When they are fully developed, manatees weigh 800 to 1,200 kilos (360-545 kilograms) and attain 10 feet (3 meters) in duration. The largest of the species can increase to be up to 3,500 kilos (1,590 kilograms) and thirteen feet (4 meters) in duration. Their tough skin is wrinkled, and their dimension is no joke: They're about 4 to 4.5 toes (1.2 to 1.4 meters) lengthy at delivery and average 60-70 lbs (27 to 32 kilograms). Friends die.