Wiwaxia

Wiwaxia reconstruction, from http://www.coe.uga.edu/~pkeck/ediacara/pics

Locomotion

Another bottom dwelling creature, Wiwaxia crawls slowly across the mud of the sea floor. The belly of Wiwaxia is broad and soft with bands of muscle that contract to move it forward along the sea floor.

Feeding

Near the front of the animal on the ventral side there is a mouth with two rows of teeth that opens to allow a radula to extend and sweep up organic material.

Defensive Tactics

Wiwaxia has a double row of elongated spines extending upward from its back, similar to that of Hallucigenia. These spines in addition to the golden-yellow scale-like sclerites that cover the entire body are likely to be defensive tools used to protect these small creatures (ranging from 3 to 55 mm in length) from predators. The sclerites are arranged in different patterns depending on the location on the body. On the back, between the two rows of spines, the sclerites form transverse rows. On the lower sides of the body the sclerites are in bundles. The sclerites have walls of chitin and are filled with fluid. Wiwaxia probably grew by molting the sclerites regularly.

Classification

Although Wiwaxia is similar to a mollusk, it does not really fit this group because of its armor. Charles D. Walcott described the creature as polychaete annelid (a bristle worm), but Conway Morris argued that Wiwaxia’s sclerites are not like those of polychaetes and grouped Wiwaxia with other scleritome bearing animals of the Cambrian. It is still controversial as to what group Wiwaxia really belongs.

See Wiwaxia in a color reconstruction: Burgess Shale Community