Modes of life of arthropods from the Burgess Shale, British Columbia

The modes of life of twenty three species of arthropods from the Shale are reviewed, with special reference to locomotion and feeding. Six groups are recognised, predatory and scavenging benthos, deposit-feeding benthos, scavenging and possibly predatory nektobenthos, deposit-feeding and scavenging nektobenthos, nektonic filter-feeders, and a miscellaneous sixth group that includes a questionable example of parasitism and a species that doubtfully grazed on algae. These animals had but limited powers of walking, digging, raking or swimming. Within these limitations a range of morphological adaptations and modes of feeding had been evolved, by Middle Cambrian time, a range comparable to that found in Recent marine forms. Arthropods in the Shale dominated, in numbers of individuals and possibly in biomass, a fauna dwelling above, on and in a muddy substrate at a depth of about 100 m.