Gundlach was born in Marburg where his father was a professor of physics. His father died young and he then followed his mother's suggestion to study theology. He however quit studies and joined the university museum and shifted to study zoology, thanks to Maurice Herold, with a tuition waiver on account of his being the son of a faculty member. He had had an interest in animals even at a young age. He helped his brother in taxidermy and preservation of biology specimens. An early accident with a gun injured his nose and he lost his sense of smell and taste. He graduated from
Marburg University and received a master of arts in 1837 and Doctor of Philosophy in 1838. In 1838 he planned a visit to Surinam, where he had a Dutch army physician friend Jules Hille (1812-1849), with travel support from the
Verein für Naturwissenschaften Kassel. Its second director
Robert Wilhelm Bunsen (1811–1899) raised shares worth 1218 thaler from 105 subscribers. He was to send back natural history specimens in return in repayment. In 1839, he left Europe to visit Surinam but was he finished most of his collections by the time he reached the
Caribbean island of
Cuba. The specimens he collected on his first expedition were sold by Eduard Sezekorn (1796–1869) to cover the money raised. His friend in Surinam had died in the meantime. He then lived in Cuba with help from the local landowners. He established a local museum in 1846 near Cárdenas on a farm called El Refugio. The collections he set up attracted a large number of visitors. He made collecting trips, sending specimens to Europe from there. In 1864 he moved this museum to the sugar farm of the Simón de Cárdenas family. During a short trip to
Puerto Rico, at the request of Jesuit fathers to offer assistance in the creation of a zoological collection in 1868, when revolutionary activities were beginning in Cuba as well as Puerto Rico, he met with don
Tomás Blanco y González (1840–1892), according to naturalist Dr.
Agustín Stahl. In 1867 his collections were exhibited in Paris at the Exposition Universelle and he received a silver medal. A friend of
Carl Wilhelm Leopold Krug, who served as German Vice Consul in
Mayagüez, Puerto Rico and who paid for some of Gundlach's travels, he visited Puerto Rico in 1873, leaving Havana on 4 June 1873 on the ship Manuela, arriving in Mayagüez on 13 June and staying in Puerto Rico for approximately six months. During that trip, Gundlach contributed to the founding of the
Civil Institute for Secondary Learning or "Instituto Civil de Segunda Enseñanza". This institute was closed several months later, in keeping with the Spanish government's policy expressed to the bishops of
Santiago de Cuba and of
San Juan of limiting the opportunities for higher learning on both islands. He subsequently travelled from Havana to Puerto Rico's west coast aboard the "Marsella" in September 1875. He remained in Puerto Rico for approximately one year; while he was there, he changed his name from
Johannes Christoph to its Spanish equivalent,
Juan Cristóbal. He wrote
Contribucion á la Erpetologia Cubana (1880) and
Contribucion á la entomologia Cubana in 4 volumes (1881–1884). He also wrote the first major work on the birds of Cuba,
Ornitología Cubana, and his name is commemorated in the scientific names of over sixty species. His hosts went into financial distress and in 1892, he sold off his collections to the Instituto de Segunda Enseñanza de la Habana and paid the proceeds to the Cárdenas family. This also allowed a small salary with which he lived alone until his death. His collections passed into the care of the
Museo Poey in
Havana, named after Cuban intellectual Dr.
Felipe Poey y Aloy (1799–1891), upon his death in 1896. ==Legacy==