Crystal Jellyfish: Anatomy, Habitat, Diet & Other Facts

The scientific name of the crystal jellyfish is Aequorea victoria. These marine animals are sometimes called hydromedusa or bioluminescent hydrozoan jellyfish. These sea jellies are popularly known due to their translucent appearance. The west coast of North America is the place of these aquatic friends.

Besides these, they are also known as one of the most ethereal, mesmerizing marine creatures in the waters. Their bodies almost float through the water like delicate, otherworldly beings. These are part of a family of comb jellies and are found all over the world. These crystal-like jellies are quite resilient and adaptive to a wide range of conditions.

Have you ever wondered about how crystal jellyfish reproduce? Do you want to know why they are crystal jellies? If so, you’re in for a treat. In this article, we are diving deep into the marvelous world of these specialized species of sea jellies. Just read on and discover the answers to all of your questions here!

Crystal Jellyfish

All About Crystal Jellyfish – A Quick Biology

Here is a table of quick biology facts about crystal jellyfish:

Scientific nameAequorea victoria(Murbach and Shearer, 1902)
SpeciesA. victoria
HabitatThe West Coasts of North America
Life SpanMore than 2 years
DietCopepods, other sea jellies, ctenophores
Size/length2 to 40 cm in diameter or more than 2 meters, sometimes

Description and Anatomy of Crystal Jellyfish

Crystal jellyfish is known as one of the unique species of jellyfish. These are named crystal jellyfish due to their transparent bodies. Their ability to glow in the dark makes them more interesting and captivating. These species of jellyfish have two proteins in their bodies that involve bioluminescence. These include the following: 

  • Green fluorescent protein (GFP)
  • Aequorin (a photoprotein)

Osamu Shimomura and his colleagues discovered the green fluorescent protein (GFP) in crystal jellyfish. Their work on GFP was groundbreaking and led to many scientific advancements. The research team was awarded the 2008 Nobel Prize in Chemistry for their contributions. The discovery of GFP has helped researchers better understand many biological processes. 

Aequorea victoria is the scientific name of the crystal jellyfish. It is named after the Aequorea genus and where it was first discovered – Victoria, British Columbia. They are part of the family Aequoreidae. This family belongs to the order Beroida in the phylum Ctenophora. The scientific classification of crystal jellyfish is given in the table above. 

Physical Appearance of Crystal Jellyfish

Crystal jellyfish are colorless. These are transparent in nature. The diameter of crystal jellyfish is usually 10 centimeters. A highly contractile mouth and manubrium are at the center of the crystal jellyfish’s bell-shaped body. Extending from this center are up to 100 radial canals that reach out to the margins of the jellyfish’s body. 

Crystal jellyfish have up to 150 uneven tentacles that surround the margin of their bell-shaped bodies. These tentacles are present in fully-grown specimens. The tentacles of crystal jellyfish are equipped with nematocysts that help them capture prey. These nematocysts are harmless to humans.

Individuals that are over 3 cm in size have gonads for sexual reproduction. The gonads run along most of the length of the radial canals and can be seen as white thickenings in photos of the jellyfish. The muscular velum surrounds the bell margin of crystal jellyfish and helps with movement.

The vellum is a common feature in hydromedusae, a class of jellyfish. Larger crystal jellyfish specimens often have symbiotic hyperiid amphipods attached to their subumbrella. These amphipods can sometimes even be found living inside the gut or radial canals of jellyfish.

Behavior of Crystal Jellyfish

Here are a few behaviors of crystal jellyfish:

Migration Behavior

Crystal jellyfish migrate vertically in the water column in response to light and temperature changes. During the day, they can be found deeper in the water to avoid predation and photodamage. At night, they move towards the surface to feed and breed.


When threatened, crystal jellyfish exhibit self-protection behaviors such as swimming away quickly, curling up into a ball, or releasing their tentacles to escape. They also have nematocysts in their tentacles for defense.

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Buoyancy control

Crystal jellyfish can control their buoyancy by adjusting the amount of water they hold in their bell. They can also contract their bell muscles to force water out, allowing them to move up in the water column.

Bioluminescence behavior, feeding behavior, and reproductive behavior are given in their prior sections. You can also take a look at them.

Symbiotic relationships

Crystal jellyfish have symbiotic relationships with various organisms, such as amphipods and copepods, which live inside the jellyfish’s bell or tentacles. These organisms provide protection and receive nutrients in return.


Crystal jellyfish exhibit phototactic behavior, meaning they are attracted to light. This can sometimes lead them to wash up on beaches accidentally. They also become trapped in fishing nets due to this behavior.

Regeneration behavior

Like other jellyfish, crystal jellyfish are capable of regenerating lost body parts, such as tentacles or sections of their bell.

Aggregation behavior

Crystal jellyfish are known to aggregate in large groups. This behavior can affect nutrient cycling and food webs in their ecosystem.

Crystal Jellyfish in water

Habitat, Range, and Distribution

A research team in Alaska to central California coastal areas found that crystal jellyfish are native to the Pacific Ocean along the western coast of North America. The medusa form of the jellyfish is a pelagic organism. It develops from a polyp on the ocean floor in late spring. These jellyfish can be found floating and swimming nearshore and offshore in the eastern Pacific Ocean

These sea jellies are common in Puget Sound, located in the northwestern United States. A surprising event occurred when a crystal jellyfish was found in the Moray Firth in Scotland in September 2009. This was the first time crystal jellyfish had been observed in British waters. 

This crystal jellyfish was displayed at the Macduff Marine Aquarium in Aberdeenshire for visitors to see. This occurrence sparked curiosity among researchers and the public about how and why the jellyfish ended up in such an unexpected location.

Feeding Habits/ Diet

According to the study, crystal jellyfish love to consume soft-bodied organisms. Some of the few organisms on which it depends include the following:

  • Crustacean zooplankton such as barnacle nauplii, crab zoëals, copepods & other larval planktonic organisms
  • Ctenophores
  • Appendicularians
  • Other hydromedusae (like Aequorea victoria)

Crystal jellyfish capture their prey using long tentacles that contain nematocysts. The crystal jellyfish possesses a mouth that is capable of contracting strongly. It can stretch to engulf organisms that are up to half of its size.

They are known for their voracious nature, which can lead to competition in shared environments. The density of Aequorea victoria is inversely correlated to zooplankton density, suggesting a competitive presence.

According to the NCBI research, we have found the following feeding behavior of a crystal jellyfish:

“Crystal jellyfish do not become better swimmers as they grow larger. This makes them inefficient swimmers. Thus, they rely on coming in direct contact with their prey for feeding. This is achieved through energetic propulsion. This technique involves using pressure to passively move in their environment and reach their prey.”

Life Cycle and Reproduction System

Crystal jellyfish have a dimorphic life cycle. It alters between the following two stages:

  • Sexual planktonic medusae
  • Asexual benthic polyps

In late spring, juvenile medusae are budded off hydroid colonies asexually. These free-living hydromedusae spend their entire life in the plankton. The medusa grows quickly and produces gametes after reaching about 3 cm in size. Each medusa is either male or female.

Eggs and spermatozoa mature in the medusa’s gonads. They are free-spawned into the water column in response to a daily light cue when there is enough food. They are then fertilized and eventually settle to form a new hydroid colony. 

Hydroids live on hard or rocky substrates on the bottom. This is where they asexually bud new jellyfish each springtime in response to environmental cues. The medusa form typically lives for about 6 months, from late spring to autumn. The lifespan of a mature jellyfish is two years. 

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Cardiovascular and Nervous Systems

Cardiovascular System

The cardiovascular system of crystal jellyfish consists of a simple arrangement of canals that transport fluid throughout the jellyfish’s bell. The fluid, or hemolymph, helps to distribute nutrients and oxygen throughout the body. 

There is no specialized heart in jellyfish, but the bell’s contractions can help move hemolymph through the canals. The lack of a complex cardiovascular system limits the size that jellyfish can grow to.

Nervous System

The nervous system of crystal jellyfish comprises a simple network of nerve cells called a nerve net. This nerve net is spread throughout the jellyfish’s body. It helps to coordinate the jellyfish’s movement and responses to stimuli.

The nerve net is responsible for the jellyfish’s ability to sense light, touch, and chemicals in the water. However, the jellyfish lacks a centralized brain or complex sensory organs. It limits its ability to exhibit complex behaviors.

Importance of Crystal Jellyfish in the Ecosystem

Crystal jellyfish, like other jellyfish species, play a vital role in marine ecosystems. They are an important food source for many marine predators like sea turtles, sunfish, and some species of birds. Additionally, they feed on small zooplankton. It helps to regulate the populations of these organisms in the water column.

Their waste products also contribute to nutrient cycling in the ocean. This is crucial for the growth and survival of many other marine organisms. Furthermore, crystal jellyfish can serve as indicators of environmental health. The changes in their populations can signal ocean conditions and water quality changes.

Predators of Crystal Jellyfish

Crystal jellyfish are preyed upon by various aquatic organisms. Some of their predatory animals include the following:

Additionally, cannibalism has been documented among crystal jellyfish. Parasitic hyperiid amphipods are often found attached to larger specimens of these sea jellies. However, they do not pose a lethal threat to the jellyfish.

Relationship with Humans 

Crystal jellyfish have the following relationship with humans:

Relationship with Humans – Positive

The bioluminescence of Aequorea jellyfish has been used as a research tool in biomedical sciences like genetic research and protein labeling. The green fluorescent protein (GFP) found in crystal jellyfish has also been widely used in biological research.

The discovery of GFP and its derivatives has led to many medical advancements. Additionally, Aequorea jellyfish are also considered a delicacy in some Asian countries, where they are consumed in salads and soups.

Relationship with Humans  – Negative

Crystal jellyfish are not known to cause significant harm to humans. However, their presence in large numbers can be a nuisance to fishermen and may cause damage to fishing gear. Additionally, the accidental introduction of non-native species of jellyfish, including Aequorea jellyfish, into new environments can negatively impact local ecosystems. 

They can cause problems for commercial activities like aquaculture and tourism. In some areas, jellyfish blooms have caused temporary closures of beaches due to the potential for painful stings to humans.

Crystal Jellyfish in dark water

How to Identify a Crystal Jellyfish?

Identifying a crystal jellyfish can be challenging. It is because the features used for identification are variable and increase with the jellyfish’s size. These features may include the number of tentacles, radial canals, and marginal statocysts. Crystal jellyfish belong to the Aequorea.

The Aequorea species also includes a similar species called Aequorea coerulescens. It is larger and has more radial canals. Morphological identification of the species can be difficult due to intermediate forms and variations in appearance. The crystal jellyfish is thought to be synonymous with Aequorea aequorea.

Also, the names were originally used to differentiate between specimens found in the Pacific and those found in the Atlantic and Mediterranean. However, the species name used in GFP purification was later disputed by M.N. Arai and A. Brinckmann-Voss. It was based on 40 specimens collected from Vancouver Island. 

Crystal Jelly Bioluminescence: A Fascinating Phenomena 

According to a Chicago journal, the crystal jellyfish has a fascinating ability to emit flashes of blue light. These flashes are emitted through the release of calcium ions that interact with the photoprotein aequorin. The blue light produced is then transformed into green light. It happens by the renowned green fluorescent protein (GFP). 

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This process is known as Förster resonance energy transfer (FRET). Both aequorin and GFP are highly valuable fluorescent markers used in biochemical research. This unique ability to produce bioluminescence has been studied for potential applications in various fields like biotechnology and medical imaging.

Shimomura and Johnson researched Aequorea jellyfish at Friday Harbor Laboratories in 1961. They isolated a protein called aequorin and its small molecule cofactor coelenterazine. They discovered that calcium ions (Ca2+) were necessary to trigger bioluminescence after observing bright luminescence in a purified sample.

Ridgeway and Ashley microinjected aequorin into single muscle fibers of barnacles. They observed calcium ion-dependent signals during muscle contraction.

According to another study, crystal jellyfish possess more than 100 mini-organs that can easily produce light. This is because they have excellent bioluminescence. 

The discovery of green fluorescent protein led to significant progress in the medical field, as we have mentioned before. It provides further insight into the treatment and diagnosis of diseases through research in cells and bacteria. 

This breakthrough has opened up new possibilities for medical research. It allows scientists to understand biological processes at the molecular level better, and develop new therapies for various diseases.

Growing Numbers of Crystal Jellyfish in UK Seas

The research given by The Guardian discusses the increasing presence of unusual jellyfish in the UK. These sea jellies also include crystal jellyfish. This is due to the effects of the climate crisis. Warmer sea temperatures have led to the arrival of new jellyfish species.

This change can impact the fishing industry and cause harm to swimmers. The jellyfish also disrupt the food chain and can negatively impact marine ecosystems. More research is needed to understand the implications of these growing numbers fully. However, it highlights the importance of addressing the root causes of the climate crisis.

According to the research, we have found the following facts: 

“These crystal jellyfish can pose a threat to humans, as their stings can cause pain and in severe cases, even death. In a week in 2019, over 1,200 people were stung by jellyfish in just one area in Australia.”

These occurrences emphasize the need to understand better the relationship between the changing climate and the rise of jellyfish populations. It is to take measures to protect marine life and humans from their negative impacts.


Can crystal jellyfish sting you?

Yes, crystal jellyfish can sting you. However, there is no need to be worried more about these sea jellies. It is because their venom is not harmful or lethal for humans. They can only cause redness or rashes after a sting.

Do crystal jellyfish eat fish?

No. Crystal jellyfish only eat small organisms such as larval fish and fish eggs. There is a possibility that they also eat small fish, but it’s not been observed yet.

Are jellyfish 600 million years old?

Yes, jellyfish have been around for at least 600 million years. They are some of the oldest creatures on Earth. Jellyfish belong to the phylum Cnidaria, which first appeared in the fossil record about 600 million years ago.

Some of the earliest jellyfish fossils date back to the Ediacaran period, which began over 600 million years ago. Jellyfish have been on Earth for a very long time and have evolved and adapted in many different ways. However, it’s still unknown whether crystal jellyfish are 600 million years old.

Are crystal jellyfish rare?

Crystal jellyfish are common species of jellyfish mostly found in the northern waters of the Pacific Ocean. However, these sea jellies are rare in the waters of the UK. Usually, they are only available in the East Pacific regions.

How much of a crystal jellyfish is water?

Crystal jellyfish are composed mainly of water, like most jellyfish. In fact, up to 95% of their body is water. This allows them to be very buoyant and to move easily through the water column. The remaining 5% of their body comprises various proteins, lipids, and other organic molecules.


It’s been a joy to discuss crazy and interesting facts about crystal jellyfish. Hope you also enjoyed this journey about these fascinating aquatic animals. They have been around for a long time and continue to thrive in our oceans. Let’s continue to appreciate and protect them!

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