 Although the genus was first described in 1832 by Johann Georg Wagler the four species in the genus were until 2005 retained in the larger genus "Sterna", the genus that holds most terns.Three of the four species are tropical, and one has a sub-polar breeding range.The sooty tern has a pan-tropical distribution; the bridled tern also breeds across the Tropical Atlantic and Indian Ocean but in the central Pacific it is replaced by the spectacled tern.