Original sentence: Generally, manatees have a mean mass of 400-550 kg (900-1200 lb), and mean length of 2.8-3.0 m (9-10 ft), with maximums of 3.6 meters and 1,775 kg seen (the females tend to be larger and heavier).However, they have been known to swim at up to 30 km/h (8 m/s; 20 miles per hour) in short bursts.On average, most manatees swim at about 5 km/h to 8 km/h (1.4 m/s to 2.2 m/s; 3 to 5 miles per hour).When born, baby manatees have an average mass of 30 kg
Edited sentence: Generally, manatees have a mean mass of , and mean length of , with maximums of  and  seen (the females tend to be larger and heavier).However, they have been known to swim at up to  in short bursts.On average, most manatees swim at about.When born, baby manatees have an average mass of