He brought attention to the world's declining sea turtle populations due to over-exploitation and habitat loss.
He also authored the Handbook of Turtles, and with Coleman Jett Goin, Guide to the Reptiles, Amphibians and Freshwater Fishes of Florida.
Carr became a bit of a legend at UF, and students vied with one another to take his Community Ecology course in which they were involved in several major and minor field trips around northern Florida and southern Georgia.
Listening to Carr talk about the Sand Pine scrub near Ocala or his comments as he guided students through the Okefenokee Swamp in canoes was considered a great privilege.
[citation needed] Carr was also known for his efforts in conservation, especially for sea turtles, helping convince Costa Rica to establish Tortuguero National Park in 1975.
He was a co-founder of the Caribbean Conservation Corporation, which helps to save and monitor sea turtles in Tortuguero, Costa Rica.
In 1952 the National Academy of Sciences awarded Carr the Daniel Giraud Elliot Medal.