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Jellyfish Facts

Jellyfish have been on the earth for millions of years, far longer than the dinosaurs.

There are many different types of jellyfish in all the oceans; some are harmless, and some are very dangerous.

Jellyfish Facts for Kids

  • More than 2,000 different types of jellyfish exist worldwide
  • Jellyfish are invertebrates, not fish.
  • Some Jellyfish can grow up to 6.6 feet long 
  • They eat fish, shrimp, crabs, and small plants
  • Prey is stunned or paralyzed by their tentacles.

Types of Jellyfish

Lion’s Mane Jellyfish (Cyanea capillata)

Lion’s mane jellyfish are one of the biggest known jellyfish species, with a diameter of 210 centimeters (7 feet) and a tentacle length of 36.6 m (120 feet). There’s a lot of it in the English Channel, Irish Sea, North Sea, and western Scandinavian waters.

Lion’s mane jellyfish are named for their showy, trailing tentacles reminiscent of a lion’s mane. They can reach a diameter of over 2 m (6 ft 7 in) in the far northern latitudes.

Lion’s mane jellyfish are found near the surface and depend on ocean currents to travel great distances.

Upside-Down Jellyfish (Cassiopea sp.)

Cassiopea is a genus of true jellyfish are found in warmer coastal regions worldwide. They live upside-down on the bottom and partake in a symbiotic relationship with photosynthetic dinoflagellates.

Cassiopea species have a mild sting, but sensitive individuals may have a stronger reaction. The stings appear as red rash-like skin irritation and are known for being extraordinarily itchy.

Moon Jellyfish (Aurelia aurita)

The common jellyfish, Aurelia aurita, is a species of the genus Aurelia. It is difficult to identify Aurelia medusae without genetic sampling, but most of this article applies equally to all species of the genus Aurelia.

Facts for Kids
Facts for Kids

The jellyfish is almost entirely translucent, has four horseshoe-shaped gonads, and drifts with the current.

They feed on plankton that includes mollusks, crustaceans, tunicate larvae, rotifers, young polychaetes, protozoans, diatoms, eggs, fish eggs, and other small organisms. They use nematocysts to capture prey and also protect themselves from predators.

Nomura Jellyfish (Nemopilema nomurai)

Nomura’s jellyfish can grow up to 2 m (6 ft 7 in) in diameter and weigh up to 200 kg (440 lb). They are found in the waters between China and Japan and may be affected by climate change, overfishing, and coastal modification.

Nemopilema nomurai is a species of rhizostome that is found in the Yellow Sea. In June and July, it expatriates larval stage jellyfish via the Tsushima strait.

Deep Red Jellyfish (Crossota norvegica)

Crossota norvegica is a species of hydrozoan found in the Arctic Ocean at depths below 1,000 m (3,300 ft). It is known for its vibrant red hue.

Crossota norvegica is unique among cnidarians because it does not develop into a polyp, and instead lives its entire life in the planktonic stage or the planula stage. It is also unclear whether or not this species is dioecius, or a sequential hermaphrodite.

What is a Jellyfish?

A jellyfish is an animal that lives in water. It does not have any legs. Its body comprises two parts; its bell, which looks like a flower, and its tentacles. The tentacles are used for feeding and catching food. They also help the jellyfish move around.

The tentacles are very long and thin. They stretch out from the bottom of the jellyfish’s body, and they come together at the top. This makes them look like a big fans.

Jellyfish do not have eyes but use other senses such as touch and taste to see what is happening around them. Their skin is covered by tiny hairs called cilia. These cilia allow the jellyfish to swim quickly.

A jellyfish can change color. When it wants to hide, it changes into a transparent form. This allows it to blend in with the background.

Jellyfish live in all oceans. However, there are different types of jellyfish. Some jellyfish are poisonous, while others are edible.

What is a bloom?

A jellyfish bloom occurs when there are many jellyfish in one area. These blooms can occur naturally, but human activities such as pollution, overfishing, climate change, and ocean warming contribute to jellyfish blooms.

In some places, jellyfish blooms happen every year. But in other parts of the world, jellyfish blooms are rare. Scientists don’t know why jellyfish blooms happen in certain locations, but they think environmental conditions play a role. Some blooms are seasonal, while others seem to occur throughout the year.

How do jellyfish blooms form?

Jellyfish blooms occur when warm surface waters mix with cold deep water. This creates conditions that favor the growth of microscopic plants called phytoplankton, which produces oxygen.

When the bloom reaches a certain size, it becomes buoyant enough to float out of the depths and settle onto the sea floor. As the jellyfish move around on the bottom, they stir up sand and gravel, creating a thick layer of sediment that traps additional nutrients.

At some point, the bloom begins to break down into smaller pieces, forming what looks like a giant blob of gelatinous goop.

How long do jellyfish live?

The average lifespan of a jellyfish varies depending on the type of animal. For example, a single specimen of the Portuguese man o’ war can live for 1 year. 

Why do some jellyfish sting?

Jellyfish have tiny stinging cells in their tentacle tips called nematocysts, which help them catch prey. Jellyfish use these nematocysts to inject toxins into their prey. A person stung by these creatures feels pain because the toxin travels directly through the victim’s skin.

The Portuguese Man O’ War is the most common jellyfish that causes painful stings.

What do Jellyfish Eat?

Jellyfish eat crab, fish, shrimp, and small plants. They also eat plankton which makes up about 80% of their diet.

What is a baby jellyfish called?

Baby jellyfish are called ephyra.

How do jellyfish reproduce

Jellyfish are hermaphrodites. They have both male and female reproductive organs. The eggs develop inside the body of the mother jellyfish. When they hatch, the larvae swim away from the parent jellyfish.

What do jellyfish do?

According to new research, jellyfish are much more beneficial to marine life than previously thought. To reduce survivorship and recruitment, they compete for food with adult fish or prey on eggs and larvae.

How many years can a jellyfish live?

Jellyfish are not known for living long lives. They usually die within 1 – 3 years after they hatch from an egg. However, there have been reports of jellyfish that lived as long as six years.

How do jellyfish breed

As jellyfish grow, they take on two different body forms: medusas and polyps. Medusae reproduce sexually by spawning eggs and sperm, while polyps can reproduce asexually by budding.

How long have jellyfish been around

Jellyfish are an ancient group of marine animals that first appeared during the Cambrian period (about 500 million years ago). They are related to other invertebrates such as molluscs and arthropods.

Jellyfishes are eumetazoa, meaning they have both animal and plant characteristics. Their bodies consist of two layers; a gelatinous outer layer called mesoglea, which contains water and nutrients, and an inner cell-like structure called gastrodermis, which contains digestive enzymes.

The jellyfish body plan was established by studying the anatomy of the medusa stage, which consists of a bell-shaped umbrella made from thousands of tiny polyps. These polyps secrete a substance called coelenteron, which forms the main part of the jellyfish body. This substance is responsible for giving the jellyfish its characteristic transparency.

The tentacles of the jellyfish are used for capturing prey and defense. Tentacles contain nematocysts, which are stinging cells that fire when stimulated by touch. Nematocysts are found on all parts of the tentacle except at the base, where there are specialized structures known as cirri.

Tentacles may also function as sensory organs. In addition, many species use them to communicate. For example, the moon jellies, *Aurelia aurita* and *Chrysaora quinquecirrha*, produce light flashes using their tentacles to attract mates.

How many eyes do jellyfish have

There are different species of jellyfish across the world. Some species have one eye. There are even some jellyfish that have no eyes at all. They have complex eyes that detect light signals in the environment.

Their light-sensing organ is at the bottom of their bell disks and is located within a formation known as rhopalia.

What do you call a group of jellyfish

A group of jellyfish is called a SMACK

How many eggs do jellyfish lay

Some jellyfish can lay up to 45,000 eggs in one go.

What are jellyfish good for

Fish and sea turtles rely on them for food. Jellyfish play an important role in the marine ecosystem.

How do jellyfish obtain food?

Stinging cells in their tentacles capture small organisms like plankton or fish larvae. The tentacles then transport these captured items into the mouth.

How many offspring do jellyfish have

They can lay up to 45,000 jellyfish eggs in one go.

Are jellyfish increasing globally?

With the warming sea, we see more jellyfish blooms. Their increase is due to climate change.

Why do some jellyfish sting?

Jellyfish are not stinging for fun. They have evolved over millions of years to protect themselves from predators. Their stings are designed to paralyze prey and make them easier to eat.

Jellyfish use their stings as a last resort when they feel threatened by other animals.

They release toxins into the water, which cause pain and paralysis. The toxin is released slowly over time and effectively kills large fish.

The venomous cells are located on the tentacles of the jellyfish when an animal comes close enough, the tentacle contracts and squirts the venom directly into its victim.

How common are jellyfish stings?

Jellyfish stings are rare, but they do happen. The most dangerous type of jellyfish sting is called box jellyfish. It’s not uncommon for people who have been stung by this kind of jellyfish to need medical treatment.

The symptoms of a jellyfish sting include pain, redness, swelling, blisters, and itching. If you think you may have been stung by a jellyfish, then seek immediate medical help.

How many hearts do jellyfish have

As well as having no heart, bones, or blood, they are made up of about 95% water.

What is unique about jellyfish

Jellyfish are not just animals. They are also plants. They have tentacles that help them move around and capture prey.

Jellyfish tentacles trap food and then filter it from the water. Jellyfish do not have brains, but they do have nerve cells called cilia. These cilia allow jellyfish to sense light changes and movement.

How old is the oldest jellyfish

Turritopsis dohrnii, dubbed ‘the immortal jellyfish,’ the adult medusa returns to its polyp form, regenerating its cells and creating new, youthful cells. So basically, they can live forever.

Does a jellyfish have blood?

 No, jellyfish don’t have blood, brains, or hearts.

Can jellyfish feel pain?

Jellyfish don’t feel pain because they lack nerves. They have no brain, heart, bones, or respiratory system.

Do jellyfish have brains

No, they don’t have a brain

Do jellyfish glow in the dark

In the dark, jellyfish glow in green, blue, and purple colors. Through bioluminescence, they produce light. As sunlight cannot reach the deep ocean, deep sea animals are prone to this process.

More Facts for Kids

  • Jellyfish is a name given to sea creatures that seem made up of a gelatinous substance. They are made up of protein and water.
  • Some jellyfish can grow as large as a human being, while others are as tiny as the head of a pin.
  • People in some countries consider jellyfish a type of food.
  • Jellyfish do not have any brains, but some types do have eyes.
  • Jellyfish that sting is called ‘medusae.’
  • Jellyfish that group together are referred to as a ‘smack.’
  • Jellyfish cannot swim but must drift along with the oceans’ tides. When a large number of jellyfish end up in the same area due to the tides, it is called a ‘bloom.’
  • Each of the jellyfish species has a different lifecycle. Some can live for just a few days, while others can live as long as a year.
  • Jellyfish reproduce with both male and female and create the tiny ‘planulae’ that falls to the ocean bottom. Each of the ‘planulae’ will form polyps, creating small buds that end up being the baby jellyfish, called ‘ephyrae.’
  • Jellyfish that sting has long tentacles with stinging cells at the ends. They are designed for capturing their food and injecting toxins to allow them to eat.