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 the Ecdysozoa?

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.

Ecdysozoa is a proposed super-grouping of eight animal phyla (out of approximately 37) -- Arthropoda, Onychophora, Tardigrada, Kinorhyncha, Priapulida, Loricifera, Nematoda and Nematomorpha. It is a controversial grouping, but a large genetic study in Nature in 2008, "Broad phylogenomic sampling improves resolution of the animal tree of life," strongly supported the Ecdysozoa as a natural category. The group was originally proposed as the result of genetic studies using 18S ribosomal RNA genes in 1997.

The primary characteristic the Ecdysozoa share is the molting of a three-layered cuticle in a process called ecdysis (from whence the group gets its name). Another shared feature is the absence of locomotory cilia in reproductive cells -- the sperm are amoeboid. Ecdysozoa embryos do not undergo spiral cleavage, while other protostome embryos do. The Ecdysozoa are all protostomes, one of the two major groups of animals, the other being deuterostomes.

Ecdysozoa is a proposed superphylum within Bilateria, an unranked subregnum (subkingdom) within animals in general. Its largest group is the arthropods, which includes all insects, crustaceans, and arachnids, and is estimated of including a total of 5-8 million species, the majority of all animal life. The Ecdysozoa are the most numerous and prolific organisms on the planet, and their combined biomass exceeds that of all seven billion or so humans.

The Ecdysozoa includes what were some of the earliest forms of life to evolve hard shells, such as the arthropod trilobites, whose emergence defines the start of the Cambrian period, 542 million years ago, and the first forms of life to venture onto the land. The earliest land animal fossil, Pneumodesmus newmani, a 1-cm millipede, is a member of Ecdysozoa. It is likely that nematodes, which cover the abyssal plains of the oceans and are the most numerous multicellular life form on Earth, were actually the first on land, but they don't fossilize well.

Ironically, the cuticle of nematodes have a different chemical composition than all the other Ecdysozoa, so their membership within the group is also the most suspect. One microscopic member of Ecdysozoa, the tardigrades, are notable for being able to withstand extreme temperatures and radiation that would kill a human hundreds of times over. They are the only animal that could survive the rigors of outer space for any significant length of time.

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.