A team of scientists have developed a robot that mimics the motion of a stingray by using the cardiac muscles from a rat mounted on a stingray-shaped skeleton. The robot, detailed in a study published in the journal Science, is a wonderfully weird hybrid of biological and mechanical engineering that could be the first step towards a new class of underwater robots.

This robot uses a single layer of muscle allowed for downward contraction to mimic movement. While live creatures have another layer of muscle to pull their wings upward, the skeleton of this robot is designed to rebound after such a contraction, simplifying the overall structure. When the muscles were stimulated with light, the combined actions allowed the robot to swim forward.

The authors of the study noted that their robot is considerably smaller than a regularly sized ray, and because of that, they can’t draw direct comparisons between the two. Although this isn't the first time engineers have taken cues from the natural world - you have burrs to thank for Velcro - this robot may help with the development of robots that can move around efficiently underwater.

Unlike other robot designs, which have been drawn from sea turtles, octopuses, dogs, and cockroaches, this type of locomotion appears to be far more efficient. The team reported that they were able keep the device moving for six days, "outperforming existing locomotive biohybrid systems in terms of speed, distance travelled and durability." Using this new style of movement, researchers were able to demonstrate that this robot could easily move underwater: using light in certain patterns, they were able to steer the robot clockwise and counterclockwise, and put it through a simple obstacle course.

This robotic stingray doesn't yet have a practical use, but it's not hard to imagine how its style of movement could be applied to any number of underwater robots. For instance, robotic drones mounted with cameras could be used for monitoring the sea floor or equipment. There's a reason engineers keep stealing from the natural world - nature has some very cool solutions.