Because the Kiwa lives so deep, there is not sufficient energy from the sun to provide food, so they harness chemical energy being released through vents in the seafloor. It is not uncommon for deep-sea creatures to create symbiotic relationships, whether its to find food easier, save energy, or to mate for life. Energy is valuable, and species often become their own miniature ecosystems.
Scientists observed the crabs "wave their claws back and forth in fluid from a methane seep, and rather than trying to capture bacteria, it appeared that [the crabs] were providing food to the bacteria already growing on their claws," something referred to as "farming."
The bacteria found on Kiwa crabs is specialized-type only found on crustaceans near deep sea vents. Before discovering "farming" behaviour, scientists had never observed a host waving symbionts in seep fluid.
In 2010 and 2011, the Kiwa crabs were brought to the surface by the submarine, Alvin, for observation. Scientists used the specimens to examine the bacteria on their claws and found the genetic code of this bacteria is most similar to bacteria found on crabs and shrimp living near hydrothermal vents.
There are many cases if symbiotic relationships in the wild, but this is the only known one that by waving the symbiont-bacteria on its claws over seep fluid can capture chemical energy as a food for themselves. The crabs use specialized appendages to scrape bacteria off their bodies to their mouths all while waving their claws near the methane to boost productivity within the bacteria.
Since the species was only discovered six years ago, and was observed in a lab last year for the first time - the possibility of other species, or more from this family is highly likely. Keep your eyes pealed - you'll be reading it here if it happens!