Kiwa hirsuta was collected in March 2005 from vents on the Pacific-Antarctic Ridge and described later that year in a new family, Kiwaidae. Its most obvious feature is the mass of filamentous setae covering the chelipeds and legs, colonised by bacteria that fix carbon using chemical energy from vent fluids rather than sunlight.
The strongest evidence for farming comes from a relative. Kiwa puravida, described from a Costa Rican methane seep, has been observed rhythmically waving its claws in the flow above the seep. The movement is interpreted as stirring the water to keep sulphide and oxygen supplied to the bacteria, and the crabs then scrape the setae with comb-like mouthparts and eat the harvest. Isotope and lipid analyses of the crabs are consistent with a diet dominated by these bacteria.
Some caution belongs on the original species. Direct waving behaviour and dietary analysis are best documented for K. puravida, and how far K. hirsuta feeds the same way is inferred from its anatomy rather than observed. The genus is now known from several vent and seep systems, including a Southern Ocean species that crowds around vents in extreme densities.