USES OF THE PIT ORGAN

The study of the use of the pit organ is difficult since mammals, like ourselves, do not possess such an organ for further study. However, there have been many suggested behavioral uses for the pit organ in pit vipers. These roles include prey acquisition, predator defense, and thermoregulation (Krochmal et al., 2004).

PREY ACQUISITION

As discussed before, pit vipers are ambush predators. They seldom hunt their prey actively. Further, they generally hunt at night in conditions where visibility is practically zero. The use of their infrared sensory mechanism is key during these times. This mechanism allows them to choose foraging sites with cool backgrounds (Bakken et al., 2007) so that their prey will contrast brightly. The ability to produce infrared images of its prey allows the pit viper to strike accurately and precisely (Van Dyke et al., 2009). After striking their prey, the infrared sensory mechanism will aid the pit viper in tracking its prey (Bakken et al., 2007).

(Predicted images of endothermic prey contrasting with a cooler background--Images courtesy of George Bakken)

This video shows the use of infrared imaging in a rattlesnake preparing to ambush its prey.

PREDATOR DEFENSE

A study conducted by James Urban Van Dyke has related the use of the pit organs in pit vipers to defensive behavior. In this study, blinded copperheads vibrated their tails violently when warm, scentless objects were placed in front of them (Van Dyke et al., 2010). Tail vibrations are a sign that the snake feels threatened. The conjunction of tail vibration and striking can be seen as a defensive maneuver. This defensive behavior shows that the pit organs are beneficial as pit vipers are more likely to confront a predator head on rather than flee (Roelke et al., 2007).

THERMOREGULATION

The possession of facial pits allows pit vipers to thermoregulate in habitats that exhibit diverse thermal gradients. The ability to thermally contrast the thermal radiation produced by the background against objects in its habitat allows the pit viper to find refuge in a cooler location (Bakken et al., 2007). This mechanism could potentially be used in den selection as well (Krochmal et al., 2004).