How Do Jellyfish Eat? (And What Do They Eat?)

Have you ever wondered how Jellyfish eat and how they digest food? We have done a ton of research on the Jellyfish and here’s everything you could possibly want to know about the eating habits of the little fellas.

How do jellyfish eat? The Jellyfish does not actively seek out food. It will capture plankton floats nearby. However, they can propel themselves to attract food. Jellies have 4-8 oral arms to capture food from the tentacles and into their mouth.

But that’s the very short version.

There’s a lot more to say as you will see below. We have found a lot of fun facts and quirky features about the jellies. They are just as crazy and funny as they look!

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Jellyfish are extraordinary animals.

They truly are very unique in the sense that they have a very simple nervous system compared to other types of animals and humans. And they tend to eat anything that comes their way depending on their size.

So it’s fun to study how it manages to do basic stuff like eating and breeding.

HOW do Jellyfish eat?

Let’s dig a step deeper and look at the answer in more detail.

As we looked that in the introduction to this article the jellyfish will not actively search out food. It will passively float around and feed on any plankton type of food that floats by it.

It doesn’t have a brain so it depends on more mechanics and basic things to feed.

Here’s how it’s done in more detail:

1) First, the tentacles will catch the food

The jellyfish has long tentacles which are used to capture the food in the first place.

Plankton will pass by the animal and once it does it will stick to the tentacles. These tentacles can reach up to 100 feet (!) (3 meters) for some species.

It’s a rather passive process(remember that it has no brain) where the Jellyfish just happens to float into these little bits and pieces of food by an incident.

When the food touches the tentacles it gets poisoned. So if it isn’t dead already it will be soon. First, the little animal will be paralyzed and it’ll eventually be killed so the jellyfish can eat it.

Some of the bigger jellyfish will have a stinging thread curled up inside it which it can throw out towards the prey:

2) The oral arms put the food into the mouth

The oral arms near the mouth will capture that food and transport it into the mouth.

These are much smaller and shorter than the tentacles and will actively grab the plankton etc. and move it the rest of the way up to the mouth. The mouth is placed in the center of the animal and it’s directly coupled to the stomach.

The mouth looks mostly just like a little hole. It’s a very simple mouth that will only do some basic stuff like directing the food into the stomach and shoot out water in order to move the body forward. So the mouth is also in charge of moving the animal around.

3) The digestive system of the jellies

The plankton ended up inside the mouth of that jellyfish, it’s time for the digestion system to take over. Something they have in common with Sea Anemones.

As soon as the food enters through the mouth of the jellyfish it ends up in the stomach. That’s how simple this system is.

The digestive system offered by jellyfish is so simple that it doesn’t even have a liver, pancreas, or intestines!

So how does it digest the food?

It uses it’s so-called “coelenteron”, which is doing the same thing as your stomach and intestines. Here we find a lot of enzymes that will help it digest the food. The food is digested through the cells inside the stomach and the rest is being spat out again.

The jellies have not blood or vessels so there’s no real circulation system in place.

4) There’s no butt!

As a jellyfish eat there will be a waste of course.

But another fun fact about those jellies is that they do not have an anus. So the waste from the food will have to get out the same way it came in: Through the mouth!

As water runs in and out of the Jellyfish, it will take out the “garbage” (feces). Now there’s space for the next piece of food that comes along and gets transported into the mouth. The water circulates food and oxygen around inside the Jellyfish to give it what it needs to live.

5) They eat their food fast

They always eat the food super fast because they can’t really swim around with stuff inside them. But This also makes sense because they only eat tiny stuff so there’s not a whole lot to digest anyway.

WHAT do Jellyfish Eat?

This depends on the size of jellyfish.

So let’s start by dividing all the jellies into bigger and smaller Jellyfish. This is a broad categorization but one we will make in order to be able to explain everything in simple terms.

What do the SMALL jellies eat?

The smaller jellies are what we call “Carnivorous”.

That means, that they feed on all the different tiny organisms you will find floating around in the sea.

These things include:

Plankton
Fish eggs (full of proteins!)
Tiny fish
Plants
+ a ton of other tiny creatures

In areas with a lot of jellies, it can be a problem for the smaller fish because the jellies will eat everything that’s small and has nutrition.

So smaller fish has to go elsewhere to find food if there are too many jellies. That’s not a big problem though, as the fish are much smarter and can quickly figure this out. The Jellies will not follow after them because they are not that smart. They will just float around in a big fog of unconsciousness, so to speak.

And lots of jellyfish are swimming together it’s called a bloom. A Bloom can contain millions of jellyfish and they often cause problems for fish and fishermen. When that happens, you just have to wait till the current carries them in another direction.

What do the BIG jellies eat?

Some of the bigger jellies can actively capture and kill bigger organisms with their poisonous sting, as we mentioned above. It can shoot out this sting whenever an animal will trigger it by touching the extremely long tentacles it has floating around itself.

Once it happens to capture and kill an animal (or knock it unconscious) it will try to get in into the mouth.

These are some of the animals bigger jellies eat:

Lobsters
Shrimps
Barnacles
Crabs
Plants
Other Jellies (!)
etc.

The bigger jellyfish will also be able to eat other jellyfishes.

So it actually has a cannibalistic behavior. But remember it doesn’t have a brain so it’s not really “aware” of what’s coming into the mouth. It has to feed on whatever floats by.

It will basically eat anything that comes by, so even though it has a super-simple digestion system, it’s able to eat a big variety of food!

Who eats the jellies?

The Jellys themselves are also constantly in danger of being eaten by animals such as:

Spadefish
Sunfish
Sea Turtles
Other Jellyfish
Humans(!)

As we just mentioned some jellies are also considered a delicate meal for humans.

The so-called “Cannonball Jellyfish” is sometimes served at expensive restaurants. Especially in Asia where they are part of the booming seafood business.

Jellies are also of great export value for the U.S state of Georgia.

They are being sold to seafood distributors across Japan, China, and Thailand where they will end up on the dining table. They are being dried and packaged before they got shipped.

According to Wikipedia, Mexico harvested 20,000 tons of jellyfish (equivalent to US$3.5 million) over a period of only three months.