Pplementary fig. S1, Supplementary Material online, and fig. 3K and L). The mechanotransducing channels best favored for vertebrate stereovilli at present are TMC channels (Morgan and BarrGillespie 2013; Pan et al. 2013), possibly associated with actin. TMCs have presumably arisen at the root of metazoan too but expanded significantly in vertebrates, probably in the wake of the two rounds of WGDs