This may only in part be explained by the lowest coding coverage of all archaeal genomes, 73.6% (compared to 89.2% for group I methanogens; Table 7.2), the longest average ORF size, 925bp (compared to 804bp for extreme halophiles; Table 7.3), and unusually long intergenic regions (on average 341bp in M. acetivorans versus 122bp in A. fulgidus).