Fish scale the surface, interacting only with the riblet tips, not causing any high-veloctiy flow in the valleys. Since this high velocity flow now only interacts with the riblet-tip, which is a very small surface area, the momentum transfer which causes drag is now much lower than before, thereby effectively reducing drag. Also, this reduces the cross-stream velocity fluctuations, which aids in momentum transfer too. The rough, sandpaper-like texture of shark and ray skin, coupled with its toughness, has led it to be valued as a source of rawhide leather, called shagreen. One of the many historical applications of shark shagreen was
The X Creatures No VHS or DVD releases were ever made. The X Creatures The X Creatures is a British documentary television series that was produced by the BBC which was broadcast from 26 August to 30 September 1998 on BBC1. It was presented by Chris Packham, and examined the possibility of the existence of mystery animals. The name of the show was a reference to the popular fictional television show "The X-Files". Each episode (there were six in all, each lasting 30 minutes) involved Chris Packham travelling to a certain place on Earth where the creature supposedly exists, and examining eye witness