Produced by the Population Genetics and Evolution class, Furman University

The Cambrian: Aysheaia
Aysheaia is genus of extinct worm-like organisms that lived during the Cambrian Period 570 to 500 mya (Smithsonian Institution 2010). Most fossilized specimens come from either the Burgess Shale Formation of British Columbia or the Wheeler Formation in Utah (HVNMH 2010). Members of Aysheaia have cylindrical, segmented bodies about 1-6 cm in length, 10 pairs of spiked limbs with claws, and a ring of 6 finger-like appendages around their mouths as well as a set of 2 grasping appendages on their heads (Whittington 1978). They were probably parasites that fed off sponges, based on anatomical considerations as well as the discovery of ancient sponge remains near many Aysheaia fossils (Smithsonian Institution 2010). They were not burrowers, and their soft bodies may have left them vulnerable to predators such as arthropods. Researchers have speculated that they avoided predation by living within sponge colonies. Aysheaia is somewhat similar to both Onychophora and Tardigrada, but it is typically classified as an onychophoran or a primitive kind of "lobopod" organism from which the arthropods and tardigrades descended (Whittington 1978).

Page by Bob Mazgaj

Aysheaia specimen from the Burgess Shale. Photo credit: Living Landscape

Hooper Virtual Natural Museum of History (HVMNH). 2010. Aysheaia. Accessed 30 Jan. 2010.

Smithsonian Institution.2010.Burgess Shale:Aysheaia pedunculata (a velvet worm). Accessed 30 Jan. 2010.

Whittington HB.1978. The Lobopod Animal Aysheaia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Phil. Trans. Roy. Soc. B. 284: 165-197.