Surface ultrastructure of pit organ, spectacle, and non pit organ epidermis of infrared imaging bold snakes: A scanning probe and scanning electron microscopy study

Boid snakes possess unique infrared imaging pit organs. The ultrastructure of the surfaces of these organs scatter or reflect electromagnetic radiatio n of specific wavelengths. Pit organ epidermal surfaces of hold snakes are covered with arrays of pore-like structures called micropits. In order to d etermine the dimensions of this complicated surface structure, we have perf ormed the first ultrastructural analysis on snake epidermis by high-resolut ion microscopy techniques. Using scanning probe microscopy and scanning ele ctron microscopy, we found that the epidermis of pit organ, maxillary non p it organ, spectacle, and ventral scales contain arrays of micropits. These scale surfaces also contain major surface features of overlapping plate-lik e structures. Pit organ micropits averaged 319 nm in diameter and 46 nm in depth and were spaced an average of 808 nm from each other. These micropits were significantly deeper, of greater diameter, and spaced at greater dist ances apart than those of the other scales. Plate structures of the pit org ans had a mean distance between plates of 3.5 mu m and a mean plate step he ight of 151 nm. These differences serve to strengthen the argument that arr ays of micropit and plate surface structures function as spectral filters o r anti-reflective coatings with respect to incident electromagnetic radiati on. (C) 1999 Academic Press.