And nature made a calorimeter....

[dmendesf]

https://blogs.scientificamerican.com/artful-amoeba/how-a-half-inch-beetle-finds-fires-80-miles-away/

[Vipitis]

that is fantastic. I have theorized about this happening for some time. The eye has evolved on different lifeforms analogous. And there are sensor cells for heat in our skin everywhere. It only needs the evolutionary drive to concentrate those sensor cells in a cavity. I think that the natural transmission spectrum of water had held such a development back. Because water was the key to concentrating visual lights on early retina photoreceptors.
The sensitivity stated in the article is crazy however. I wonder if this design can be copied for a new senor design.

[Fraser]

Snakes use thermal ‘imaging’ of a sort to detect prey.

https://en.m.wikipedia.org/wiki/Infrared_sensing_in_snakes

Fraser

[Vipitis]

I had seen some videos about snakes finding prey in a dark room. However I never read deeper into it. From the linked article and used sources it appears to be a researched topic. One source (http://jeb.biologists.org/content/210/16/2801.full) even goes as far as measuring the physical shape and performance of a snakes sensory organ and modeling it using a thermal camera and some digital trickery. The snake uses a design similar to bolometer, which is different to the bug above. But optics are based on the cavity pinhole system. No fluid in the body will work for thermal infrared like water does for visible light. Therefore the evolutionary step is comparable to snails for visible light. I don't see a way to go further with the found sensory mechanism.

[Bud]

I've seen a documentary about snakes hinging lizards and if a lizard did not move while a snake was passing by, the snake did not see the lizard. Does not sound like thermal sensory to me, at least detecting movement seems to have to do something with it.

[Vipitis]

Lizards are ectotherm meaning their body temperature is controlled from outside. That's why you see them sitting in the sun for example.
In the article there is lots of speculation bout the function of said heat sensing features. There needs to be more research done for the question of why the feature developed and which selection factors it supported. Finding pray isn't the only useful thing, navigating to a cool place might also be a cause. Snake venom causes increased blood flow through the skin of the victim - which gives it a better heat signature, it also forces them to leave a trail of warm urine that the predator can track by smell (and/or heat sensing).

[Fraser]

Also, it is only Boas, Pythons and Pit Vipers that have these thermal sensors. Other snakes have to rely upon vision and tasting/smelling the air. Many hunting animals react to visible movement so an animal staying very still can sometimes avoid detection. Staying still as a large snake approaches you must be very challenging !

Fraser