Are Jellyfish Older Than Dinosaurs? And 7 Other Fascinating Facts

Did you know jellyfish can age backward? Are jellyfish older than dinosaurs? Check out these seemingly immortal invertebrates!

What’s the first animal you think of when you think of the ocean? Chances are it probably isn’t a jellyfish. Many people don’t think about them beyond being careful not to be stung by one in the ocean or watching them gracefully float by in an aquarium.

But did you know that there is a jellyfish that can grow to be the length of a blue whale? Or that the answer to "are jellyfish older than dinosaurs" is an incredible YES! How about that many jellyfish can glow in the dark?

In honor of World Ocean’s Day on June 8th, let's dive into these eight extraordinary facts about jellyfish!

A jellyfish is a very simple animal.

But what exactly is a jellyfish? A jellyfish isn’t a fish but an invertebrate, which means it doesn’t have a backbone. In fact, it doesn’t have much of anything. Jellyfish don’t have a brain, a heart, or even blood, and have a very simple digestive cavity with a single opening for eating and expelling waste. What they do have is water – lots of it. Jellyfish are about 95% water. This makes them highly camouflaged in the ocean. Going a little deeper, the body of the jellyfish is divided into three main parts: the bell, the oral arms (long appendages that move captured prey into their mouths), and the stinging tentacles.

anatomy of a jellyfish

Jellyfish come in a variety of shapes, colors, and sizes.

Though the basic parts of the jellyfish are fixed, the bells, oral arms, and tentacles can be different shapes, sizes, and colors. Thought to be the smallest jellyfish in the world, the Irukandji jellyfish has a bell that only reaches a maximum of 25 millimeters across, about the size of a quarter. A species of box jellyfish, they are one of the most venomous jellyfish in the world despite their tiny size.

The lion’s mane jellyfish (featured in the Sherlock Holmes story “The Adventure of the Lion’s Mane”) is the largest known species of jellyfish by length, reaching up to 120 feet from the top of the bell to the bottom of the tentacles. This is about the length of 4 school buses, making it longer than a blue whale! Nomura's jellyfish are the largest by weight; they can weigh up to 450 pounds. That’s the weight of a piano!

two images: tiny creature in a test tube and a very large one with long tentacles

Are jellyfish older than dinosaurs?

Jellyfish have been around for more than 500 million years. That means they appeared more than 250 million years before the first dinosaurs. However, because jellyfish are soft-bodied and almost all water, jellyfish fossils are incredibly rare. Of those that do exist, the oldest-known jellyfish fossils, found in Utah, date to 505 million years ago and have enough detail to show clear relationships with some modern species of jellyfish.

a close up of a jellyfish

Like butterflies, jellyfish undergo metamorphosis.

Have you ever wondered what a baby jellyfish looks like? What we usually think of as a jellyfish is called a medusa. Medusas lay eggs. Eggs grow into larva called planula – which have been described as looking like furry tic-tacs – and they start swimming until they find somewhere to stick themselves. Once a planula finds a rock, dock, or other place to attach itself to, it stretches into a tube called a polyp. When a polyp is ready, the tube becomes longer and separates out into a series of snowflake-like discs. Each disc will begin to wiggle then pop off the stack. The disc, called an ephyra, is a baby medusa. It pumps its body to swim away. It can grow an inch every few days until it becomes mature medusa. 

There is a species of jellyfish that is basically immortal.

Now that we’ve talked about the jellyfish life cycle, the real fun can begin. Turritopsis dohrnii, a species of tiny jellyfish discovered in the Mediterranean Sea, can turn from medusas into polyps when damaged or starving. This would be like a butterfly turning back into a caterpillar or a frog turning back into a tadpole. T. dohrnii can go back and forth between its polyp and medusa stages, leading to it being known as “the immortal jellyfish.” Further research shows that other species of jellyfish may be able to reserve-age, too. Studying the cells of these jellyfish has potential uses for medicine.

a clear jellyfish with a bright red center

Some jellyfish get sleepy.

Since they lack a brain, jellyfish have a very different kind of nervous system from many animals. Jellyfish have what are called “nerve nets,” which are loose networks of neurons and sensors spread out across their bodies. Even with this very simple nervous system, jellyfish can carry out a variety of behaviors, including some once thought impossible. A 2017 study showed that one type of jellyfish (Cassiopea, or the upside-down jellyfish) enters a sleep-like state at night and were sluggish when they didn’t get a full night of sleep. This was the first time an animal without a brain was observed sleeping!

a cluster of jellyfish sleeping

Glow-in-the-dark jellyfish revolutionized biotechnology.

Bioluminescence is the ability of living things to make light through chemical processes. The jellyfish species Aequorea victoria, also known as the crystal jelly, glows bright green due to both bioluminescent and fluorescent proteins. The green fluorescent protein (GFP), which glows green under blue light, has since been cloned and inserted into other organisms’ genetic codes, allowing scientists to literally see how genes and cells work. According to Juli Berwald, scientists have used fluorescent proteins made from GFP to see how bacteria divide; how cancer, Alzheimer’s and HIV affect cells; to trace neurological pathways in the brain; to test for diseases like malaria and ebola; to build solar cells, and to make low-temperature, energy-efficient lasers.

bright green glow in the dark jellyfish

Scientists are making robo-jellyfish.

Scientists and engineers have created robotic jellyfish to assist them in studying the ocean. In 2018, Erik Engeberg, an associate professor of engineering at Florida Atlantic University, and his team tested prototypes of a soft-bodied robot that moves like a jellyfish. The robot can monitor and study the underwater environments of coral reefs without harming them, since these robo-jellyfish are quieter and safer for marine life than underwater drones. Dr. Edie Widder developed an electronic jellyfish as a lure to attract large, deep-sea predators. Her e-jelly, which used the bioluminescent patterns of the jellyfish Atolla wyvillei, was used to capture the first video footage of a living giant squid in 2012.

Expand on the activity! 

Want more jellyfish?

Check out these jellyfish live cameras from the Georgia Aquarium and Monterey Bay Aquarium!

Are Lionfish Safe to Eat? How You Can Help Advance Ocean Conservation

Are lionfish safe to eat? If they are, why should we have lionfish for lunch?

Deadly. Beautiful. Devastating. While lionfish may be stunning to look at, this invasive species has been wreaking havoc among marine ecosystems such as coral reefs along Florida coasts since the 1990s. In Florida waters, lionfish have no predators and have been eating many native species of fish, causing great ecological damage, with some areas showing an 85-90% decrease in their native fish.

 

The good news is you can help by having a snack! You probably won't see them on the menu at many seafood restaurants, so you may be wondering "Are lionfish safe to eat?" The answer is yes! 

Lionfish spines are venomous, not poisonous. Meaning, once the spines are removed, the rest of the fish is completely edible – and quite delicious. Not only does eating lionfish help remove these pesky fish from Florida’s waters, but it also offers a sustainable fishing alternative.

 

By including lionfish in your diet, you’re promoting sustainable fishing which is a great way to help advance ocean conservation. Growing demand for seafood has led to fishing practices that are depleting populations of fish and other aquatic creatures. Together, we can make a difference by purchasing seafood from responsible, sustainable fisheries and by creating demand for lionfish by purchasing it directly from reputable sources.

 

This information was sourced from National Geographic and NOAA Fisheries

How to be a Conservation Hero! 

Did you know oceans cover 71 percent of the Earth's surface and contain 97 percent of the Earth's water? Although many of us, especially in Florida, think of the oceans as a place to relax and soak up the sun – they are also vital to life on Earth and home to an estimated one million species. It is our duty to help conserve and protect our oceans, and the marine life that inhabit them.

 

There are many ways you can help protect the oceans and marine life. Check out these six ways you can practice ocean-friendly habits and help save our oceans. 

World Oceans Day

Calling all ocean lovers! You’re invited to dive into Orlando Science Center’s World Oceans Day celebration presented by SeaWorld Parks & Resorts Orlando.

Community partners will educate guests on ocean conservation and inspire them to create a better future. Look forward to special ocean programming throughout the building during the event and learn how we can protect and nurture our shared ocean!

Six Ways to Practice Ocean Conservation

Celebrate World Oceans Day on June 8!

Did you know oceans cover 71 percent of the Earth's surface and contain 97 percent of the Earth's water? Although many of us, especially in Florida, think of the oceans as a place to relax and soak up the sun – they are also vital to life on Earth and home to an estimated one million species. It is our duty to help conserve and protect our oceans, and the marine life that inhabit them.

In celebration of World Oceans Day on June 8, we've compiled the top six ways you can practice ocean-friendly habits and help protect our oceans. Be sure to dive into Orlando Science Center on June 8 for our World Oceans Day celebration to learn about ocean and marine ecosystem conservation initiatives to protect and nurture our shared ocean, take part in hands-on special marine-themed programming during the event, catch a film in our Digital Adventure Theater focused on ocean and marine life, and much more!

Here are Six Ways You Can Practice Ocean Conservation

  1. Use Less Plastic – Plastics that end up in the oceans, pollute and kill tens of thousands of marine animals every year. While single-use plastics create unnecessary waste, sustainable alternatives do exist. Instead of using plastic bags at the grocery store, bring a few tote bags to haul your goods. Using reusable water bottles, straws, and utensils are also great ways to reduce your plastic consumption.
  2. Beach Cleanup – Help keep our oceans clean by volunteering for a beach cleanup. Picking up litter is an effective way to reduce pollution, beautify your area and make new friends along the way!
  3. Enjoy the Water Responsibly – While boating, kayaking, and other recreational activities are a ton of fun, it’s essential to remember that you are in another creature’s habitat. To protect marine life, be sure to avoid throwing anything overboard.
  4. Volunteer Your Time– Consider volunteering your time to an organization or charity that is working to protect our oceans and marine wildlife. Join a local group to participate in projects and fundraisers that advance conservation efforts.
  5. Think Before You Flush – Medicines and other materials often flushed down the toilet have a damaging effect on water quality and marine life. Not only do these substances harm our oceans, but they also pollute local waterways and soil. Examples of harmful products include floss, cat litter, insecticides and more.
  6. Take Note of Your Carbon Footprint –  Carbon dioxide can cause acidification of the water, which impacts the health of marine life. Learn more about how you can tweak your energy habits for a more sustainable lifestyle. Driving less and using fewer single-use goods are great ways to start.

This information was sourced from National Geographic and The Oceanic Institute.