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).
1 The giant manta ray is the largest ray species in the world. 2  The giant manta ray has the largest brain of all the worldâs fishes, and much remains to be discovered about its intelligence and social interactions.  Despite its massive size, the giant manta ray feeds on some of the smallest organisms in the ocean.