Anomalocaris
Anomalocaris is thought to have been a
predator. It propelled itself through the water by undulating the flexible lobes
on the sides of its body. Each lobe sloped below the one more
posterior to it, and this overlapping allowed the lobes on each side of
the body to act as a single "fin", maximising the swimming efficiency. The
construction of a remote-controlled model showed this mode of swimming to be
intrinsically stable, meaning that Anomalocaris need not have had a complex
brain to cope with balancing while swimming. The lateral lobes overlapped; The
widest part of the body was on the third to fifth lobe; it narrowed towards it
tail, and had at least 11 lobes in total. The more posterior lobes are
difficult to discriminate, making a total count slightly difficult to reach.
Anomalocaris had a large head, a single pair of large, possibly compound eyes,
and an unusual, disk-like mouth. The mouth was composed of 32 overlapping
plates, four large and 28 small, resembling a pineapple ring with the center
replaced by a series of serrated prongs. The mouth could constrict to
crush prey, but never completely close, and the tooth-like prongs continued down
the walls of the gullet. Two large 'arms' (up to seven inches in length when
extended) with barb-like spikes were positioned in front of the mouth. The tail
was large and fan-shaped, and along with undulations of the lobes, was probably
used to propel the creature through Cambrian waters. Stacked lamella of
what were probably gills attached to the top of each lobe.
For the time in which it lived Anomalocaris was a truly gigantic creature,
reaching lengths of up to one meter.
