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.
http://wiki.answers.com/Q/How_long_is_a_black_rhino_pregnant_for. A Black Rhino is pregnant usually between 419 and 478 days, or 15 to 16 months. The mother will give birth to a single calf, weighing in on average 35 to 50 kg, (about 80 pounds). The calf will stay with it's mother anywhere from 2 to 3 yea...
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.