Jellyfish are confusing creatures that are known to have dangerous venom. They are transparent and gelatinous and appear to have no organs. So, how do they live, and do jellyfish have brains?
Jellyfish do not have brains. Instead, they have a basic set of nerves throughout their bodies. The nerves can detect touch, temperature, and salinity in their tentacles. Other nerves in their bodies have different functions, such as light and gravity detection. They are mostly comprised of water and aren’t aware they’re alive.
If you want to learn more about jellyfish autonomy, keep reading. We’ll go into more detail about their organs and their purposes.
Let’s dive in.
Do jellyfish have brains?
Jellyfish do not have brains. Instead, they have a basic set of nerves that perform different bodily functions.
These nerves are essential to the survival of jellyfish, as jellyfish have no central nervous system to rely on. If these nerves are damaged, there is a severe risk of death.
They depend on automatic reflexes to respond to stimuli, such as danger or prey. These reflexes include expelling venom when attacked by a predator.
Sometimes these reflexes can fail to protect the jellyfish. Sea turtles have adapted to hunt jellyfish from behind to avoid their tentacles and prevent severe injuries.
Jellyfish are unaware of their existence and do not have a conscious. Since they don’t have a brain to process information, they don’t have thoughts or emotions.
Due to this, they are sensitive, so they don’t have a delayed response before protecting themselves. Because of this, even if you don’t harass a jellyfish, it will still sting you if you are too close.
Their nematocysts are activated at the slightest touch of another organism. They don’t mean to sting humans and aren’t aware that they do.
Jellyfish are not intelligent and have few direct interactions with each other. They often gather in hordes, but it’s unknown why they do this, as they are not social creatures and aren’t conscious.
Do jellyfish have a heart?
Jellyfish do not have a heart. They do not have a circulatory system, which is vital for other organisms such as humans.
As they don’t have blood, they don’t need the heart to pump it around their bodies. Blood is unnecessary for jellyfish as the oxygen they absorb is enough to keep them alive.
Medical research has been inspired and amazed by the jellyfish’s ability to thrive without a heart. Many experiments have been carried out to mimic the structure of a jellyfish, and artificial jellyfish have been built using rat heart cells and silicone.
Jellyfish have had no hearts since the beginning of their existence. Their autonomy has been relatively the same for 650 million years.
Do jellyfish have lungs?
Jellyfish do not have lungs. Instead, they absorb oxygen through their thin skin and store it to allow them to survive in low-oxygen conditions.
Their skin is made of two layers; the outer layer is called the epidermis, and the inner layer is called the gastrodermis. In between these layers is a material called mesoglea, a jelly-like substance.
The mesoglea is a non-living substance released from living cells and does not require oxygen. This means that a jellyfish’s tissue does not need a lot of oxygen.
A jellyfish’s gut can help them improve its oxygen intake. They have a coelenteron, which is the inner space of their gut.
The shape of their coelenteron expands the surface area-to-volume ratio for the gastrodermis. This improves oxygen diffusion and allows all the areas that need oxygen to get it efficiently.
Their mesoglea also store oxygen for the living tissue, allowing them to tolerate low-oxygen environments. This will enable them to hunt for food in areas where other animals wouldn’t survive, resulting in less competition.
Do jellyfish have bones?
Jellyfish do not have bones and consist of water and gelatin. They don’t need bones to keep their shape, as the water’s buoyancy decreases the weight of the jellyfish.
If you have seen a picture of jellyfish on land, you can see that they don’t keep the same umbrella shape they have in the ocean. This is due to the difference in density and causes the jellyfish to collapse on itself.
When they are in the water, having no skeleton aids them in swimming more efficiently. Without a heavier structure, they can float in the ocean with ease.
While this provides benefits for the jellyfish, it also means it is challenging to find fossilized jellyfish. Since they are soft-bodied, fossil records can be biased and deny their history.
Although there is no evidence of fossilized jellyfish from 650 million years ago, scientists have found other factors proving they have been around longer than dinosaurs.
Rocks from around 505 million years ago have been found with imprints of jellyfish relatives. This study discovered that jellyfish have existed for longer than we may think.
The impressions of the jellyfish on the rocks have traits similar to modern orders of jellyfish—this jellyfish left behind a clear print because its film wasn’t covered in thick sand.
This suggests that modern jellyfish are older than we think or that these ancient jellyfish evolved unusually fast.
What are jellyfish made of?
Jellyfish are comprised of water, gelatin, and multiple layers of skin. These layers include the epidermis, mesoglea, and gastrodermis.
95% of their bodies are water, leaving only 5% of solid matter. This solid matter is the mesoglea, a thick, elastic substance.
As we previously mentioned, they also have a nervous system. They also have a simple digestive cavity that acts as a stomach and intestine and has one opening for both their mouth and anus. This is called an orifice.
The epidermis, the jellyfish’s upper skin, acts as protection for its inner organs. The mesoglea provides oxygen for the jellyfish in low-oxygen areas, and the gastrodermis is the inner layer.
What organs do jellyfish have?
Jellyfish don’t have many organs, but the ones they do have define them jellyfish and make them fascinating creatures. Several small organs called rhopalia influence jellyfish behavior inside a their bell.
They have a statocyst, which senses gravity and allows the jellyfish to move accordingly. They also have ocelli which have light sensitivity and can tell the difference between light and dark.
Their anatomy also consists of cicla, which can sense chemicals around them and nearby currents. They also have balance organs similar to humans, which give them their sense of balance and ability to stay afloat.
All this information is then processed by pacemakers, which control the speed of the jellyfish. It analyses if the jellyfish is in danger and if there is, the jellyfish will speed up and remove itself from the situation.
Tentacles are also considered organs and are an infamous part of a jellyfish. They are the jellyfish’s primary self-defense mechanism and contain multiple stinging cells to attack other organisms.
They are sensitive, and the jellyfish are unaware they are using them to attack. The stinging cells, also known as nematocysts or cnidae, have allowed jellyfish to stay unevolved for millions of years.
They also have oral arms, which drag prey into their mouths. These are attached to the opening of the orifice and can be described as drape-like structures.
In conclusion
Jellyfish do not have brains. Instead, they have a basic set of nerves that perform different bodily functions.
They also do not have a heart. They do not have a circulatory system, as they don’t have any blood to pump around the body.
Lungs are not needed as jellyfish have a different oxygen method. They absorb oxygen through their thin skin and store it to allow them to survive in low-oxygen conditions.
Jellyfish don’t need bones to keep their shape, as the water’s buoyancy decreases the weight of the jellyfish.
They are comprised of water, gelatin, and multiple layers of skin. These layers include the epidermis, mesoglea, and gastrodermis.
Several small organs called rhopalia influence jellyfish behavior inside a jellyfish’s bell. These are considered small organs, alongside the tentacles.
