ИСТИНА

Morphological diversity of BTO in Anseriformes implies the size of the receptor fields, the number and size of receptor units in the upper and lower nails, and the BTO asymmetry as a whole. Swans have the largest receptor fields and units, more than 200 sensillar ones in the maxilla and about 100 asensillar in the mandible.The average density of the lower units is 3 per mm2 in swans, 6.7 in geese, from 2 (Eider) to 7 (Smew) in sea ducks, 7 in pochards, and 13.7 (8-25) in dabbling ducks. The BTO asymmetry increases from Anserini (K=1.7) to Anatini (K=7.0). It correlates with the number of BTO units in the mandible (r=0.66; p<0.01).