Over 5100 bacterial viruses have been examined in the electron microscope s
ince 1959. About 4950 phages (96%) are tailed and only 186 phages (3.6%), a
re cubic, filamentous, or pleomorphic. Phages belong to 13 virus families a
nd occur in over 140 bacterial genera. Phages are listed by morphotypes and
host genera. Siphoviridae or phages with long, noncontractile tails compri
se 61% of tailed phages. The distribution of phages in different bacterial
phylogenetic divisions is shown.