We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What are Cnidarians?

Michael Anissimov
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Cnidarians are a relatively simple phylum of animals (one among 38) which include the jellyfish, corals, sea pansies, sea pens, box jellies, and sea wasps. The phylum gets its name Cnidaria, from the Greek "cnidos," meaning "stinging needle."

All cnidarians, including the stationary corals (the builders of the famous and beautiful coral reefs) have stinging cells called cnidocytes, which get their sting from organelles called nematocysts (also called cnidocytes or cnidoblasts). Cnidarians are thought to be among the most basal of all animals, excepting the sponges, and fossils dating to the Ediacaran period, 580 million years ago. Cnidarians left some of the first clearly identifiable animal fossils.

There are over 10,000 species of cnidarian, divided into four main classes: Anthozoa (anemones, corals), Scyphozoa (true jellyfish), Cubozoa (box jellies) and Hydrozoa (Obelia, Aequorea, Portuguese Man o' War, others.) Two additional minor groups include Polypodium (strange parasitic cnidarians, one of the few animals to live in the cells of other animals) and Myxozoa, tiny fish/worm parasites. The classification of the latter two groups within Cnidaria is relatively recent and was made possible by genetic analysis.

Cnidarians have a reputation for being beautiful but painful, or even deadly. Each year, thousands of people are stung by jellyfish, resulting in extreme pain for many, and even death for a few. In Australia and other high-risk places, choice beaches are fenced off using nets, to protect swimmmers from the painful cnidarian touch. Particularly dangerous are the box jellies, and one species, the Irukandji jellyfish, is thought to be one of the most venomous animals on the planet. One victim stated, "I didn't think it was possible for anyone to endure that level of pain without turning into a vegetable."

Cnidarians (coral) make up the world's largest superorganism, the Great Barrier Reef in Australia, which covers an area of about 344,400 square km (132,974 sq mi). This reef, and many others around the world, have grown bit by bit over thousands of years, as coral polyps die, leaving behind their skeletons, then budding off to form new stretches of reef. These reefs are home to many sea animals, including the majestic green sea turtle.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Anissimov
By Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology, astronomy, chemistry, and futurism to his articles. An avid blogger, Michael is deeply passionate about stem cell research, regenerative medicine, and life extension therapies. His professional experience includes work with the Methuselah Foundation, Singularity Institute for Artificial Intelligence, and Lifeboat Foundation, further showcasing his commitment to scientific advancement.
Discussion Comments
Michael Anissimov
Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology...
Learn more
All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.