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).
The giant manta is commonly found offshore, while the reef manta, as its name suggests, is found inshore near coral and rocky reefs. Manta rays live in the open ocean, swimming continuously through the water column instead of resting on the sea floor like other rays. Although much of their time is spent near the surface, they have been known to dive to depths of 100 feet.