You could be forgiven for feeling a little uneasy when entering a dark cave known to be home to snakes. As this video shows, even in complete darkness some snakes are able to launch an assault on passing prey with incredible accuracy. A new study published in the journal Matter has discovered how certain snakes can see so well in the dark by using the heat from the organisms they’re hunting. The snakes convert the difference between ambient temperature and the warm bodies of their victims into electrical signals that alert the snake to the prey's location.
Pit vipers, boa constrictors, and pythons are three such snake varieties capable of catching prey in total darkness. It's long been suspected that this skill was in some way linked to electrical activity but the exact details as to how had eluded scientists, until now.
The researchers behind this new study had previously investigated pyroelectric materials, which are able to generate a temporary voltage when they are heated or cooled. Pyroelectric materials, which are quite rare in nature, are mostly rigid and brittle but when the team successfully produced pyroelectric effects in a soft, rubbery material in a study published last year they experienced a lightbulb moment.
"We realized that there is a mystery going on in the snake world," said Pradeep Sharma of the University of Houston and corresponding author for the paper in a statement. "Some snakes can see in total darkness. It would be easily explained if the snakes had a pyroelectric material in their bodies, but they do not. We realized that the principle behind the soft material we had modeled probably explains it."
Some snakes have a small, hollow organ called a pit organ that can detect infrared radiation coming from materials, or animals, that are warmer than the air around them. Sharma and colleagues recognized that within this organ were cells that functioned like pyroelectric materials in generating small voltages in response to temperature changes. These voltages are then able to inform the snake about its surroundings, aiding it in snatching bats from the air in even the most ambitious of cave-dwelling predation attempts.
"The fact that these cells can act like a pyroelectric material, that's the missing connection to explain their vision," Sharma explained, but while their explanation holds water some questions still remain. There is an abundance of ion channels found in the cell protein TRPA1, which is seen in greater quantities in pit-organ snakes than in those without. It’s possible that these may also play a significant role in the night-vision capabilities of such snakes, but more research is needed to clarify a potential mechanism through which this is possible.
"Our mechanism is very robust and simple. It explains quite a lot," Sharma said. "At the same time, it is undeniable these channels play a role as well, and we are not yet sure of the connection."
