Born in Scotland, Sanderson traveled widely in his youth. His father, who manufactured whisky professionally, was killed by a rhinoceros while assisting a documentary film crew in Kenya in 1925.
As a teenager, Sanderson attended Eton College, and, at 17 years old, began a yearlong trip around the world, focusing mostly on Asia. Sanderson earned a B.A. in zoology, with honors, from Cambridge University, where he later earned M.A. degrees in botany and geology.
He became famous as the most credible witness to see a Kongamato, after being attacked by a creature he described as "the Granddaddy of all bats". This encounter occurred when he had shot a fruit bat that toppled into the water. He went to retrieve his catch but was warned by his partner to duck. He described the following events:
"Then I let out a shout also and instantly bobbed down under the water, because, coming straight at me only a few feet above the water was a black thing the size of an eagle. I had only a glimpse of its face, yet that was quite sufficient, for its lower jaw hung open and bore a semicircle of pointed white teeth set about their own width apart from each other. When I emerged, it was gone. ... And just before it became too dark to see, it came again, hurtling back down the river, its teeth chattering, the air "shss-shssing" as it was cleft by the great, black, dracula-like wings."
Sanderson conducted a number of expeditions as a teenager and young man into tropical areas in the 1920s and 1930s, gaining fame for his animal collecting as well as his popular writings on nature and travel.
During World War II, Sanderson worked for British Naval Intelligence, in charge of counter-espionage against the Germans in the Caribbean, then for British Security Coordination, finally finishing out the war as a press agent in New York City. Afterwards, Sanderson made New York his home and became a naturalized U.S. citizen. In the 1960s Sanderson made his home in Warren Country in rural northwestern New Jersey, where he owned approximately 8 acres. He later lived in apartment #516 in the Whitby building on West 45th Street in Manhattan's Hell's Kitchen until his death in 1973.
In 1948 Sanderson began appearing on American radio and television, speaking as a naturalist and displaying animals. In 1951 he appeared with Patty Painter (real name: Patricia Stinnette) on the world's first regularly-scheduled color TV series, The World is Yours. This was broadcast in the CBS field-sequential color system developed by Dr. Peter C. Goldmark.
Sanderson's television appearances with animals led to what he termed his “animal business.” Initially Sanderson borrowed or rented animals from zoos in the New York metropolitan area for his TV appearances. In 1950 at a meeting of the National Speleological Society, he met 20-year-old Edgar O. ("Eddie") Schoenenberger, who by 1952 was his assistant (and ultimately partner) in his animal business. Indeed, Schoenenberger ultimately became president of the company, called Animodels, in 1956. Schoenenberger suggested that, instead of "renting" animals, they should purchase and house them, and gain some additional income by displaying them in a zoo. To accomplish this, Sanderson purchased in 1952 a 250-year-old farmhouse and 25 acres of land a short ways from the ultimate location of the zoo between the communities of Columbia and Hainesburg. He immediately commenced refurbishing and expanding this, while also moving 200 of his rarest animals to a barn nearby so he could keep close watch on them. Then, in the Spring of 1954, he established the zoo itself, "Ivan Sanderson’s Jungle Zoo" (and Laboratory), a permanent, summer, roadside facility along the Delaware River on King Cole Curve on Route 46, in the town limits of Manunka Chunk, White Township, Warren County, New Jersey. It was on land leased from King Cole's, a barbecue restaurant owned by Oscar Smith (now defunct). Sanderson also developed and deployed winter traveling exhibits of rare and unusual animals for sports shows and department stores. A fire on the night of Tuesday or early morning hours of Wednesday, February 2, 1955 destroyed his collection of 45 rare animals kept in a barn at his New Jersey home. Ivan Sanderson's Jungle Zoo was flooded out by the Delaware River during the floods caused by Hurricane Diane on August 19, 1955.
Sanderson would often travel from his New Jersey home to his New York apartment to visit friends and to appear on radio and television programs.
During the 1950s and 1960s, Sanderson was widely published in such journals of popular adventure as True, Sports Afield, and Argosy, as well as in the 1940s in general-interest publications such as the Saturday Evening Post. In the 1950s, Sanderson was a frequent guest on John Nebel's paranormal-themed radio program. He was a frequent guest on The Garry Moore Show, being one of the first recognized animal researchers on television to bring live specimens on talk shows. As his friend and fellow cryptozoologist Loren Coleman has remembered in several of Coleman's books, Sanderson's appearances often involved his discussion of cryptozoological topics. Coleman notes that Sanderson could be skeptical. In "Mysterious America," for example, Coleman documents that Sanderson discovered the 1909 "Jersey Devil" incident was an elaborate real estate hoax.
Sanderson was an early follower of Charles Fort. Later he became known for writings on topics such as cryptozoology, a word Sanderson coined in the early 1940s, with special attention to the evidence for lake monsters, sea serpents, Mokèlé-mbèmbé, giant penguins, Yeti, and Sasquatch.
Sanderson founded the Ivan T. Sanderson Foundation in August 1965 on his New Jersey property, which became the Society for the Investigation of the Unexplained (SITU) in 1967. SITU was a non-profit organization that investigated strange phenomena ignored by mainstream science.
He died of cancer at his New Jersey residence in 1973.
Sanderson was married twice. His wife Alma accompanied him in the travels discussed in Caribbean Treasure and Living Treasure.
He died of stomach cancer in New Jersey, which had become his adopted home.
Nature writing
Sanderson published three classics of nature writing: Animal Treasure, a report of an expedition to the jungles of then-British West Africa; Caribbean Treasure, an account of an expedition to Trinidad, Haiti, and Dutch Guyana (now Suriname), begun in late 1936 and ending in late 1938; and Living Treasure, an account of an expedition to Jamaica, British Honduras (now Belize) and the Yucatan.
Illustrated with Sanderson's drawings, they are well-written and humorous accounts of his scientific expeditions, and anticipate later works by writer-naturalists such as Gerald Durrell. Unlike Durrell, who collected animals for zoos, Sanderson collected animals for museums and scientific institutions, and included detailed studies of their behaviors and environments. He also killed some for study. Sanderson's behavioral observations in the animals' natural environments were invaluable: much of what was known at that time concerning "exotic" species was based solely upon the examination of dead and preserved specimens.
