With over 500 species of shark, it would be challenging to list the food habits of each and every one. The great white eats seals and sea lions, the cookiecutter shark takes bites from much larger animals and the tiger shark is known as the ‘rubbish bin of the sea’ because it will eat almost everything!
From the 15-ton whale shark to the 15cm dwarf lanternshark, diets vary dramatically, so here’s the answer to perhaps the most common question of them all. What do sharks eat?
The Diversity of the Shark Food Chain
Broadly speaking, the shark food chain can be split into two categories – the carnivores and the planktivores. Over the half-billion or so years in which sharks have been roaming the seas, their diets have evolved and adapted to suit their size and environment. This has led to some being picky about what they eat and some, known as ‘non-selective feeders’ that will eat anything, including inorganic human rubbish.
The stomach contents of one captured tiger shark in the 1990s suggested it tried to eat a car! Alongside fish, squid and lobster in it’s stomach, there was in fact a number plate and most of a tyre.
The diet of carnivorous sharks includes shrimp, fish, squid, sea turtles and crustaceans like lobster and crab. The bigger sharks will also eat marine mammals like dolphins, seals and sealions and even smaller sharks. Some sharks will even come up to the surface to catch seabirds.
The carnivores are skilled hunters and will often use complex strategies to snare their prey. The great white shark goes straight in for the kill, attacking at speed and brutally tearing at the flesh with 300 razor-sharp teeth. The thresher shark uses its incredibly long tail to stun its prey. The sawshark latches onto its prey with suction-like lips and violently twists it’s catch. Other sharks use ambush or camouflage tactics to catch their prey. These sharks – like all sharks in fact – have a cartilaginous skeleton which helps deliver their immense power without the heavy weight of a skeleton like ours (so if you were wondering how many bones sharks have then the surprising answer is none at all!)
We can answer another common question about the diet of sharks – do sharks eat whales? They do, but only a select few apex predators are physically capable of hunting down and eating whales including the great white, tiger shark and bull shark.
Planktivores – also known as filter-feeders – use a suction process to take in water and filter plankton, including fish eggs, krill, crab larvae and tiny fish. They feed this way because their teeth are small and blunt – but make no mistake, even though what they eat is tiny, they get through a huge amount. For example a 10 metre, seven tonne basking shark can filter around 2,000 cubic metres of water an hour, enough to fill an Olympic-sized swimming pool, to extract 2kg of food.
How Much Food do Sharks Eat?
We’ve answered the question ‘what do sharks eat’, but just how much do they eat? Because they are cold-blooded animals, they burn energy at a far slower rate than warm-blooded animals so they don’t need to eat as much as you might think.
Some will gorge on food and then rely on the oil stored in their liver so they don’t have to eat for weeks but generally speaking, sharks will eat between 1% and 10% of their body weight in a week, usually condensed into one or two meals. Their digestion and metabolic rate is extremely slow so they don’t have to eat as regularly as humans do.
Do Sharks Eat Humans?
Don’t worry, we’re not part of a shark’s diet. Of the 500+ species of shark in the sea, only around 15 have been involved in attacks on humans but the intention is not for food. Sharks evolved millions of years before humans so we’ve never been part of the shark food chain and it seems they will only attack if they’re curious, confused or feel intimidated. After an attack a shark will usually disappear very quickly. It’s also been suggested that to a shark, humans taste disgusting!
Conclusion: What Sharks Eat
A shark’s diet is as wide-ranging as there are sharks in the sea, but nevertheless the understanding of a shark’s diet remains a fascinating subject. With such a wide range of sharks and variety of diet, the question of ‘what sharks eat’ certainly highlights the huge variety of astonishing sharks that roam the oceans today. From carnivorous sharks eating sea lions and even whales to filter-feeders scooping up microscopic meals, the range and diversity of a shark’s diet is boundless.