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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 want to know about the eating habits of the little fellas.
Contents
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!
Jellyfish are extraordinary animals.
They are unique in that they have a very simple nervous system compared to other types of animals and humans. 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 deeper and look at the answer in more detail.
As we looked at in the introduction to this article, the jellyfish will not actively search for 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 tthatat capture 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 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 eventually 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 and move it up to the mouth. The mouth is placed in the animal’s center and directly coupled to the stomach.
The mouth looks mostly just like a little hole. It’s a simple mouth that will only do some barely, directing the food into the stomach and shooting out water 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 was 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 its so-called “coelenteron,” which does 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 spat out again.
The jellies have no blood or vessels, so there’s no real circulation system.
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 fast food because they can’t swim around with stuff inside them. But This also makes sense because they only eat tiny stuff, so there’s not much to digest.
WHAT do Jellyfish Eat?
This depends on the size of the 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 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 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 small and have 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 float around in a big fog of unconsciousness.
Lots of jellyfish are swimming together, and 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 must wait until 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 triggers it by touching the extremely long tentacles floating around itself.
Once it happens to capture and kill an animal (or knock it unconscious), it will try to get 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 jellyfish.
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 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 Jelly’s themselves are also constantly in danger of being eaten by animals such as:
- Spadefish
- Sunfish
- Sea Turtles
- Other Jellyfish
- Humans(!)
As we just mentioned, humans also consider some jellies delicate meals.
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 to Georgia in the U.S.
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 get shipped.
According to Wikipedia, Mexico harvested 20,000 tons of jellyfish (equivalent to US$3.5 million) over a period of only three months.
Related questions
How many Jellyfish types are there?
There are more than 200 known species of jellyfish. Some are bigger and some are small. Most of them are not dangerous to humans but they can still cause irritation if you touch the tentacles.
Source: dnr.sc.gov