Biota - Lifeforms

Cambrian animals have more potential for preservation than soft-bodied parts and represent the beginning of a diverse fossil record.

The Cambrian photosynthetic organisms that were the main food of animals were all single-celled organisms. These organisms included a variety of prokaryotic and eukaryotic bacteria and algae.

• A new calcareous benthic biota dominated by blue-green algae emerged.
  
• Oncoids, small marble or biscuit-shaped structures stacked concentrically, have also formed.
  
• Acritarchs are common in many marine rock types and are thought to have the potential to improve the zoning of
  
• Lower Cambrian rocks. However, their microscopic size makes them difficult to study.
  

Fauna

Calcifying archaea, an extinct group of sponges thought to have contributed to the formation of the first coral reefs, were the first skeletal metazoans to diversify rapidly and develop modular growth habits.

Brachiopods also appeared, but they were less diverse.

Arthropods were the first animals to develop legs, and characteristic trace fossils indicate their presence.

Other trace fossils indicate a marked increase in abundance and diversity, with expanded behavioral patterns reflecting increased mobility, the ability to invade sediments, and new foraging strategies.


Cambrian biota is known to have been restricted to marine environments. At least 11 extant fauna

• Annelida
  
• Arthropoda,
  
• Brachiopoda
  
• Chordata
  
• Ctenophora
  
• Echinodermata
  
• Hemichordata
  
• Mollusca
  
• Onychophora
  
• Porifera  
  
• Priapulida
  

Fossils from the Burgess Shale have been used to show the existence of complex communities that, like many modern communities, varied in habits, structure and adaptations.

The genus Anomalocaris was the largest marine predator of the Cambrian.

The most famous invertebrates of the Burgess Shale belong to the genus Anomalocaris. This organism was the largest marine predator of the Cambrian. Anomalocaris was the largest predator that swam in Cambrian seas and had a unique mouth structure consisting of circularly arranged armored plates with huge flexible appendages that could capture and move its prey.

Anomalocaris' relatives include the strange Opabinia, which had a five-eyed arthropod-like body and an elongated mammal-like structure with a pair of claws protruding forward from the head. Opabinia is thought to move along the seafloor, stirring up sediment with its flexible udders and catching hidden prey with its outstretched claws.