What Do Jellyfish Eat? (Jellyfish Diet & How Do They Eat)

Jellyfish diet what do jellyfish eat

Jellyfish are truly fascinating sea creatures. Behind their strangely cute and peaceful appearance, jellyfish are actually opportunistic feeders, munching on various foods.

Depending on the species, jellyfish may have varied diets. They may feast on plankton, crustaceans, small fish, plants, and sometimes other jellyfish. Larger species might even tackle a crab or lobster. Interestingly, some nurture algae in their system, benefiting from the nutrients of photosynthesis.

If you want to learn more about what jellyfish eat and how they eat, stick around. This guide covers everything about the jellyfish diet and feeding. Let’s start!

What Do Jellyfish Eat?

The jellyfish diet is varied and is mainly influenced by various factors, such as the availability of food sources, their life stage, and species. Nevertheless, here are the common foods jellyfish eat in the ocean:

1. Plankton

Plankton drifting in the ocean

Planktons are essential components of the jellyfish’s diet. These are tiny organisms that drift in the vast oceans and seas. They can be microscopic plants (phytoplankton) or tiny animals (zooplankton),

These tiny organisms are readily available and easy for jellies to consume. As these creatures float near the sunlit surface, they become effortless for jellyfish to trap using their tentacles as they move through the waters. 

The plankton diet includes minuscule creatures like copepods, amphipods, and even the tiniest shrimps and krill.

Interestingly, jellies are also considered zooplankton, animals that drift in the marine world, relying heavily on ocean currents for movement.

2. Small Fish and Larvae

School of fish swimming underwater

Small fish and their larvae also provide a perfect blend of proteins and essential nutrients for jellyfish.

Jellies catch small fish by spreading their tentacles as they drift in the ocean. When an unsuspecting fish enters the trap, the stingers immobilize it, making it an effortless meal.

Fish eggs are another favorite for these drifting predators. Apart from small fish, some jellyfish species consume larvae of crabs and shrimps.

3. Other Jellyfish

Jellies swimming in the sea

Jellyfish may occasionally resort to a behavior that may seem surprising: eating other jellyfish. While this isn’t common, certain circumstances can lead them to consume their kind.

Larger jellyfish might eat smaller ones from a different species or their offspring. However, this behavior is often a last-resort tactic.

This behavior is typically observed when prey is hard to come by, forcing the jellyfish to sustain itself by any means possible, even if it means resorting to cannibalism.

An example of a jellyfish that eats other jellyfish is the Fried Egg Jellyfish (Cotylorhiza tuberculata).

4. Crustaceans and Mollusks

Rockpool shrimp at the bottom of the sea

Crustaceans and mollusks are also part of the diverse diet of jellyfish. 

Like small crabs and shrimp, crustaceans are often trapped by jellyfish tentacles, paralyzed by their stingers, and then consumed.

Mollusks, particularly the softer varieties, can also be on the menu. While these invertebrates might seem tough prey, many jellyfish species are well-equipped to digest them.

However, it is worth noting that not all jellyfish species eat crustaceans and mollusks.

5. Photosynthesis

Group of jellyfish interactiing with sunlight

Photosynthesis usually involves plants converting sunlight into energy. But did you know some jellyfish benefit from it, too?

A few jellyfish species, such as the Cassiopea Jellyfish (Cassiopea sp.) and Golden Jellyfish (Mastigias papua etpisoni), host tiny algae called zooxanthellae in their tissues.

These algae use sunlight to produce food, a process called photosynthesis. In return, the jellyfish gain some nutrients from the algae. 

This partnership lets jellyfish access energy uniquely, supplementing what they capture from the sea.

During our field research in the Indo-Pacific to observe and document the different types of angelfish inhabitants, we were lucky to come across a cluster of Golden Jellyfish basking under the sun.

It was really amusing how these jellies follow the sunlight to nourish the algae in their systems for photosynthesis.

What Is a Jellyfish’s Favorite Food?

When discussing a jellyfish’s “favorite” food, it’s essential to understand that their preferences are driven by survival rather than taste. Jellyfish are opportunistic feeders, meaning they eat what is available.

Since they cannot actively hunt and chase their prey, they rely on what food resource is more accessible.

The primary diet for most jellyfish species is plankton, particularly zooplankton. These tiny organisms are abundant in marine environments, making them a readily accessible and consistent food source for jellies.

How Do Jellyfish Eat? Feeding Mechanism of Jellyfish

Jellyfish capturing a small fish

Jellyfish, despite appearing simple organisms, have effective feeding mechanisms developed over millions of years. Most jellyfish species can sting, which they use to catch food.

Their tentacles, equipped with stinging cells, are their primary tool in catching prey. Once they’ve immobilized their catch, they move it towards a small opening, their mouth, located at the base of their bell-shaped body.

This tiny mouth is directly connected to their stomach, allowing the prey to be ingested quickly. Inside, a cavity called the coelenteron takes on the role of digestion.

Unlike many animals, jellyfish lack organs like the liver or intestines. Instead, their coelenteron produces enzymes that break down food.

Once digestion is complete, waste is expelled through the same opening they eat from. This process is efficient and swift, as they must clear out food remnants before consuming their next meal.

Though basic compared to more advanced creatures, their system has ensured their survival for hundreds of millions of years.

How Do Jellyfish Get Their Food?

Jellyfish have been around for millions of years and have a fascinating way of getting food. How they hunt and eat depends mainly on their life stage.

When jellyfish are in their earliest stage, called the larva stage, they emerge from eggs. These tiny larvae search for a place to attach themselves. Once they find it, they become small polyps, sticking to surfaces like rocks.

Being immobile, they can’t actively hunt. Instead, they depend on whatever small bits of food drift their way. At this phase, they’re not hunters but opportunists, feeding on tiny organisms that come close enough.

The polyp stage is a growth period for jellyfish. As they mature, some polyps bud off into another stage called ephyra. These are like mini-jellyfish. They are mobile, enabling them to start trapping food sources.

The final and most recognized jellyfish form is the “medusa.” It’s this stage that we often picture when we think of jellyfish — with their bell-like shape and long tentacles.

Some species of adult jellyfish, like the infamous Box Jellyfish (Cubozoa), have tentacles equipped with stinging cells. These cells release venom, allowing the jellyfish to paralyze its prey.

Some jellyfish species are so venomous that they can be lethal to humans. If you are stung by a stinging jellyfish, especially a Box Jellyfish, you should immediately seek professional medical care.

Jellyfish don’t chase their food. Their method is simple yet effective. Floating in the water, they spread their tentacles wide.

Any small fish, tiny crabs, or other jellyfish that drift into this trap get stung and immobilized. The jellyfish’s tentacles then guide the food to its mouth.

In essence, jellyfish have perfected the art of passive hunting. They drift and let their prey come to them, making the most of their environment and bodily capabilities.

Watch this video of a Portuguese Man O’ War Jellyfish stinging its prey:

How Portuguese Man O' War stings and eats prey | Blue Planet II

Factors Influencing Jellyfish Diet

Group of Jellyfish in the ocean

The diet of a jellyfish isn’t just random; various factors influence what they eat. Understanding these factors can give us a better idea of their dietary habits.

Here are a few factors that influence the jellyfish diet:

  • Life Stage: Jellyfish go through different life stages, from larva to adult. At each stage, their dietary needs and habits vary. Younger ones might feed on small particles, while adults may be able to trap bigger prey.
  • Prey Availability: Jellyfish rely on what’s available. If there’s an abundance of a particular prey in their area, that becomes their primary food source. In nutrient-rich waters, they might find plenty of plankton. In other regions, they might feed more on small fish or jellyfish.
  • Jellyfish Species: There are many types of jellyfish, each with its unique preferences. Some might be more inclined to eat certain types of prey over others. Moreover, not all jellyfish have potent venom or long tentacles. Their physical attributes can limit or enhance their ability to capture certain prey.

Jellyfish are highly adaptable creatures, seamlessly adjusting their diet based on various factors. They are ocean creatures that have survived millions of years by evolving and adapting.

Final Thoughts

Jellyfish, with their simple yet mesmerizing structure, play a vital role in marine ecosystems. Their diets vary widely, influenced by various factors.

From microscopic organisms during their larval phase to small fish as adults, their adaptability in food choices showcases their resilience and evolutionary success.

By understanding the intricacies of their feeding habits, we gain valuable insights into their behavior and ecological significance.

Besides what jellyfish eat, there are more fascinating things about these creatures! Comment below if there are other facts you would like to know about jellyfish.

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