Hallucigenia sparsa

Last updated: November 3, 2022
Verified by: AZ Animals Staff
© Dotted Yeti/Shutterstock.com

The position of the Hallucigenia's head puzzled scientists for several years


Hallucigenia Scientific Classification

Scientific Name
Hallucigenia sparsa

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Hallucigenia Conservation Status

Hallucigenia Locations

Hallucigenia Locations

Hallucigenia Facts

Fun Fact
The position of the Hallucigenia's head puzzled scientists for several years
Most Distinctive Feature
Hallucigenia had 10 pairs of legs
Distinctive Feature
Hallucigenia had seven pairs of rigid conical spines above its trunk
Bottom-dwelling creature in the Cambrian ocean
Prehistoric squids and lobsters
Special Features
Conical spines protected the Halluciginia against predators
Number Of Species

Hallucigenia Physical Characteristics

0.2–2.2 inches

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Hallucigenia is a worm-like creature that lived about 500 million years ago during the Cambrian Era. It belongs to a family of organisms known as lobopodians, believed to be ancestors of present-day velvet worms, water bears, and arthropods. Fossils of this strange-looking creature have been found in China, Canada, and other locations worldwide. 

Description and Size


The exact period of the Halluceigenia’s


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isn’t known, but they probably didn’t survive past the Cambrian-Ordovician extinction event, which occurred approximately 488 million years ago.

©Dotted Yeti/Shutterstock.com

Hallucigenia was one of the earliest life forms in the earth’s prehistoric ocean. It came on the scene about 500 million years ago, shortly after the Cambrian explosion. The thumb-sized worm belongs to a phylum of organisms that gave rise to present-day arthropods. At least three species have been identified in the genus with slight differences in their appearance. They include Hallucigenia sparsa, H. fortis, and H. hongmeia.

This creature’s “bizarre, dream-like quality” is the reason for its genus name. The strange-looking creature looked like something one would see in a dream. Hallucigenia had a short tubular body about 0.2 to 2.2 inches long. The animal had 10 pairs of slender legs, also known as lobopods. The first three pairs of legs had no extra features, while the remaining seven pairs terminated with one or two claws on their end. 

Because of the strange appearance of this creature, it took scientists several years to figure out its orientation and interpret some of its features. In addition to the 10 pairs of appendages, Hallucigenia also had seven pairs of rigid conical spines above its trunk. These are the only features on the trunk. The dorsal spines are slightly curved, each about 0.4 inches in length.  

Scientists had difficulty figuring out which end of the tubular body was the head. In the 2010s, it was revealed that the longer end, which extends beyond the legs and droops down, is the head. The study also revealed that the head had a sort of downward-facing mouth with radial teeth and at least one pair of simple eyes. Some specimens also have traces of a simple gut. 

Diet—What Did Hallucigenia Eat?

Scientists are not exactly sure of Hallucigenia’s diet. However, the structure of its body and mouth suggests a sort of suction-feeding habit. This animal probably fed by sucking water into its gut, while the rings of teeth around the mouth and gut area were not for chewing. Instead, it helped to keep any microscopic organisms caught in its throat from moving outwards. 

Habitat—When and Where Hallucigenia Lived

Hallucigenia fossils have been found in the Burgess Shale deposits in southeastern British Columbia in Canada. Fossils of this creature have also been found in the lagerstätten beds of China. These mineralized and carbonaceous fossils date back to the Cambrian Era, about 500 million years ago. 

Hallucigenia lived deep underwater. Light was probably scarce in this part of the Cambrian sea, but the creature had simple eyes that could tell day from night and could make out organisms swimming overhead. 

Although it had four pairs of floppy legs, scientists don’t think they were very useful for walking. At best, the creature probably used them to anchor itself to a sponge or seaweed in the water while feeding.  

Threats and Predators

The Cambrian sea probably didn’t have a lot of creatures swimming around, but there were quite a few nasty predators around. Scientists think some bizarre-looking prehistoric squids and lobsters may have attempted to feed on the Hallucigenia. However, this creature was not defenseless. Predators that went after it may have received a painful stab from the spines on its back. It is impossible to tell if the spines were venomous, but they probably served as an efficient protection against threats and predators. 

Discoveries and Fossils—Where Hallucigenia Was Found

Charles Walcott published the first description of the Hallucigenia in 2011. The description was based on fossilized remains recovered from the Burgess Shale of Southeastern British Columbia, Canada. However, earlier interpretations classified this organism as a polychaete. In 1977, an updated redescription was published by Simon Conway Morris. 

Morris categorized the organism into a distinct genus. Since the specimen he was working with did not show the rows of legs, he believed the animal walked on its spines and had tentacles for feeding. 

Up to 109 specimens of Hallucigenia have been recovered from the Greater Phyllopod bed of the Burgess Shale. This is just 0.3 percent of the community found in the fossil-rich bed. A few fossils have also been found in the Chinese lagerstätten beds. Scientists have also identified many isolated spines in Cambrian deposits across various locations worldwide. 

Extinction—When Did Hallucigenia Die Out?

Hallucigenia lived during the Cambrian about 505 million years ago. The creature evolved shortly after the Cambrian explosion, a period in geologic history characterized by the rapid evolution of various animal groups. The exact period of the Halluceigenia’s extinction isn’t known, but they probably didn’t survive past the Cambrian-Ordovician extinction event, which occurred approximately 488 million years ago.

Similar Animals to the Hallucigenia 

Similar animals to the Hallucigenia include: 

  • Anomalocaris — This is an extinct genus of bizarre-looking creatures that lived during the Cambrian. It is believed to be an ancestor of modern arthropods and one of the first apex predators to have ever lived.  
  • Aysheaia — This is an extinct genus of soft-bodied creatures that lived in North America during the Middle Cambrian. Like the Hallucigenia, this Aysheaia was a lobopod. It had a segmented body with a pair of legs on each leg. 
  • Collinsium — This was a genus of lobopodian creatures found in Early Cambrian deposits from China. The small worm-like animal lived before the Hallucigenia, but both organisms had a similar appearance, with walking appendages and spines on their backs. 

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About the Author

Abdulmumin is a pharmacist and a top-rated content writer who can pretty much write on anything that can be researched on the internet. However, he particularly enjoys writing about animals, nature, and health. He loves animals, especially horses, and would love to have one someday.

Hallucigenia FAQs (Frequently Asked Questions) 

How big was Hallucigenia?

Hallucigenia was a small, strange-looking creature with a tubular body. It was about 0.2–2.2 inches long, with 10 pairs and up to seven conical spines. The conical spines are slightly curved, and each one is roughly 0.4 inches long.

When was the Hallucigenia alive?

The existence of Hallucigenia dates back to the Cambrian Era, about 505 million years ago. The creature evolved during the Cambrian explosion along with several other animal groups. It probably went extinct during the Cambrian-Ordovician extinction event, which occurred about 488 million years ago.

What did Hallucigenia evolve into?

Paleontologists consider the Hallucigenia a critical evolutionary branch that gave rise to many invertebrates still alive. These include velvet worms, water bears, and other groups of arthropods.

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  1. Daily Mail / JONATHAN O'CALLAGHAN FOR MAILONLINE, Available here: https://www.dailymail.co.uk/sciencetech/article-2727719/Evolutionary-misfit-WORM-Bizarre-spiked-505-million-year-old-creature-finally-given-place-Tree-Life.html
  2. Wikipedia, Available here: https://en.wikipedia.org/wiki/Hallucigenia
  3. The Verge / Arielle Duhaime-Ross, Available here: https://www.theverge.com/2015/6/24/8838169/hallucigenia-worm-fossil-nature-study-2015
  4. Earth.com / Evan Levy, Available here: https://www.earth.com/earthpedia-articles/what-the-heck-is-hallucigenia/

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