Mode of life – habitat:
Tectonic plates separated and shallow waters levels started to rise, especially towards the end of the Cambrian when the ice caps melted. Calcium and phosphate increased, along with an increase in oxygen levels from sunlight, where it brought light to the shallow oceans. The oceans were a mixed ground ecosystem due to the increase in photosynthesis from sunlight.
Anomalocaris were present 530 million year ago, from early to late Cambrian, where they were more abundant in the mid-Cambrian era. They lived for 250 million years.
They were a cosmopolitan distribution, meaning that they extended its habitat all over the world from Canada, China, Utah and Australia. They dispersed from sub polar to tropical latitudes.
They were aquatic animals that lived in the benthic zone (bathyuriscus-elrathina zone) at around 1200m in depth and were the most dominating top predator animals.
Life habits were known as the nektobentic or nektonic where they are able to swim just below the surface and to interact with the seafloor (www.iupui.edu)
Its streamlined flexible movement to the body is ideal for swimming, where the flaps propel the animal through the water and that the gills are used for ventilation from the oxygenated water.
The flaps act as a single fin to maximise it stability, giving an optimal swimming motion. A pair of 11 flexible overlapping flaps on the right and left hand side of the body produces a wave-like movement to help to propel the animal forward.
Its pair of fan shaped posterior tail with 3 blades in each pair was used for propulsion.
The swimming behaviour of the anomalocaris in water is done by performing hydrodynamic calculations, this is done by means of swimming in motion along the surface and using particles movement by waving its flaps (Y Usami, 2006, Journal of theoretical biology).
Increase in flap width leads to an increase in speed and energy loss, which gives an efficient way in its movement. Its speed is 0.4m/s when their flaps are 6m in width and its max speeds of 0.6m/s if flaps are up to 7m in width.
3D diagram showing increase in swimming speed and energy loss. data points bracketed numbers shows width of each flap, for example the first bracket shows a flap width of 3m to a flap rate of 7m. Dashed lines shows a proportional line of constant v/E. astrix indicates the largest value in v/E. (Y. Usami, 2006, Journal of Theoretical Biology showing Hydrodynamic calculations)
Anomalocaris was a top carnivorous predator that ate soft and hard bodied prey. Their diet was mostly trilobites.
Two large compound non-mineralised eyes containing 30,000 hexagonal packed lenses per eye which shows that they were highly mobile visual predators in catching its prey. Contained flexible eye stalks that swivelled forward, these were used for to check its prey ahead. A pair of appendage limbs was used to filter water and sediment on the seafloor in order to catch, with spines that can grasp it prey. It would catch its prey by thrusting its head and appendages forward at a 180 degrees. It would then feed by grabbing one end of their prey in their jaws towards its squared tooth lined mouth, while using their appendages to rock the other end of the animal back and forth in order to startle it and causing the exoskeleton to rupture. Sucking in the aid of indigestion is a means of feeding soft bodied animals. Mid gut would be used as food storage. Shows evidence that they ate trilobites due to the presence of faecal pellets. Records show that teeth type plate marks matches the rounded healed bite marks made on the right hand side of the trilobite that indicate unsuccessful predation, http://www.newark.osu.edu. It may not have engaged in cooperative hunting, but May been attracted to the commotion caused by the activities other anomalocaris.
Y. Usami, 2006. Journal of Theoretical Biology, Thernodynamic simulation, page 13.
Daley, A.C, 2010. Anomalocaridids, current biology, vol 23, issue 19, page 860-861
Briggs, D.E, 1994. Giant Preditors, American association for the advancement of Science from the Cambrian of China, page 1283
Roy, P.V and Briggs, D.E , 2011. A giant Ordovician Anomalocaridid, nature page 510-513
Gould, S.J 1989. A Wonderful life the Burgess Shale and the nature of history, page 194-206
Morris, S. 1998. The crucible of creation the Burgess shale and the rise of animals, Oxford University Press. Page 56-59