There are a number of creatures in the animal kingdom that can weigh a ton or more, including the southern elephant seal, the blue whale and the hippopotamus. According to About.com, the white rhinoceros and the African elephant also typically weigh at least a ton.
Of these very large animals, the blue whale is by far the heaviest, tipping the scale at an astounding 110 to 176 tons. For comparison, the second heaviest is the African elephant, weighing in at 4.5 to 7.8 tons. It takes up to 40 African elephants to weigh as much as a single blue whale.