Square Feet. The square foot is a unit of area used in the imperial and U.S. customary measurement systems. A square measurement is the two-dimensional derivative of a linear measure, so a square foot is defined as the area of a square with sides 1 ft in length.
16 Months of Patience. The white rhino is one of the largest of all rhino species, so it's not surprising that her large stature would lead to a long gestation period of 15 to 16 months. After the gestation period, the mother gives birth to a single calf weighing around 143 pounds.
Elephants has the longest pregnancy about 22 months. The shortest is 12 days. (Didelphis marsupialis); the rare water opossum, or yapok (Chironectes minimus) of northern South America and the eastern native cat (Dasyurus viverrinus) of Australia. All three of these marsupials give birth to their young while they are still at the embryonic stage.