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 are pregnant for close to two years -- more than double the time for human beings. They normally have only one calf at a time, although there have been rare multiple births.