A tiny, ugly scientific marvel: Olaf the IVF toad brings hope to at-risk species

Amphibians are at the forefront of a battle against extinction - but they're not the only ones benefiting from 'frozen zoos'

Olaf grasps Diane Barber's gloved hands with his sticky, four-fingered legs. His skin is bumpy and moist, the colour of pebbles at the bottom of a river when dappled sun hits them. Olaf's eyes are deep amber. His body lifts and falls with each breath. "The males get really pretty," says Barber, ectotherms curator at Fort Worth zoo in Texas. "Sometimes they'll turn a solid yellow when they're in breeding form."

In some ways, this toad shouldn't exist at all. He is the progeny of an egg from a captive mother and sperm from a wild father - a hybrid from parents who were both dead. Olaf is not the first amphibian to be born via IVF - that has been happening for years - but he is the first to be born from sperm that was frozen and thawed.