Jellyfish are fascinating and ancient creatures that have been drifting through oceans for millions of years. Despite their name, jellyfish are not actually fish; they are invertebrates and belong to the phylum Cnidaria. These gelatinous animals come in many shapes, sizes, and colors, and some species are known for their beautiful glow. Let’s explore some of the different types of jellyfish, as well as interesting facts and frequently asked questions about them.
Table of Contents
- Types of Jellyfish
- Moon Jellyfish (Aurelia aurita)
- Box Jellyfish (Chironex fleckeri)
- Lion’s Mane Jellyfish (Cyanea capillata)
- Portuguese Man O’ War (Physalia physalis)
- Cannonball Jellyfish (Stomolophus meleagris)
- Upside-Down Jellyfish (Cassiopea spp.)
- Mauve Stinger Jellyfish (Pelagia noctiluca)
- Atolla Jellyfish (Atolla wyvillei)
- Irukandji Jellyfish (Carukia barnesi)
- Crystal Jellyfish (Aequorea victoria)
- Fun Facts About Jellyfish
- Frequently Asked Questions About Jellyfish
Video: Nat Geo Wild
Types of Jellyfish
Moon Jellyfish (Aurelia aurita)
- Description: The moon jellyfish is one of the most common types of jellyfish found in oceans around the world. It has a translucent, saucer-shaped bell with four horseshoe-shaped gonads visible through its bell. The tentacles are short and delicate.
- Habitat: Moon jellyfish are found in coastal waters, particularly in temperate and tropical seas.
- Diet: They primarily feed on plankton, including small fish and other tiny marine organisms.
- Fun Fact: Moon jellyfish glow in the dark through a process called bioluminescence, creating an enchanting effect in the water.
Box Jellyfish (Chironex fleckeri)
- Description: The box jellyfish, also known as the sea wasp, is infamous for its powerful sting. Its bell is shaped like a cube, and it has tentacles that can grow up to 10 feet long.
- Habitat: Box jellyfish are found in the waters of the Pacific Ocean and Indian Ocean, particularly around northern Australia.
- Diet: They prey on small fish and shrimp, using their venomous tentacles to capture prey.
- Fun Fact: The sting of a box jellyfish can be extremely dangerous to humans, and in severe cases, it can be fatal.
Lion’s Mane Jellyfish (Cyanea capillata)
- Description: The lion’s mane jellyfish is one of the largest types of jellyfish in the world. Its bell can reach up to 8 feet in diameter, and its long, flowing tentacles resemble a lion’s mane.
- Habitat: Found in the colder waters of the North Atlantic, North Pacific, and Arctic Oceans.
- Diet: They feed on small fish, plankton, and other jellyfish.
- Fun Fact: The lion’s mane jellyfish has tentacles that can grow up to 120 feet long, making them one of the longest animals in the world.
Portuguese Man O’ War (Physalia physalis)
- Description: Often mistaken for a jellyfish, the Portuguese Man O’ War is actually a siphonophore, a colony of specialized individuals working together. Its gas-filled, bluish-purple float sits on the water’s surface, while long tentacles dangle beneath.
- Habitat: Found in warm waters, including the Atlantic Ocean, Indian Ocean, and Pacific Ocean.
- Diet: They feed on small fish and plankton, using their stinging tentacles to paralyze prey.
- Fun Fact: The sting of a Portuguese Man O’ War is very painful to humans and can cause severe reactions, although it is rarely fatal.
Cannonball Jellyfish (Stomolophus meleagris)
- Description: The cannonball jellyfish is named for its round, firm, cannonball-shaped bell. It is relatively small compared to other types of jellyfish, typically growing to around 10 inches in diameter.
- Habitat: Commonly found in the waters of the Gulf of Mexico and along the southeastern coast of the United States.
- Diet: Cannonball jellyfish feed on plankton and other small marine organisms.
- Fun Fact: Unlike many other jellyfish, the sting of the cannonball jellyfish is mild and poses little threat to humans.
Upside-Down Jellyfish (Cassiopea spp.)
- Description: The upside-down jellyfish gets its name from its habit of resting on the ocean floor with its bell facing downward and its tentacles extended upward. It has a flat, circular bell and delicate, frilly tentacles.
- Habitat: Found in shallow, tropical waters, particularly in mangroves and lagoons.
- Diet: Upside-down jellyfish have symbiotic relationships with algae, which live in their tentacles and provide nutrients through photosynthesis.
- Fun Fact: These jellyfish can also absorb sunlight through their symbiotic algae, allowing them to survive with minimal food intake.
Mauve Stinger Jellyfish (Pelagia noctiluca)
- Description: The mauve stinger is a small, purplish-pink jellyfish known for its beautiful color and ability to glow in the dark. Its bell is about 4-6 inches in diameter and is covered with small, stinging cells.
- Habitat: Found in the Mediterranean Sea and the Atlantic Ocean.
- Diet: They feed on zooplankton, small fish, and other jellyfish.
- Fun Fact: The mauve stinger is bioluminescent and can light up the water around it when disturbed.
Atolla Jellyfish (Atolla wyvillei)
Video: Ocean Networks Canada
- Description: The Atolla jellyfish is known for its crown-like bell and bright bioluminescence. It produces flashes of light when it’s attacked, which may act as a defense mechanism to confuse predators.
- Habitat: Found in deep ocean waters around the world.
- Diet: Atolla jellyfish feed on small plankton and other tiny marine organisms that they catch with their tentacles in the deep ocean.
- Fun Fact: The Atolla jellyfish is sometimes called the “alarm jellyfish” because it lights up when threatened, attracting larger predators to scare away its attacker.
Irukandji Jellyfish (Carukia barnesi)
- Description: This tiny box jellyfish is about the size of a thumbnail, but it packs a potent sting that can cause Irukandji syndrome, a potentially life-threatening condition.
- Habitat: Found in northern Australia’s coastal waters.
- Diet: The Irukandji jellyfish primarily preys on small fish and plankton, using its venomous tentacles to stun and capture its food.
- Fun Fact: Despite its small size, the Irukandji jellyfish can cause severe pain, nausea, and in rare cases, heart complications.
Crystal Jellyfish (Aequorea victoria)
- Description: The crystal jellyfish is nearly transparent, with a delicate, glass-like appearance. It is known for producing one of the brightest bioluminescent glows, thanks to a special protein called GFP (Green Fluorescent Protein).
- Diet: Crystal jellyfish consume small plankton, fish larvae, and other tiny marine organisms, using their tentacles to paralyze and capture prey.
- Habitat: Found in the waters off the west coast of North America.
- Fun Fact: GFP from the crystal jellyfish has been used extensively in scientific research, earning it a Nobel Prize in chemistry.
Fun Facts About Jellyfish
Jellyfish Are Among the Oldest Creatures on Earth
Jellyfish have been around for more than 500 million years, meaning they existed long before dinosaurs walked the planet.
No Brain, Heart, or Bones
Jellyfish are simple creatures with no brain, heart, or bones. Their body is made up of 95% water, and they use a network of nerves (a “nerve net”) to detect changes in their environment.
Jellyfish Are Mostly Transparent
Because they are composed of mostly water, jellyfish are nearly invisible in their natural habitats, making it hard for predators to spot them.
Some Jellyfish Are Bioluminescent
Many types of jellyfish, like the moon jellyfish and mauve stinger, can glow in the dark through bioluminescence. This glow can serve multiple purposes, from attracting mates to confusing predators.
Jellyfish Can Clone Themselves
If a jellyfish is cut in half, both halves can regenerate into two new jellyfish! Some species can also clone themselves if injured or broken apart.
The Immortal Jellyfish
The species Turritopsis dohrnii, known as the “immortal jellyfish,” can revert to its juvenile form after reaching adulthood, effectively making it biologically immortal under the right conditions.
Jellyfish Migrations
Some types of jellyfish migrate daily, moving from deeper waters during the day to shallow waters at night. They follow the vertical migration of plankton, their main food source.
World’s Largest Jellyfish
The lion’s mane jellyfish is the largest known species of jellyfish. Its bell can reach up to 8 feet in diameter, and its tentacles can extend over 120 feet, making it one of the longest animals in the world.
Jellyfish Can Shrink
When food is scarce, some types of jellyfish can shrink to a smaller size to conserve energy. They can return to their normal size once they find more food.
Jellyfish Don’t Swim Far
Despite their ability to move by pulsating their bell, jellyfish are mostly carried by ocean currents. They are considered planktonic organisms because they drift with the water.
Jellyfish as a Delicacy
In some cultures, jellyfish are considered a delicacy and are used in dishes like salads. The jellyfish is dried and salted to remove water, giving it a crunchy texture.
Frequently Asked Questions About Jellyfish
There are over 2,000 species of jellyfish, and scientists believe there may be even more undiscovered species living in the deep ocean.
No, not all jellyfish are dangerous to humans. While some, like the box jellyfish and Portuguese Man O’ War, have venomous stings that can be harmful or even fatal, many species, such as the moon jellyfish, have mild stings that pose little threat to humans.
A box jellyfish sting can be extremely dangerous, but if treated quickly with medical care, survival is possible. Applying vinegar to the sting can help neutralize the venom, and medical attention should be sought immediately.
Jellyfish are carnivores that feed on plankton, small fish, crustaceans, and even other jellyfish. They use their stinging tentacles to capture and paralyze prey before consuming it.
Jellyfish have complex life cycles and can reproduce both sexually and asexually. Some species release eggs and sperm into the water for external fertilization, while others can clone themselves or produce polyps that give rise to new jellyfish.
Yes, jellyfish tentacles can still sting even after the jellyfish is dead. The stinging cells, or nematocysts, can be triggered by contact, so it’s important to avoid touching jellyfish washed up on the beach.
Yes, jellyfish have natural predators, including sea turtles, sunfish, some species of fish, and seabirds. Despite their stinging cells, jellyfish play an important role in the marine food web.
Jellyfish use their stinging cells, called nematocysts, to defend themselves and capture prey. When a jellyfish’s tentacles touch something, these cells release venom that can paralyze or kill small creatures.
Most jellyfish live in saltwater, but there are a few species, like the freshwater jellyfish (Craspedacusta sowerbyi), that can survive in lakes and rivers.
Many jellyfish glow through a process called bioluminescence, where chemicals in their bodies produce light. This can help jellyfish evade predators or attract prey by illuminating their surroundings.
The lifespan of a jellyfish varies by species. Some jellyfish only live for a few months, while others can live for several years. The immortal jellyfish (Turritopsis dohrnii) can theoretically live indefinitely by reverting back to its juvenile form.
Jellyfish blooms are large gatherings of jellyfish that occur when conditions are ideal, such as abundant food and favorable water temperatures. During a bloom, thousands or even millions of jellyfish can appear in a single area, sometimes disrupting fishing or beach activities.
Yes, jellyfish have an incredible ability to regenerate. Some species can regrow damaged parts or even revert back to their juvenile form and start their life cycle again.
Jellyfish play a vital role in marine ecosystems as both predators and prey. They help control populations of plankton and small fish, and they serve as food for many marine animals, including sea turtles and large fish.
Jellyfish are some of the most intriguing creatures in the ocean. From their ancient history and simple anatomy to their diverse species and unique survival strategies, jellyfish continue to captivate scientists and ocean enthusiasts alike. Whether glowing in the dark, drifting with ocean currents, or defending themselves with venomous tentacles, jellyfish are a crucial part of marine life.
Gabrielle Kotkov is an AMI-trained 3-6 Montessorian and educational consultant. She has a Master's Degree in Child Studies and is certified in TESOL (Teaching English to Speakers of Other Languages). She is particularly interested in the intersection between Montessori education and multilingualism, which led her to create the Multilingual Montessori website and podcast. Gabrielle has taught in schools in NYC, Sicily, London, and Austin, and is currently on the teaching faculty of the West Side Montessori School Teacher Education Program, an AMS training center in NYC.