Meeting Abstract

79.6  Sunday, Jan. 6  Anatomy and infrared imaging properties of the facial pits of North and Central American Pitvipers (Viperidae: Crotalinae) COLAYORI, Samantha E*; BAKKEN, George S.; Indiana State University; Indiana State University gbakken@indstate.edu

Facial pits are specialized organs possessed by pitvipers (Viperidae: Crotalinae) that detect emitted thermal radiation. The facial pits detect emitted thermal radiation and appear to function like a pinhole camera eye. The radiation is detected by the heating of a temperature-sensitive membrane suspended with an air-space behind it. This complex 3-dimensional internal and external geometry of the pits determine the nature of the image falling on the membrane, as the opening of the pits comprises the effective pinhole aperture that defines the optical spread function for the images. Previous attempts to understand the imaging characteristics of the facial pits have assumed a simplified geometry that leaves out much of the geometric detail of the shape of the pits and arrangement of the membrane. To avoid geometric distortion due to tissue processing and embedding, we used x-ray CT scanning to obtain serial sections of fresh (frozen and thawed once) specimens of Agkistrodon piscivorus, Bothriechis schlegelii, Crotalus atrox, C. horridus atricaudatus, C. oreganus, and Sistrurus miliarius. We used these images to create 3-dimensional computer reconstructions of the facial pit and pit membrane. We analyzed these models to define the optical spread function for source objects at various distances and azimuth and elevation angles relative to the axis of the head. We use these data in the optical and heat transfer model presented at previous meetings to construct representations of what various species can �see� with the facial pits. This allows us to estimate the nature of the image formed in relation to pit geometry and examine developmental and interspecific patterns of potential functional significance.