The most vulnerable part of any underwater robot is its propeller, which can be easily damaged on rocky terrain or get caught in submerged plant. The black ghost knifefish, a South American river species, has no such problem. An undulating fin that runs along its belly propels it throug abstacle. Keri Collins, a doctoral student at the University of bath in England, developed a robot called Gymnobot (for Gymnotiformes, a group of fish species including knifefish) using the fish as a model. The robot's flexible fin, attached to a rigid body, is tangle proof, according to laboratory test. When complete, Gymnobot will help scientists study marine life in coastal waters, where varying terrain an habitats are tricky to navigate.
