Kingdom Animalia
Phylum Arthropoda/Onychophora
Class Xenusia
Order Scleronychophora
Family Hallucigeniidae
Genus Hallucigenia
1st Species Hallucigenia sparsa
2nd Species Hallucigenia fortis
3rd Species Hallucigenia hongmeia
Other attributes
Time Range 521-505 mya
Location Canada, China
Name Meaning Animal from a dream
Physical Dimensions 3.5 centimeters long
Dietary Classification Detritivore

Hallucigenia is a hallucigeniid scleronychophoran xenusiid arthropod from the Cambrian Series 2-3 of Canada and China. It was named in 1977 by Simon Conway Morris. From the moment it was discovered, it has had a long history of confusing paleontologists, and it is commonly thought to be a onychophoran worm, although some people may say that it is an arthropod.


Hallucigenia was a unique invertebrate. It had a long, slender body, 7 pairs of walking legs (with each leg ending in a claw-like structure), a worm-like head with big black eyes and a semi-circular mouth internally surrounded by small teeth, and a series of protective spines running down its back. Its body would have been covered in smooth skin.


Hallucigenia was a detritivore, sucking up organic matter. Its circular mouth and small teeth would be used to pick up small pieces of detritus of the floor, right before proceeding to grind them up with the teeth in its throat and pass them down to its gut.


Hallucigenia has had a very long and strange history. When it was discovered, people had thought that the spines on its back were used for walking and the legs were just tentacles on it back. However, another discovery had proposed that the spines were actually on its back, and the supposed tentacles were the actual walking legs. As well as this, it was once thought to have an eyeless, blob-like head; however, the most recent study (involving the most recent fossil and an electron microscope) revealed that it had a worm-like head with big black eyes and a semi-circular mouth (which was described as cleverly grinning at the paleontologists at all the secrets it had been hiding).

Community content is available under CC-BY-SA unless otherwise noted.