Which frogs are cited in Jurassic Park as able to change sex?

Jurassic Park cites West African frogs as frogs able to change sex. Dr. Ian Malcolm uses the example to explain how the park’s genetically engineered dinosaurs could reproduce despite being created as females.

The film’s geneticists fill gaps in dinosaur DNA with amphibian DNA. Malcolm argues that this makes the animals biologically unpredictable: some frogs can change sex in single-sex environments, so the park’s supposedly female dinosaurs may not remain female. The discovery of dinosaur eggs outside the controlled hatchery confirms his warning.

The reference is specifically to West African frogs, not to tree frogs, American bullfrogs, or poison dart frogs. The idea reflects real biological phenomena, although “changing sex” can simplify several different processes in amphibians. Some frog species can alter reproductive sex under particular biological or environmental conditions; the film adapts that science for its fictional cloning premise.

This detail is central to the movie’s famous line that “life finds a way.” The dinosaurs’ ability to reproduce is not planned by InGen, but it follows from the unintended consequences of using frog DNA to repair incomplete dinosaur genomes.