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 largest living ray and one of the largest of all elasmobranchs , the giant manta ray (Manta birostris) is a stunning and graceful member of the devil ray family (Mobulidae). This giant fish is notable for its sheer size, with anecdotal reports of individuals measuring up to 9.1 metres across .