Do Sharks Eat Jellyfish?

Do sharks eat jellyfish?

Sharks are varied and prolific ocean predators that come in all shapes and sizes. And so does their food.

Sharks can eat fish, mammals, crabs, and even vegetables! But what do they think of sharing their space with jellyfish?

Jellyfish are even more dangerous to humans than sharks – the box jelly alone kills more people in the Philippines than sharks do worldwide.

They’re also pretty devoid of nutrients, comprising 95% water. So, who would really want to eat one? And do sharks eat jellyfish?

Some sharks will eat almost anything. The Tiger shark, for example, is a species of shark that’ll chow down on a jellyfish. But whale sharks have also been known to swallow the small ones whole.

So why do animals eat jellies? And how do they manage not to get stung?

Why do Animals eat Jellyfish?

One thing to note about jellyfish is that they’re packed full of water.

While this might seem like a great opportunity to rehydrate for a thirsty sea animal, jellies are osmoconformers, which means the salt content of their bodies matches with the salinity of the sea.

Simply put, they’re basically made of seawater. This further increases the mystery of why anything would want to eat one. But many animals do!

There are three major reasons why animals might eat a jellyfish.

  1. Jellyfish are slow – they don’t move much, so it doesn’t really require any energy to hunt one down. Quantity compensates for quality, and a large sea turtle can graze on these helpless jellies until they’re stuffed.
  • Jellyfish are everywhere – they float around in some of the most barren parts of the ocean, often in areas with no other residents. Because of this, they’re about the only thing to eat for some far-reaching, pelagic animals.
  • Some animals eat anything – be it on purpose or by accident, lots of animals gobble up whatever’s small enough to swallow. This includes filter-feeding sharks and opportunistic hunters.

What is the Natural Predator of Jellyfish?

Jellyfish have quite a lot of natural predators.

Usually armored sea-tanks like green and leatherback turtles or hermit crabs, but some other, softer predators include birds, sunfish, and even humpback whales.

Animals that eat jellyfish will either have in-built sting protection or will bite off chunks of the safe part to avoid getting stung.

Since jellyfish are mostly water, there’s not much nutritional benefit from eating only one, and leatherbacks can grow up to 2000lb, so they need a lot of jellyfish! In fact, they can eat almost ¾ of their body weight in jellyfish every day!

leatherbacks turtle
U.S. Fish and Wildlife Service Southeast Region, Public domain, via Wikimedia Commons

Turtles have spiny protrusions all the way down their throats to help push jellies into their bellies. These papillae also protect the turtle from stings.

The ocean sunfish is the world’s heaviest fish. These dopey-looking weirdos can’t move very quickly, so jellyfish present an easy target for them.

Big sharks are also thought to take on jellyfish. Tiger sharks, as we mentioned, will eat just about anything, jellyfish included.

What Shark can eat Jellyfish?

Tiger and bull sharks are not fussy eaters. They’ve been found with license plates, fur coats, and, ominously, video recorders inside them.

So it’s hardly surprising that they’ll eat jellyfish. Other ocean-going or pelagic sharks from the lamniformor Mackerel sharks, family are thought to nip up the occasional jelly too, but there isn’t much data on that yet.

While it might be possible to imagine a vast ocean is teeming with life, most animals spend time in shallow water, around reefs or shorelines. The farther out you go, to more desolate it becomes.

Some types of sharks spend time migrating through these ocean deserts, and because jellyfish are at the mercy of the currents, they may be the only food available. Hence, pelagic sharks are likely to eat them.

The gentle Whale shark might be a little pickier, but not by much. Little jellies go down just as easily as plankton and krill, even some squid and small vertebrates. But these slow-moving sea sweepers have enormous mouths, so it’s probably quite difficult to avoid swallowing some jelly here and there.

For the same reason, it’s safe to assume that the other massive filter-feeders will also eat jellyfish occasionally, though perhaps not by choice. The megamouth shark and the basking shark certainly have the jaws for it.

Do plastic bags looks like jellyfish?

Plastic bags and sheeting floating around the oceans are often mistaken for jellyfish by their natural predators.

In fact, plastic bags are some of the most common forms of plastic pollution ingested by sharks.

Ingestion of plastic debris affects nutrient absorption, toxifies the shark’s tissue, and can block and damage the digestive system.

Plastic can also get tangled around the gills or body, restricting the ability to breathe or move properly and resulting in a slow and unpleasant death.

Even if a jelly-hunter avoids eating bags by mistake, the mucous membranes of a jellyfish attract and collect microplastics and plastic debris floating in the ocean, and the jelly can even ingest these, thinking they’re food. This means that jellyfish predators are going to get plastic inside them one way or another.

For plastic pollution, everyone is complicit.

Governments are taking small steps to curb the littering of the ocean, but it’s not nearly enough.

Ocean Society suggests that we can reduce single-use plastics, recycle where possible, and participate or organize your own beach clean-up events if you want to help out.

Do Sharks get Stung by Jellyfish?

Sharks have incredibly specialized skin that reduces drag and protects them from predators. This skin also renders them completely immune to jellyfish stings!

Now, you’re sure to know about the teeth on the front end of these fish, but when you look at sharks’ skin under a microscope, you might be surprised to find that their entire body is also covered in teeth – or tooth-like structures called denticles.

These denticles are covered in enamel (like teeth) and are responsible for a lot of the protection that a shark gains from its skin.

Dermal denticles are extremely hard and strong, and it’s no wonder the microscopic barbs from a jellyfish’s sting can’t penetrate them.

Conclusion

So, sharks do eat jellyfish. At least, some do. But it’s not very clear why they do it. Jellyfish are mostly made of saltwater and a little bit of proteins.

Typically, slow-moving marine animals will use them as an easy snack, but often, sharks are opportunistic feeders, and some species spend long periods far out to sea, where there isn’t much else to eat.

Other sharks swim around with their mouths wide open, scooping up anything small enough.

Regardless, with all the plastic bags floating about in the ocean, plenty of sharks and other jellyfish predators like turtles are suffering from mistaken identity and will get bellies full of plastic at best or tangled up and drowned at worst. Plastic pollution in the ocean comes from irresponsible uses on land, so if we can become more considerate of what we use and where we throw it, we will be doing sharks and marine life a big favor!