Research robots reveal missing piece of marine larvae life-cycles
While consumers have been getting excited over small electronics that can help track our habits, health and other activity, scientists have been putting similar technology to work with animals. In some cases this has meant affixing tracking devices to larger critters that are otherwise difficult to follow, but tinier animals, like marine larvae, can still be too small to glue an antenna on, requiring a slightly different strategy. So rather than directly follow individual baby crabs, mussels, or clams, researchers have designed trackable robots that follow larvae groups instead. This is allowing us to find out more about the life-cycles of multitudes of creatures that were otherwise lost in the churning seas.
The robots, called Autonomous Behaving Lagrangian Explorers (ABLEs), don’t look much like the tiny creatures they’re tracking. While a zoea, or larval crab, might look like just another spiny bit of plankton, the robots following their travels are bright yellow canisters researchers compare to minions. Each robot is made of a repurposed fire extinguisher, equipped with gyroscopes, tracking electronics, and a propeller wrapped around their middle like a white, flaring skirt. With this propeller, each ABLE can move vertically through the water column, which has proven key to understand where larvae go while they’re growing up.
Sticking close to shore
For a long time, it was assumed that larvae of various species would hatch, and they be washed out into the sea with no control over where they ended up. This was slightly puzzling though, since most animals seemed to return to their points of origin as adults, apparently reversing the journey forced upon them by the ocean’s currents. Once the ABLEs started their journey, researchers realized that this was not the case, and that the larvae actually had some control over where they traveled, ensuring that they’d eventually land close to home.
The trick to their movement was to travel vertically in the water column. The larvae stayed below the water’s surface, avoiding the strongest currents that would take them further out to sea. Instead, they’d move up and down below the water to catch rides on currents that would keep them close to the coast. The robots, with their single, vertically aligned propellers, found that this cycle of movement wasn’t as hard is one might think, even for tiny, baby crustaceans. With this information, we can better manage marine environments to make sure these larvae can safely grow up in their own neighborhoods, even if we’re not able to see their every movement directly.
Source: Robot Larvae Deployed at Sea by Kat Kerlin, UC Davis
