) so there are probably a lot of tactics they are using that we haven’t ever seen.

Could you share some insights from your research on how often tiger sharks need to eat to maintain their energy levels?

This really depends on the size of the shark and how big of a meal they have had.  Larger sharks can go longer between meals and if a tiger shark has filled its stomach, it can probably go weeks without eating.  But, if it sees a potential meal it is unlikely to pass up an opportunity even if it doesn’t necessarily need to eat.

What challenges do you face when studying the diet and feeding habits of tiger sharks, and how have you overcome them in your research?

Most of what we know about tiger shark diets comes from scientists examining what is in the stomachs of sharks that have been taken in fisheries or in nets.  Newer techniques, like using DNA barcoding  of swabs we can take to get waste products are being developed to help us get more data on what they are eating.  We also have been using cameras that we can attach to sharks to observe their behavior.  Unfortunately, these are really expensive and hard to get on and get back so the data come in very slowly.  To continue to piece together how tiger sharks forage and more about their diets we just need to put in a lot of time in the field and use all the techniques we have available.  Also, I hope to see more long-term studies of tiger sharks happening all over the world, since that prolonged effort tends to be what we need to learn the most interesting and important things about these incredible sharks.

IMAGE CREDIT: National Geographic/Nathalie Miles