Produced by the Population Genetics and Evolution class, Furman University

The Cambrian: Wiwaxia
Wiwaxia was first discovered in 1899 in the Burgess Shale Formation (Waggoner and Collins 1994). The first findings only consisted of spines and broken pieces, but whole specimens were found shortly thereafter. To date, 140 specimens have been found. This organism had two rows of spines on its back which are thought to have served as protection from predators like Anomalocaris. There is evidence from the broken spines that have been found that this animal was sometimes preyed upon. The rest of its upper body was covered in small overlapping plates (known as sclerites) that were attached with a root-like structure. It also appears that Wiwaxia grew by molting their sclerites, and that they ranged from 6-50 mm in length. (Fossil Museum 2010). Their sclerites and spines are not chitinous as would be expected; they may be made of cartilage, but it is not known for certain. The ventral side of Wiwaxia was smooth like a slug, but they had no distinct head or tail region from the top view (Wikipedia 2009). They did have an anterior jaw with two rows of teeth, meaning that they were bottom feeders (Fossil Museum 2010). Some paleontologists suggest that these feeding structures resemble the radula of modern molluscs. Their intestinal tract seemed to run straight from their head to the rear, but nothing is known about their respiratory system. Wiwaxia also have no signs of eyes or tentacles, so it is inferred that they relied on smell and taste to survive (Wikipedia 2009).

Page by Lindsay Gerzel
Wiwaxia fossil and reconstruction. Photo Credit: Royal Ontario Museum

Waggoner BM, Collins AG. 1994. Cambrian: Life. University of California Museum of Paleonnotology. Accessed January 31, 2010.

Fossil Museum. 2010. Rare Wiwaxia enigmatic soft body animal fossil. Accessed January 31, 2010.

Wikipedia. 2009. Wiwaxia. Accessed January 31, 2010.