Infrared sensing in snakes

The pit organ and the Labialgruben are sensory organs that serve different snakes for detecting infrared radiation. In the course of evolution, some taxa of snakes have very well specialized in the detection of warm-blooded mammals. This sense allows the snakes to go even in total darkness on the hunt.

The pit organ

The pit organ of snakes is to the left and right of the front upper jaw between nostrils and eyes in a recess in which a thin membrane located. It acts as an antenna for infrared radiation (infrared receptor) and is well supplied with blood. Behind the membrane is an air-filled chamber.

The membrane is associated with numerous sensory nerve fibers of the trigeminal nerve, are the signals from the pit organ ( by "thermal radiation" ) to the midbrain roof ( tectum of midbrain ) forwards and processed there. The infrared receptors on the membrane are part of the TRP receptor family. These receptors are ion channels and widespread in the nervous system of vertebrates as a thermal receptor. The TRP receptors of snakes with pit organ respond by all ion channels in vertebrates most sensitive to temperature fluctuations.

With the pit body temperature changes from 0,003 ° C at the membrane can be detected.

For a sub-family of vipers, the pit vipers, the pit organ is eponymous. The pit -like arrangement of the receptors allows pit vipers to see a very precise spatial infrared image. In addition, the pit vipers have the ability to link this infrared image with the visual image. This helps these otters at night at a very precise spatial image. The pit organ is located on each side of the head between the eye and mouth.

The Labialgruben

The Labialgruben have a highly perfused ground on which are the infrared receptors. These pits the snakes can temperature differences down to 0.026 ° C register.

In the family of giant snakes have the species of the subfamily of the Pythons (except the members of the genus Aspidites ) and some genera of the subfamily of boa snakes these pits. They are arranged in an imbricated row along the upper and lower lip. The Labialgruben have arisen evolutionarily independent of the pit organs of pit vipers and not quite as effective as this one.