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12 animals with the longest gestation period

Rhino

Photo: mdpettit/Flickr

6 of 14

Rhinos

It might not come as a surprise that rhinos — because of their sheer size — are next on the list with a gestation period of about 450 days. This long gestation period is also an obstacle to replenishing the population. All five species of rhinoceros are endangered or considered vulnerable, and three out of the five are considered critically endangered.