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What does this page offer?

  • Read about the basic facts on cnidaria
  • Access some of the free short courses on cnidaria
  • Join OZT as a member to learn even more about how to work with cnidaria while meeting people from around the world!

You have chosen a career to follow and prepare for; now it’s time to learn more about the species you will work with.

  • Read about the basic facts on cnidaria
  • Join the Cnidarias Group to learn how to work with them and meet people from around the world
  • Access all of the free short courses on cnidarias
  • Connect with tertiary institutions and organisations that work with cnidarias

Basic Facts on Cnidaria

The phylum Cnidaria includes many soft-bodied, aquatic animals with stinging cells. The name Cnidaria comes from the Greek word cnid- which means nettle, a stinging plant.

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Scientific name:


Common use names:

The cnidarians consist of the following species: jellyfish, hydroids, sea anemones, corals, sea pens, and box jellyfish.

Awesome fact:

Cnidarians have the ability to reorganise and regenerate their bodies

Important Dates:

580 million BC – Fossilised coral found in rock

Cnidaria Stats

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Average Length

up to an astonishing 38 meters (250 feet)

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Average Weight

Recorded at over 200 kilograms (440 lbs)


Average Lifespan

Few days to over 4000 years!


Average Offspring

up to 1000s of offspring produced in various ways, mostly through spawning where ova and sperm are released into the water

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Active Time

Both Diurnal and Nocturnal

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Main Diet


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Distribution & Habitat

Global distribution - all of them aquatic

Global Population

Estimated Global Population


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Conservation Status

Least Concerned to Endangered

The scientific classification of Cnidaria

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Kingdom: Animalia

Phylum: Cnidaria

Class: 4

Order: 15

Family: 441

Genus: 2,328

Species: 14,515

Do you have facts to contribute to this page? Please click on the red beetle to access the contribution form.

Free Short Courses on Cnidaria

The Top 3 Skills required to work with Cnidaria

Working with cnidaria, which includes organisms like jellyfish, corals, and sea anemones, often involves roles in marine biology, ecology, or aquarium management. Here are the top three skills required to work with cnidaria effectively:

Marine Biology and Taxonomy Knowledge:

  • Species Identification: An in-depth understanding of cnidarian species, their taxonomy, and classification is essential. This includes recognizing different species and understanding their unique characteristics and life cycles.
  • Ecological Understanding: Proficiency in marine ecology is crucial to comprehend the interactions between cnidaria and their environments. This includes knowledge of food webs, predator-prey relationships, and the impact of environmental factors on cnidarian populations.
  • Habitat Assessment: Being able to assess and monitor cnidarian habitats, such as coral reefs or coastal ecosystems, is vital. This skill involves understanding water quality, habitat health, and the effects of pollution or climate change.

Research and Data Analysis:

  • Field Research: Skills in conducting fieldwork, such as underwater surveys, specimen collection, and habitat assessments, are fundamental for marine biologists and ecologists studying cnidaria.
  • Data Collection: Proficiency in data collection methods, including using specialized equipment like underwater cameras, and recording observations accurately is essential.
  • Data Analysis: Competence in data analysis, including statistical methods and software, is crucial for drawing meaningful conclusions from research data.
  • Report Writing: The ability to communicate research findings effectively through reports, scientific papers, and presentations is vital for sharing knowledge and advancing the field.

Safety and Fieldwork Skills:

  • Safety Protocols: Knowledge of safety procedures in marine environments is critical to prevent accidents and ensure the well-being of both researchers and the cnidaria being studied.
  • Fieldwork Proficiency: Practical skills related to underwater fieldwork, such as SCUBA diving, snorkeling, or operating research vessels, are often necessary for studying cnidaria in their natural habitats.
  • Specimen Handling: Proper handling and care of cnidarian specimens, including collection, transportation, and maintenance in controlled environments, is essential for research and conservation efforts.

Working with cnidaria can be a rewarding but challenging endeavor due to the complex nature of marine ecosystems and the sensitivity of many cnidarian species to environmental changes. Developing a strong foundation in these skills, along with a passion for marine life and conservation, can lead to a successful career in the field of cnidarian research and management.

The Top 3 Tools used when working with Cnidaria

When working with cnidaria, particularly in research, marine biology, or aquarium management, various tools are essential to handle, study, and maintain these organisms. Here are the top three tools commonly used:


  • Dissecting Microscope: Dissecting microscopes, also known as stereo microscopes, are used for observing cnidaria in detail. They allow researchers to view specimens in three dimensions and are especially useful for examining small structures like nematocysts (stinging cells) and tissues.
  • Compound Microscope: Compound microscopes are essential for studying cnidarian cells and tissues at the cellular level. They provide higher magnification and are used for tasks such as histology, cytology, and identifying microscopic organisms that may be associated with cnidaria.
  • Polarizing Microscope: A polarizing microscope is valuable for examining the optical properties of cnidarian tissues and structures, particularly when studying coral skeletons, which are composed of calcium carbonate crystals.

Scuba Diving Equipment:

  • SCUBA Gear: When studying cnidaria in their natural habitats, SCUBA diving equipment, including masks, snorkels, fins, regulators, tanks, and buoyancy control devices, is crucial for underwater research and observations.
  • Underwater Cameras: Underwater cameras, both still and video, are used to document cnidarian behavior, habitat conditions, and species diversity in their natural environments.

Laboratory Equipment:

  • Aquarium Systems: For researchers and professionals managing cnidaria in aquariums or controlled environments, specialized systems for maintaining water quality, temperature, and lighting are essential. These include filtration systems, lighting fixtures, and water testing equipment.
  • Culture and Isolation Tools: When working with cnidarian cultures or isolating specific species or organisms, tools such as petri dishes, culture containers, pipettes, and sterilization equipment are necessary.
  • Laboratory Instruments: Depending on the research objectives, laboratory instruments such as microtomes (for tissue sectioning), centrifuges (for separating substances), and spectrophotometers (for analyzing chemical properties) may be used.

These tools are critical for studying cnidaria, whether in the field or in a controlled laboratory setting. They enable researchers to observe, manipulate, and analyze cnidarian specimens and data effectively, contributing to our understanding of these organisms and their roles in marine ecosystems.

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Join the Cnidaria Group

Learn even more about Cnidaria by joining the GROUP

Members of the Group can access all the different Short Courses, win awards and meet other Cnidaria lovers from around the world. Gain experience points with each short course and compete for the top spot on the leader board!

Topics covered in the CNIDARIA GROUP:

  • General Cnidaria knowledge (Anatomy, Habitat, Behaviour, Diet)
  • Ecological Benefits & Conservation
  • Creative (Including education, art, design, publishing, media, news and photography)
  • ​Species (courses on the prominent species)

Interact with all of the relevant tertiary institutions that feature courses related to cnidaria, as well as animal organisations that work with the species.

If you are not a member yet, then register for FREE!

Career profiles and resources

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Contributions by expert members are always appreciated to allow the students to learn about the species they will work with. Please add your contribution through the attached form:

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List of Species Mentors/Educators who have contributed to the info:


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A few excellent pictures as examples of the species:

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