The movement of the hard drive's read/write heads over different areas of the disk when accessing fragmented files is slower, compared to accessing the entire contents of a non-fragmented file sequentially without moving the read/write heads to seek other fragments.
The dorsal fins are small and at the base of the tail. The largest mantas can reach 1,350 kg (2,980 lb). In both species the width is approximately 2.2 times the length of the body; M. birostris reaches at least 7 m (23 ft) in width while M. alfredi reaches about 5.5 m (18 ft).
When newborn, mantas weigh about 10 kg, but can reach up to 1200 - 1400 kg when adults. The largest individuals span over 6m between the tips of the pectoral fins. There is no sexual dimorphism, but females tend to be a little larger than males. The entire skeleton is cartilage, just like in sharks. Skin is rough.