An unusual worm had enormous eyes and prominent fins. A chunky
burrowing carnivorous worm called Ottoiawas found with shelly animals still
in its gut.When reaching out from the bottom mud, it extended a muscular,
toothed mouth and swallowed its prey whole.An odd creature called Opabinia
(Fig.56) had five eyes arranged across its head, a vertical tail fin to help steer
it along the seafloor, and a grasping organ projected forward possibly used for
catching prey. Its long, hoselike front appendage bestowed upon it the name
“swimming vacuum cleaner.”
About half the Burgess Shale fauna consisted of arthropods, with fossil
remains of about 20 different arthropod possibilities that did not survive. One
giant arthropod was as much as 3 feet long.The most interesting of all Burgess
Shale arthropods because of its unusual shape is Aysheaia,an animal with a pudgy
body and stubby limbs.An extraordinary arthropod called Anomalocaris (Fig. 57),
whose name means “odd shrimp,” was possibly the biggest of the Cambrian
predators as well as the oldest-known large predator in the fossil record. This
earliest of monsters reached 6 feet in length and had a mouth surrounded by
spiked plates on the underside of the body. Up to eight rings of teeth reaching
10 inches across were arranged concentrically, leading into the mouth.
Anomalocaris propelled itself by raising and lowering a set of side flaps,
swimming in a manner similar to modern manta rays. It also had a broad tail
with a pair of long trailing spines used for steering and stability.The body was
flanked by a pair of jointed appendages apparently designed for holding and
crushing the armored plates of invertebrates. The animal appeared to be well
equipped for devouring crustaceans and is appropriately dubbed the “terror of
trilobites.” Many trilobite fossils are found with rounded chunks bitten out of
Figure 56Opabinia
had a forward-projecting
grasping organ for catching
prey.CAMBRIAN INVERTEBRATES