SICB Division of Ecology and Evolution (DEE)

DEE Researchers Database Entry

George Bakken

Vision-like ablilities of rattlesnake facial pit organs
Decades of experiments have focused on how the facial pits enable rattlesnakes and other pitvipers to direct predatory strikes toward the thermal radiation emitted from warm-blooded prey. Now, work done in the laboratory of George Bakken in the Department of Ecology and Organismal Biology at Indiana State University indicates that the pit organ is, in fact, a general-purpose vision-like sense with multiple roles in snake biology. Bakken and PhD Student Aaron Krochmal (now on the faculty of the University of Houston - Downtown) tested whether western diamondback rattlesnakes could use their pit organs to detect thermal radiation from the environment and use this information to find resting sites with favorable temperatures. They found that snakes with open pits could find cool refuges from a hot environment, but lost this ability when the pits were blocked. Further studies (in collaboration with Travis LaDuc, University of Texas) tested a dozen species of pitvipers from a wide range of habitats and representing major phylogenetic nodes, and found that all could use the pit organ to locate cool refuges. They concluded that thermoregulatory use of the pit organ is an ancestral condition for all pitvipers. Because thermal radiation signals from the environment are stronger than those from prey items, thermoregulation may in fact have driven the early evolution of the pit organ. (Journal of Experimental Biology 206: 2539-2545 and 207: 4231-4238.) (In the picture, Aaron Krochmal and George Bakken prepare to block the pit organs of a western rattlesnake with tiny Styrofoam beads and aluminum foil.)