The eel-like frilled shark has the longest gestation period in the animal kingdom. This shark dwells in deep waters off the coasts of South Africa and Chile, and Science Focus suggests that the intense cold of its habitat may contribute to its long, slow gestation.
The elephant holds the record for the longest gestation period of any mammal at 22 months. This exceeds even the gestation period of whales, which ranges from 10 to 18 months, depending on the species. The record for the shortest gestation of any mammal belongs to the Virginia opossum, which gives birth after a mere 12 days, after which the offspring spends several months living in the mother's pouch.