Johann Wilhelm Haacke (23 August 1855 – 6 December 1912) was a German zoologist born in Clenze, which is now Lower Saxony, who served as Director of the South Australian Museum in Adelaide from 1882 to 1884.
[2] In August 1884 he laid to rest an old mystery about echidnas, proving they are oviparous not viviparous,[3] with a specimen sent to the museum by a naturalist on Kangaroo Island.
[7] He served as zoologist with the 1885 Geographical Society of Australasia's expedition to the Fly River, Papua New Guinea.
[8] In June 1886 he announced his imminent departure for Europe, and was invited by a large deputation of German settlers to represent them at an Allgemeiner Deutscher Kongress to be held in Berlin that September but declined, and left South Australia around July 1886 without fanfare.
Haacke is remembered for research of oviparity in monotremes, and studies involving the morphology of jellyfish and corals.
[10] Haacke believed that cells consist of individuals called gemmaria that operate as hereditary units.