ZME Science
No Result
View All Result
ZME Science
No Result
View All Result
ZME Science

Home → Environment → Animals

Jellyfish degenerates into mucus parasite: another amazing quirk of evolution

This may be the first known case of simplification from a macro to a microorganism, a cheap trick which evolution likely used more than once though.

Tibi PuiubyTibi Puiu
November 19, 2015
in Animals, Biology, News
A A
Share on FacebookShare on TwitterSubmit to Reddit

What’s an animal? That’s a harder question to answer than ever, given scientists found a group of microscopic parasites called myxozoans made up of just a few cells are in fact jellyfish. These look nothing like jellyfish, mind you, but the genetic analysis is unambiguous: these are still jellyfish.

Fresh spores of Myxobolus nagaraensis. How fitting that these look like alien heads since by all means they evolved so. Photo: T. Kageyama
Fresh spores of Myxobolus nagaraensis. How fitting that these look like alien heads since by all means they evolved so. Photo: T. Kageyama

According to Wikipedia, animals are multicellular, eukaryotic organisms of the kingdom Animalia. All animals are motile, meaning they can move spontaneously and independently, at some point in their lives. Yet again, we have these little buggers. “Animals are usually defined as macroscopic multicellular organisms, and this is not that. Myxozoa absolutely redefines what we think of as animal,” said Paulyn Cartwright of the University of Kansas.

Myxozoans make up a diverse group of more than 2,100 parasites. These usually plague commercial fish, and some parasite infections cause lethal effects. Non-lethal effects can include the production of small but obvious white cysts in the muscle that make fillets unsightly, unappetising and therefore unmarketable. Oddly enough, when the myxozoans reach the brain and spinal chord of trout and salmon they cause whirling disease which compel the fish to swim in circles. Peculiar beasts, but also elusive since it’s not clear how the myxozoans evolved.

Some have proposed these have evolved from single-celled organisms, but later DNA sequencing showed they were animals, or almost so. Almost since myxozoans lack the Hox genes, essential for embryonic development in animals.

Though they lack a gut and mouth, the structure of the myxozoans is complex resembling the  cells of cnidarians – a group that includes jellyfish, corals and sea anemones. What Cartwright and colleagues found after they sequenced the genomes of two distantly related myxozoan species is that these are in fact cnidarians.

Their genomes are 20 to 40 times smaller than a jellyfish. At  20 million base pairs, it’s actually one of the smallest genomes ever reported in an animal. For comparison, the human genome numbers  3 billion pairs of bases.

What we’re witnessing is retrograde evolution. Typically, an organism evolves from simplicity to complexity, but the reverse process happened to the myxozoans. In time, the myxozoans shed a lot of DNA and turned into a lesser organism. Perhaps, they weren’t parasites to begin with.

RelatedPosts

Scientists find potential antidote to world’s most venomous sea creature
In the future, we could be all snacking on jellyfish chips
Synthetic jellyfish made from rat heart cells can swim like the real deal
Inevitable Invasion? The Coming of the Jellyfish

This may be the first known case of simplification from a macro to a microorganism, a cheap trick which evolution likely used more than once though.

“First, we confirmed they’re cnidarians,” Cartwright said in the statement. “Now we need to investigate how they got to be that way.”

“It would be hard to recognize such animals because they would look so different from their closest relatives,” Cartwright said. “I think with new technologies such as whole-genome sequencing, we can better identify the evolutionary origins of some of these strange creatures.”

Tags: jellyfish

ShareTweetShare
Tibi Puiu

Tibi Puiu

Tibi is a science journalist and co-founder of ZME Science. He writes mainly about emerging tech, physics, climate, and space. In his spare time, Tibi likes to make weird music on his computer and groom felines. He has a B.Sc in mechanical engineering and an M.Sc in renewable energy systems.

Related Posts

Animals

This Benjamin Button-like Jellyfish Can Age in Reverse, From Adult to Juvenile

byTibi Puiu
9 months ago
Image credits: Jan Bielecki.
Animals

Jellyfish can learn just like humans — even though they lack a brain

byFermin Koop
2 years ago
Artistic reconstruction of a group of Burgessomedusa phasmiformis swimming in the Cambrian sea. Image credits: Christian McCall.
Animals

Scientists identify the oldest known species of swimming jellyfish

byFermin Koop
2 years ago
Invertebrates

This super rare spotted box jellyfish has only been recorded once before

byTibi Puiu
2 years ago

Recent news

The Worm That Outsourced Locomotion to Its (Many) Butts

May 16, 2025

The unusual world of Roman Collegia — or how to start a company in Ancient Rome

May 16, 2025
Merton College, University of Oxford. Located in Oxford, Oxfordshire, England, UK. Original public domain image from Wikimedia Commons

For over 500 years, Oxford graduates pledged to hate Henry Symeonis. So, who is he?

May 16, 2025
  • About
  • Advertise
  • Editorial Policy
  • Privacy Policy and Terms of Use
  • How we review products
  • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.

No Result
View All Result
  • Science News
  • Environment
  • Health
  • Space
  • Future
  • Features
    • Natural Sciences
    • Physics
      • Matter and Energy
      • Quantum Mechanics
      • Thermodynamics
    • Chemistry
      • Periodic Table
      • Applied Chemistry
      • Materials
      • Physical Chemistry
    • Biology
      • Anatomy
      • Biochemistry
      • Ecology
      • Genetics
      • Microbiology
      • Plants and Fungi
    • Geology and Paleontology
      • Planet Earth
      • Earth Dynamics
      • Rocks and Minerals
      • Volcanoes
      • Dinosaurs
      • Fossils
    • Animals
      • Mammals
      • Birds
      • Fish
      • Amphibians
      • Reptiles
      • Invertebrates
      • Pets
      • Conservation
      • Animal facts
    • Climate and Weather
      • Climate change
      • Weather and atmosphere
    • Health
      • Drugs
      • Diseases and Conditions
      • Human Body
      • Mind and Brain
      • Food and Nutrition
      • Wellness
    • History and Humanities
      • Anthropology
      • Archaeology
      • History
      • Economics
      • People
      • Sociology
    • Space & Astronomy
      • The Solar System
      • Sun
      • The Moon
      • Planets
      • Asteroids, meteors & comets
      • Astronomy
      • Astrophysics
      • Cosmology
      • Exoplanets & Alien Life
      • Spaceflight and Exploration
    • Technology
      • Computer Science & IT
      • Engineering
      • Inventions
      • Sustainability
      • Renewable Energy
      • Green Living
    • Culture
    • Resources
  • Videos
  • Reviews
  • About Us
    • About
    • The Team
    • Advertise
    • Contribute
    • Editorial policy
    • Privacy Policy
    • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.