Researchers have long been curious about how iguanas ended up in Fiji, a remote island group in the South Pacific. Most iguanas are found in the Americas, which are thousands of miles away. Some believed that iguanas may have traveled through Asia or Australia before Fiji shifted farther away due to geological changes. However, new research suggests that iguanas likely crossed the ocean by floating on rafts of vegetation. This journey would have been over 5,000 miles (8,000 kilometers)—the longest recorded ocean trip by a land-dwelling animal.

Genetic studies of 14 iguana species from the Americas, the Caribbean, and Fiji reveal that Fijian iguanas are closely related to North American desert iguanas. Researchers believe these two groups split about 31 million years ago, supporting the idea that they traveled by sea. Using genetic data, iguana distribution patterns, and environmental factors, researchers created a model that showed ocean drifting was the most likely explanation. Desert iguanas’ ability to survive with little water and eat plants may have helped them complete the journey. Understanding their origins is important for protecting native Fijian iguanas, which face threats from invasive species like green iguanas.