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).
Note: Giant Manta Rays are commonly referred to as the Atlantic manta ray. However some specialists recognize two other species of manta, known as the lesser devil rays, Manta hamiltoni (Pacific manta ray) and Manta alfredi (Prince Alfred's manta ray).