Hahn is assumed to have been in close contact with the universally known natural scientist Jakob Sturm, and probably with his two sons. He named a spider species after Jakob: "Araneus Sturmii", now "Atea sturmi" (Hahn, 1831). His relationship with Johann Georg Wagler must have been similarly close. He also named a spider species after him: "Lÿcosa Waglerii", now "Pardosa wagleri" (Hahn, 1822). Nothing reliable is known about other contacts within the remarkably productive Nuremberg zoologist scene, nor does any proof exist that Hahn knew Franz von Paula (von) Schrank personally, a highly regarded natural scientist, to whom he dedicated the "Monograph on Spiders". The scientific value of Hahn's lifework in natural history varies. His ornithological work, for example, never had any discernible influence on this field. Hahn's work on the true bugs (Heteroptera), though, is just as important as his works on spiders (Araneae). One species of bug even carries his name: "Lopus hahni" Stål, 1860. He was also given this honour in the field of arachnology: Carl Ludwig Koch, who continued ""Die Arachniden"" after Hahn's death, called a genus after him in 1841 ("Hahnia"), on which later the name of the whole family was based – Hahniidae Bertkau, 1878.