Jellyfish Quiz: Brainless Drifters of the Ocean

This jellyfish quiz dives into the lives of the ocean's oldest drifters, from cnidarians without brains to the deadly box jellyfish, the giant lion's mane, stinging cells, a smack of jellyfish, a Nobel Prize-winning glowing protein, the Portuguese man o' war and hungry leatherback turtles.

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🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 90 Seconds

Question 1 / 10 Time: 90s

Bodies
Which of these do jellyfish NOT have?
Classification
Jellyfish belong to which group of animals?
Danger
Which jellyfish is considered one of the most venomous animals in the world?
Records
Which jellyfish is one of the largest, with tentacles that can stretch more than 30 meters?
History
Roughly how long have jellyfish existed on Earth?
Words
What is one name for a group of jellyfish?
Stings
What are the tiny stinging cells of jellyfish called?
Science
A glowing protein first found in the crystal jelly won scientists a 2008 Nobel Prize in which field?
Look-Alikes
What is the Portuguese man o' war, often mistaken for a jellyfish?
Predators
Which sea turtle feeds mainly on jellyfish?

Explanations: answer key for all 10 questions

Q1: Which of these do jellyfish NOT have?
Answer: Brain
Jellyfish have no brain, heart, bones or blood. A simple nerve net lets them sense their surroundings and react, and their bodies are about 95 percent water.
Q2: Jellyfish belong to which group of animals?
Answer: Cnidarians
Despite the name, jellyfish are not fish. They are cnidarians, related to corals and sea anemones, all of which have stinging cells.
Q3: Which jellyfish is considered one of the most venomous animals in the world?
Answer: Box jellyfish
The Australian box jellyfish, Chironex fleckeri, has venom that can kill a person within minutes. Swimmers in northern Australia wear stinger suits in summer.
Q4: Which jellyfish is one of the largest, with tentacles that can stretch more than 30 meters?
Answer: Lion's mane
The lion's mane jellyfish lives in cold northern waters. Its tentacles can be longer than a blue whale.
Q5: Roughly how long have jellyfish existed on Earth?
Answer: Over 500 million years
Jellyfish fossils date back more than 500 million years, making them older than dinosaurs, sharks and trees.
Q6: What is one name for a group of jellyfish?
Answer: A smack
A group of jellyfish can be called a smack or a bloom. Huge blooms can clog fishing nets and power-station water intakes.
Q7: What are the tiny stinging cells of jellyfish called?
Answer: Nematocysts
Nematocysts fire tiny harpoons when touched, injecting venom. Even dead jellyfish on a beach can still sting.
Q8: A glowing protein first found in the crystal jelly won scientists a 2008 Nobel Prize in which field?
Answer: Chemistry
Green fluorescent protein, or GFP, from the jellyfish Aequorea victoria is now used to make cells glow so scientists can study them.
Q9: What is the Portuguese man o' war, often mistaken for a jellyfish?
Answer: A colony of organisms
The Portuguese man o' war is a siphonophore, a colony of tiny specialized animals working together. It floats with a gas-filled sail.
Q10: Which sea turtle feeds mainly on jellyfish?
Answer: Leatherback
Leatherbacks, the largest turtles, eat huge amounts of jellyfish. Plastic bags in the ocean can look like jellyfish and are dangerous for them.

Jellyfish Quiz – Ancient Drifters of the Sea

Jellyfish have been drifting through the oceans for more than 500 million years, long before dinosaurs, fish with jaws or trees appeared. They have no brain, no heart and no bones, yet they have survived every mass extinction and can be found in every ocean, from the surface to the deep sea.

A jellyfish's body is simple but effective. Its bell pulses to push it through the water, and its tentacles are armed with thousands of stinging cells that fire tiny harpoons to catch prey. Most stings are mild for humans, but a few species, such as the box jellyfish of Australia, are among the most dangerous animals on Earth.

Jellyfish also have surprising talents. Many glow with bioluminescence, and a protein from one species became a key tool in modern biology, earning a Nobel Prize. Some jellyfish can even turn back into an earlier stage of life, which has made them a subject of research into aging.

In recent decades, huge jellyfish blooms have become more common in some regions, possibly helped by overfishing, warmer water and pollution. At the same time, jellyfish are an important food for animals such as leatherback turtles and sunfish, and in parts of Asia they are eaten by people too.

This quiz explores the biology, records and surprises of jellyfish.

Beachgoers can avoid most stings by watching for warning flags, wearing protective suits where box jellyfish live and never touching jellyfish washed up on the sand. Lifeguards in many countries keep vinegar or other first-aid supplies ready during jellyfish season.

What This Quiz Teaches

This quiz is ideal for ocean lovers, divers, beachgoers and students of marine life.

How jellyfish live without a brain or heart
Why jellyfish are not really fish
Which jellyfish are the most dangerous and the largest
How stinging cells work
How a jellyfish protein won a Nobel Prize
What the Portuguese man o' war really is

Quick Facts About Jellyfish

Some jellyfish are smaller than a fingernail.
Vinegar is used to treat stings from some jellyfish, but not all.
Moon jellyfish were taken into space aboard the space shuttle in 1991.
Ocean sunfish, the heaviest bony fish, eat mostly jellyfish.
Jellyfish are served as a crunchy salad in parts of China and Japan.
Some aquariums display jellyfish in special round tanks that keep them from getting stuck.