thermococcales thermococcales in taxonomy, the thermococcales are an order of microbes within the thermococci. the species within the thermococcales are used in laboratories as model organisms. all these species are strict anaerobes and can ferment sugars as sources of carbon, but they also need elemental sulfur. thermococcales thermococcales scientific classification domain: archaea kingdom: euryarchaeota phylum: euryarchaeota class: thermococci order: thermococcaleszillig et al. 1988 family thermococcaceae