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).
Description & Behavior. Giant mantas, Manta birostris (Walbaum, 1792), aka Atlantic mantas, devil rays, mantas and Pacific manta rays, are the largest of the rays and are closely related to sharks. These harmless, majestic creatures have short tails and no stinging spines. They are very acrobatic and are able to leap high from the water.