This robot can also dive and return to the surface. Faster flaps generate stronger downward waves that push the robot upwards, and slower flaps generate weaker upward waves that allow the robot to proceed further downwards. (A real manta ray sinks when it slows down.) It also proved possible to extract the payload from the bottom of the tank and raise it to the surface.
eat on the spot
Manta rays are essentially giant moving water purifiers, so MIT researchers look to them and other mobula rays (a group that includes mantas and devil rays) for inspiration when considering potential improvements to industrial water filters. I paid attention.
Manta rays swim and feed with their mouths open. At the bottom of each side of a manta’s mouth is a structure called a mouth plate, which looks like an air conditioner on a dashboard. When water enters the mouth, plankton particles that are too large to pass through the plates bounce further into the manta’s body cavity and eventually reach the stomach. The gills absorb oxygen from the gushing water, allowing the manta to breathe.
The MIT team was particularly interested in the mobula ray because this animal takes in water fast enough to breathe while maintaining a highly selective structure that prevents most plankton from escaping into the water. This is because we believe that we have achieved the ideal balance. To create a filter that looked as similar to the Mobula ray as possible, the team 3D printed plates and glued them together to create narrow openings in between. Particles that do not pass through flow away into a waste container instead.
As I pumped slowly, water and small particles flowed out of the filter. Increasing the speed of the pump created a vortex of water at each opening, allowing water to pass through, but not particles. The research team realized that this is why mobula rays are such successful filter feeders. They need to know the right speed to swim so they can filter the optimal amount of plankton into their mouths while breathing.
The team believes that by incorporating vortex actions, they can “enhance traditional designs.” [industrial] filter,” they say in one article. study Recently published in PNAS.
Manta rays may look like aliens, but it’s downright science fiction how they use physics to their advantage, from powerful swimming to efficient (and simultaneous) eating and breathing. Not. Sometimes nature delivers with the most ingenious technological upgrades.
Science Advances, 2024. DOI: 10.1126/sciadv.adq4222
PNAS, 2024. DOI: 10.1073/pnas.241001812
