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).
manta rays are distinctive flattened body fish closely related to sharks many people believe that manta rays are any round and flat animal but the truth is that this is not so there are only two species of fish that receive the name of manta ray and belong to the genus manta being considered the biggest members of the ray family these are the reef manta manta alfredi and the giant manta ray manta birostris animals that exceed 3 meters wide and have the largest brains of all fish