All About The Life Cycle of a Jellyfish

We have a special fondness in our family when it comes to talking about Jellyfish. My Great Grandpa was Professor Lemuel A Fraser from the University of Wisconsin’s Zoology department. While I was very little when he passed, he was a dear man that my mom still talks about fondly.

His life’s research was all about Jellyfish – and he discovered some pretty cool things back in the years he spent summers out on the coast doing his research. I could go on and on about him – but you dig into his marine research on your own if you are interested.

There are many life cycles in the animal kingdom, but few are as unique and interesting as that of jellyfish. The jellyfish life cycle is a fascinating process that starts when eggs hatch into larvae, continue through becoming polyps (stages between larva and adult), they develop into free-swimming medusae which reproduce sexually to produce more jellyfish. The life cycle of a jellyfish is both interesting and full of surprises!

The Life Cycle of a Jellyfish

When looking at the life cycle of a jellyfish, you see that throughout its life it takes on two different body forms: Medusa and Polyps. These two different types of body forms have different functions and abilities. When you look at the polyp form, they are only able to reproduce asexually versus the medusa form where they can reproduce sexually with an egg and sperm. 

What is a Jellyfish?

Jellyfish are those gelatinous-looking blobs in the water with their tentacles dragging behind. They are invertebrates which means they do not have a backbone. They are considered part of the artificial category for species. They are quite literally “Jellies”, with no backbone, no brain or heart. They are made up of a gelatin-like substance. Their bodies consist mostly of water and 95% of jellyfish weigh less than one ounce. 

Jellyfish don’t have any natural predators, this is because their tentacles (stingers) are covered by an outer layer of skin called cnidocytes. Cnidocyte is a protective layer on the tentacles of jellyfish that explode cnidocytes.

These are tiny microscopic needles that are used as an injecting system for the jellyfish venom. If a predator tries to come along and harm the jellyfish, those cnidocytes are used as a defensive mechanism to sting their predator. 

Are Jellyfish living creatures?

Yes, they are invertebrates which are a type of plankton. They can still sense light and use their tentacles to swim about in the ocean. Their sense of light stems from their nervous system, which also allows them to sense temperature and touch. They are a bundle of nerves! 

What is the Life Cycle of a Jellyfish?

The lifespan of a jellyfish ranges from 6 months to two years and throughout their life they go through 6 different stages. 

The first stage is the egg stage, once the medusa fertilizes the eggs they release them and the egg develops into planula larvae. These larvae then float about until they reach the ocean floor and settle in. Once they are settled into the seafloor they move into the second phase.

The polyp phase is the next phase that happens once the larvae have settled into the ocean floor. They grow into polyps and feed until the springtime. Once spring rolls around they start to mature into the third stage. 

This is where the polyps start to develop buds, these buds become unattached from the polyp and form immature jellyfish called Ephyra Larva. This larva then matures into jellyfish, known as the fourth stage. From the fourth stage, they need to go into the fifth stage of metamorphosis. 

This metamorphosis stage changed the jellyfish into a medusa (jellyfish with tentacles) that can reproduce sexually. Lastly, after going through a metamorphosis, they enter their last stage of becoming a medusa, reproducing and then dying off into an egg or sperm again to repeat the cycle. 

What To Do If Stung By A Jellyfish

If you happen to get stung by a jellyfish try not to panic! Thrashing around the water will only increase the stress of the jellyfish and the number of stings you will receive. The next thing you need to do is to notify someone immediately who can help you get out of the water. If you are stung by a rare and toxic jellyfish, drowning is possible, so get to the beach or on a boat as soon as possible.

Once you notify someone, you need to seek a doctor’s assistance as soon as possible! Most people won’t even know what happened to them and won’t know how to properly take care of the wound. Only trained medical professionals can properly evaluate the severity of the stings and the appropriate treatment for you. 

Most of the time individuals will not seek medical help. Instead, they rely on home remedies for jellyfish stings seen on television or told to them by locals. It is a mystery why sting victims don’t seek immediate medical assistance. This isn’t a safe option and can turn fatal very quickly. Even if it is a general sting, and home remedies would work fine, seek medical help because again you never know if it is a general sting or a severe sting. 

If you were bitten by a snake, would you wait and see what happens? Of course not – you would go to the emergency room as fast as possible! Stings or bites from any sea creature, including jellyfish, sea urchins, rays, and others, should be considered the same as a snake bite and treated accordingly.

Most jellyfish sting home remedies usually involve the application of human urine, a solution of meat tenderizer, or fresh water to the site of the stings. Many of these home remedies listed are wrong and will actually make the situation worse.

Why Most Home Remedies For Jellyfish Stings Are Wrong

Jellyfish are evolved in the ocean, which means their stinging defenses are optimized for use in saltwater. The use of freshwater will increase the venom injection of any stingers still stuck in the victim! Likewise, massaging the sting area, or using alcohol, spirits, ammonia, or urine will also encourage the release of venom.

The mythical urine cure is probably the most misunderstood, yet is likely the most well-known. It was popularized on the television comedy “Friends” in the episode “The One With the Jellyfish.”

Let’s face it – would you want someone to pee on YOUR leg? Just eww..

How To Deactivate Jellyfish Sting Venom

If you can’t get to a doctor, the first step in properly treating jellyfish stings is to deactivate the stinging cells still stuck in the victim. The following deactivation solutions may be used:

* A 5% percent acetic acid solution (available commercially as white vinegar) is the preferred method.

* Solutions of a meat tenderizer or sodium bicarbonate (baking soda) will neutralize any stingers that have not yet released their poison. Meat tenderizer should not be left on the skin for more than 15 minutes.

* None of these substances should be used in the eyes. In the case of stings on or near the eyes, dip a towel in the deactivating solution and dab it around the eyes, but not directly into open eyes.

* Saltwater can be used if none of the above products are available.

Removing Jellyfish Stingers

After the stingers are deactivated, persons with protective clothes and gloves should carefully remove any tentacles from the victim.

Any remaining embedded stingers should then be removed. This can be done by applying shaving cream to the affected area. Carefully scrape the sting area with a sharp surface, such as a razor, a knife blade, or even a sharp plastic edge such as a credit card.

Mild skin irritation can be soothed with the use of over-the-counter antihistamines containing diphenhydramine (such as Benadryl).

These Treatments Are Not Substitutes For A Doctor

Always see a doctor if you are stung or bitten by a jellyfish or any other sea creature. These jellyfish sting home remedies are not meant to replace a doctor’s expertise. You may wish to begin applying the proper care as first aid while waiting for the ambulance. If you do, tell the paramedics and doctor what steps you have taken.

But whatever you do, please don’t urinate on your jellyfish-stung friend. Although it makes for a funny story later, it will make your friend’s pain – and humiliation – worse.

Now – get our The Life Cycle of a Jellyfish Activity Set!

See it in our store HERE: Jellyfish Printable Activity, Jellyfish, Digital Download, Instant Download, Printable Download, STEM, STEM Worksheets, STEM Workbook

Check out a few other great life cycle articles I shared:

• The Lifecycle of a Star: A Walk Through the Life Cycles
• The Life Cycle of a Butterfly: How They Grow and Change
• FREE Cow Life Cycle Learning Poster
• From Egg to Adult: The Praying Mantis Lifecycle
• How to Make a Snake Life Cycle Lapbook
• The Lifecycle of a Frog: A Look at the Baby, Tadpole, and Adult
• The Incredible Life Cycle of a Fly: From Egg to Death
• A Brief Look at the Life Cycle of a Beetle Worksheet
• The Life Cycle of a Great White Shark: Survival in the Ocean
• The Lifecycle of a Ladybug: The Life and Times