thermococcaceae thermococcaceae in taxonomy, the thermococcaceae are a family of the thermococcales. almost all species within the three genera of thermococcaceae were isolated from hydrothermal vents in the ocean. all are strictly anaerobes. thermococcaceae scientific classification domain: archaea kingdom: euryarchaeota phylum: euryarchaeota class: thermococci order: thermococcales family: thermococcaceae zillig et al. 1988 genera palaeococcus pyrococcus thermococcus phylogeny 16s rrna-based ltp_12_2021 by the all-species living tree project. gtdb 07-rs207 by genome taxonomy database. palaeococcus thermococcus species-group 2 pyrococcus thermococcus palaeococcus takai et al. 2000 thermococcus species-group 2 thermococcus species-group 3 pyrococcus fiala & stetter 1986 thermococcus zillig 1983