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).
Physical distinctions between oceanic manta ray and reef manta ray[edit] The first difference could be the size because the oceanic manta ray is bigger than the reef manta ray, 4 to 5 meters in average against 3 to 3.5 meters. However, if the observed rays are young, their size can easily bring confusion. Only the color pattern remains an effective way to distinguish them.