Lion's mane jellyfish
Cyanea capillata 36.5 m record lengthThe largest known jellyfish species. The biggest specimen on record stretched about 120 feet from bell to tentacle tips.[5]
Ocean Science Quiz · 15 Questions · 3 Depth Zones
Bing Jellyfish Quiz – Test Your Ocean Knowledge
Jellyfish have drifted through Earth's seas for more than half a billion years without a brain, a heart or a single bone. Dive from the sunlit surface to the midnight zone and find out how much you really know about these strange, beautiful animals.
0 m · Briefing
How the Dive Works
This isn't a flat list of trivia. The quiz is a descent: every question takes you deeper, and the questions get harder as the light fades.
ZONE 01 · 0–200 m
Sunlight Zone
Five warm-up questions on what jellyfish are and how they're built.
ZONE 02 · 200–1,000 m
Twilight Zone
Five questions on life cycles, senses and surprising behavior.
ZONE 03 · 1,000 m +
Midnight Zone
Five tough questions on records, fossils, science and safety.
Pick an answer and you'll instantly see whether you were right, plus a short field note explaining why, with the source it came from. There's no timer, so take your time and read the notes. That's where most of the learning happens. When you surface, you'll receive a dive rank. If you enjoy this format, you can also Play Bing News Quiz for a daily round of headline questions.
50 m · Descent begins
The Jellyfish Quiz
15 questions · instant explanations · no sign-up needed
ZoneSunlight
Depth0 m
Question1 / 15
Correct0
Question 01
Loading quiz…
200 m · Field basics
What Exactly Is a Jellyfish?
The name is misleading on both counts: a jellyfish is neither jelly nor fish.
Jellyfish are invertebrates in the phylum Cnidaria, an ancient group they share with corals and sea anemones.[4] NOAA's ocean explorers point out that, whatever the common name suggests, jellyfish are not fish at all, and they don't have a brain.[1] What they do have is a soft, bell-shaped body that is roughly 95% water, which is why their fossils are so rare and so prized.[4]
Instead of a centralized brain, jellyfish rely on a diffuse network of nerves spread through the body. Despite that simple wiring, NOAA notes they can sense light and coordinate their swimming, which helps them stay where food is plentiful.[3] Their tentacles are armed with nematocysts, microscopic stinging capsules that fire when triggered and inject venom into prey.[13]
Four main jellyfish groups
Biologists use "jellyfish" loosely, but the medusa-producing cnidarians fall into a few familiar groups: true jellyfish (Scyphozoa, like the moon jelly), box jellyfish (Cubozoa), stalked jellyfish (Staurozoa) and many small hydrozoan medusae.[4] Each group has its own body plan, and some are far more dangerous to humans than others.
No brain, no heart, no bones, yet jellyfish were already efficient swimming predators in the Cambrian seas.
That last point isn't poetic license. In 2023, the Royal Ontario Museum described Burgessomedusa phasmiformis, a bell-shaped swimming jellyfish preserved in the 505-million-year-old Burgess Shale of the Canadian Rockies. It is the oldest swimming jellyfish yet identified in the fossil record.[4]
400 m · Biology
The Jellyfish Life Cycle
The floating, bell-shaped animal most people picture is only one chapter of a jellyfish's life.
Many true jellyfish alternate between a tiny, stationary polyp fixed to the seafloor and the free-swimming medusa. Here's the typical route for a scyphozoan such as the moon jelly:
Egg & sperm
Adult medusae release gametes; fertilization produces an embryo.
Planula
A tiny ciliated larva swims briefly, then settles on a hard surface.
Polyp
A stalk-like form anchored to the seafloor; it can clone itself by budding.
Ephyra
The polyp splits into stacked discs that break free as baby jellies.
Medusa
The familiar adult: pulsing bell, trailing tentacles, ready to breed.
This two-phase life explains why jellyfish can appear suddenly in huge numbers. A single patch of polyps can release many young jellies when conditions are right, and the resulting "blooms" can crowd coastal waters. NOAA explorers note that blooming jellies such as Cyanea are also an important meal for leatherback sea turtles.[2]
700 m · Specimen gallery
Five Record-Breaking Jellies
Several quiz questions draw on these five species. Study them before you dive again.
Box jellyfish
Class Cubozoa 24 eyesFour sensory clubs called rhopalia carry six eyes each, including lens eyes that work a bit like ours.[7] Some tropical species can be deadly.[12]
"Immortal" jellyfish
Turritopsis dohrnii 4.5 mm adult sizeWhen injured or starved, it can turn back into a polyp through transdifferentiation, essentially rewinding its life cycle.[6]
Upside-down jellyfish
Cassiopea 2017 sleep discoveryCaltech researchers found that this bottom-resting jelly shows the hallmarks of sleep, making it the first known sleeper without a centralized nervous system.[8]
Crystal jelly
Aequorea victoria 2008 Nobel Prize in ChemistryGreen fluorescent protein (GFP), first found in this jelly, became a glowing tag used in labs worldwide and earned a Nobel Prize.[9]
A note on "immortal": Turritopsis dohrnii isn't invincible. In the wild, most are eaten or die of disease long before they can reset. What makes it remarkable is its ability to reverse development at all, a trait that interests scientists who study regeneration and aging.[6]
1,000 m · Identity check
Jellyfish Look-Alikes
Not everything that drifts and wobbles is a jellyfish. Two famous look-alikes trip up quiz takers every time.
The real thing
True jellyfish
- A single animal (one individual)
- Phylum Cnidaria, with stinging nematocysts
- Many have polyp and medusa stages
- Example: moon jelly, lion's mane
Look-alike #1
Portuguese man o' war
- A siphonophore: a colony of specialized organisms working as one[10]
- Floats with a gas-filled sail at the surface
- Powerful sting despite not being a jellyfish
- Related "bluebottles" occur in Australia
Look-alike #2
Comb jellies
- Phylum Ctenophora, not true jellyfish[11]
- Swim with rows of beating, hair-like cilia
- Cilia often scatter light into rainbow shimmers
- Example: the sea walnut
Why does the distinction matter beyond trivia? First aid differs. Australia's official health service advises vinegar for tropical box jellyfish stings but specifically not for bluebottle stings, where hot water is used instead.[12]
1,500 m · Human connections
Jellyfish and People
They lit up modern biology
When researchers learned to borrow the gene for green fluorescent protein from the crystal jelly, they gained a way to make cells, proteins and even whole organisms glow under the microscope. Osamu Shimomura, Martin Chalfie and Roger Y. Tsien shared the 2008 Nobel Prize in Chemistry for the discovery and development of GFP.[9] Today it's a routine tool for watching living processes in real time.
They are food, for many
Jellyfish sit in the middle of ocean food webs. NOAA lists tunas, sharks, turtles and humans among the animals that eat them,[1] and prepared jellyfish is a familiar ingredient in parts of East and Southeast Asia.
They don't chase swimmers
A common fear is that jellyfish "go after" people. NOAA calls this a myth: any contact is accidental, since jellyfish mostly drift with currents while hunting small prey.[3] NOAA scientists have even tested ways to forecast jellyfish in Chesapeake Bay using water temperature and salinity so beachgoers know when encounters are more likely.[3]
2,000 m · Practical knowledge
Sting Safety Essentials
Most jellyfish stings cause short-lived pain, redness and itching, but a few species can cause serious illness.[13] The right first aid depends on where you are and what stung you, which is why advice varies between countries.
⚠ General first-aid principles
- Get out of the water calmly and call for help if symptoms are severe (trouble breathing, chest pain, confusion).
- Rinse with seawater, not fresh water. Fresh water can trigger more stinging cells to fire.[12][13]
- Remove tentacles carefully with tweezers or a gloved hand; don't rub the area.[13]
- Tropical box jellyfish areas: Australian health authorities advise pouring vinegar on the sting after removing tentacles and getting to hospital.[12]
- Bluebottle and most other stings: immerse in hot water (about 45 °C, not scalding) for 20 minutes to ease pain, and skip the vinegar.[12]
- Skip the myths. Urine, rubbing with sand and alcohol are not recommended remedies.
This section is general educational information, not medical advice. Always follow local lifeguard instructions and seek professional medical care for serious stings or allergic reactions.
3,000 m · Questions from the surface
Frequently Asked Questions
Are jellyfish fish?
No. Jellyfish are invertebrates in the phylum Cnidaria, related to corals and sea anemones. They have no backbone, no gills and no brain, so they aren't fish despite the name.
How do jellyfish survive without a brain?
They use a decentralized nerve net plus sensory structures (rhopalia) around the bell that detect light, gravity and touch. That's enough to coordinate swimming, feeding and, in box jellyfish, surprisingly sophisticated navigation.
Can a jellyfish really live forever?
Turritopsis dohrnii can revert from adult medusa to polyp when stressed, which in theory lets it restart its life cycle repeatedly. In practice, predators and disease kill most individuals, so "biologically immortal" describes a capability, not a guarantee.
What is the biggest jellyfish in the world?
The lion's mane jellyfish (Cyanea capillata) is the largest known species. The longest specimen on record measured about 36.5 meters (120 feet) from bell to tentacle tips, according to the Smithsonian.
Should you pee on a jellyfish sting?
No. Urine is not a recommended treatment and may make things worse. Rinse with seawater, remove tentacles carefully, and follow local first-aid guidance: vinegar for tropical box jellyfish, hot water for many other stings.
Is this quiz affiliated with Microsoft Bing?
No. This is an independent educational quiz inspired by the Bing-style daily quiz format. It is not created, sponsored or endorsed by Microsoft, and playing it does not earn Microsoft Rewards points.
📋 Answer Key: all 15 questions tap to reveal (spoilers!)
- Jellyfish belong to: Cnidarians
- Body water content: About 95%
- Jellyfish lack: A brain
- A group of jellyfish: A smack
- Stinging capsules: Nematocysts
- Stage fixed to the seafloor: Polyp
- Box jellyfish eyes: 24
- The "immortal" jellyfish: Turritopsis dohrnii
- Cassiopea showed signs of: Sleep
- Jellyfish-eating reptile: Leatherback sea turtle
- Largest known jellyfish: Lion's mane
- Oldest swimming jellyfish fossil: About 505 million years
- Source of GFP: Crystal jelly (Aequorea victoria)
- Portuguese man o' war is a: Siphonophore colony
- Box jellyfish sting (tropical Australia): Vinegar
Resurface · Keep playing
Ready for Your Next Dive?
Daily quizzes are a simple, low-pressure way to keep learning. Try one of these next:
4,000 m · The abyss
Sources & Fact-Checking
Every quiz answer and article claim above was checked against the following scientific, government and museum sources. Bracketed numbers in the text link to this list.
- NOAA Ocean Exploration. "Happy World Jellyfish Day" (2019 Southeastern U.S. expedition log).
- NOAA Ocean Exploration. "Blooming Jellyfish", Windows to the Deep 2018.
- NOAA. "Fact vs. fiction: 3 things you thought you knew about jellyfish."
- Royal Ontario Museum via ScienceDaily. "Oldest known species of swimming jellyfish identified" (Aug. 2023).
- Smithsonian Ocean. "Extreme Jellyfish."
- American Museum of Natural History. "The Immortal Jellyfish."
- Petie, R., Garm, A. & Nilsson, D.-E. "Visual control of steering in the box jellyfish Tripedalia cystophora," Journal of Experimental Biology (2011).
- Caltech. "The Surprising, Ancient Behavior of Jellyfish" (Sept. 2017), on Nath et al., Current Biology.
- NobelPrize.org. "The Nobel Prize in Chemistry 2008."
- NOAA National Ocean Service. "What is a Portuguese man o' war?"
- Delaware DNREC. "Jellyfish to Watch Out For."
- healthdirect Australia (Australian Government). "Jellyfish stings."
- Cleveland Clinic. "Jellyfish Sting: Symptoms & Treatment."
How this quiz was made: Questions were written from scratch for this page, then each answer was verified against at least one primary scientific, government or museum source listed above. Where sources disagree on a figure (for example, record jellyfish lengths), we use the figure given by the most authoritative institution and say so. Spotted an error? Please let us know through the site's contact page and we'll review and correct it promptly.
This is an independent educational quiz. It is not affiliated with, sponsored by, or endorsed by Microsoft Corporation or Bing. "Bing" is a trademark of Microsoft Corporation and is used here only to describe the quiz format. Sting-safety content is for general information and is not a substitute for professional medical advice.