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==Postfacial vibrissae==
The postfacial vibrissae are not actively involved in tactile exploration. It has been hypothesized that they function to detect water movements, thus functioning like a mammalian version of the lateral line system found in fishes and amphibians (Reep et al., 2002). This possibility is currently being examined through behavioral psychophysics experiments involving two captive manatees at Mote Marine Laboratory. Such an ability would be useful for detecting water movements associated with conspecifics, tides, and currents. It may also function to detect energy reflected from objects as a manatee moves underwater, thereby assisting in navigating the murky water environment in which manatees spend much of their time.

Postfacial vibrissae are smaller and thinner (diameter/length ratio of ~0.01) than those on the face, and their FSCs are less extensively innervated (~30 axons/ FSC) (Reep et al., 2002). However, innervation density appears to scale with size of FSC (Reep et al., 2001), perhaps preserving a relatively constant innervation density per unit area. Considering that there are ~3300 postfacial FSCs innervated by ~30 axons/FSC, this represents a total investment of ~100,000 axons.