Night On Earth: Uncovering the Infrared Spectrum of Animals

[anorlunda]

I've been watching an interesting nature program on Netflix called Night On Earth. The film was all taken at night using low light and infrared cameras. I was surprised how many animals and insects see well at night.

It makes me curious.

• Do we know how much of the infrared spectrum different animals can see?
• Choose a specific species; how do we scientifically find out what range of the spectrum that species can see?

 

[BillTre]

Pit Vipers (such as rattlesnakes) have IR sensitive pits on their noses.
Unlike how a photoreceptor works (absorption of a photon causing photochemical changes in a molecule which interacts with membrane proteins, affecting the membrane potential), the Pit organ is like a low resolution pinhole camera, but transduction (environmental condition --> neural signal) works by affecting a temperature sensitive channel protein, affecting membrane potential. These receptors and the sensory cells they resided in, are situated, in the pit organ, so they are very temperature sensitive to heat from the environment.

There apparently other IR sensitive animals:
Vampire bats have heat sensors in their weird shaped noses.
This also seems to work through a temperature sensitive membrane channel protein, like the pit viper, but presumably, independently derived. Both involve the TRVP1 channel (Capsaicin receptor).
Perhaps the channel's evolutionary precursor was involved in the body's temperature sensing mechanisms.

There are IR sensitive insects, as well as some fish:

Other organisms that have thermoreceptive organs are pythons (family Pythonidae), some boas (family Boidae), the Common Vampire Bat (Desmodus rotundus), a variety of jewel beetles (Melanophila acuminata),[38] darkly pigmented butterflies (Pachliopta aristolochiae and https://en.wikipedia.org/w/index.php?title=Troides_rhadamantus_plateni&action=edit&redlink=1), and possibly blood-sucking bugs (Triatoma infestans).[39]

Some fungi like Venturia inaequalis require near-infrared light for ejection[40]

Although near-infrared vision (780–1000 nm) has long been deemed impossible due to noise in visual pigments,[41] sensation of near-infrared light was reported in the common carp and in three cichlid species.[41][42][43][44][45] Fish use NIR to capture prey[41] and for phototactic swimming orientation.[45] NIR sensation in fish may be relevant under poor lighting conditions during twilight[41] and in turbid surface waters.[45]

The IR wavelengths that transmit through the environment (air or water), will affect what biological sensors sensors can detect. There would be no selective reason to evolve sensitivity in other wavelengths. But it might exist as a by product of the detection mechanism. I don't know what specific wavelengths they detect, but there are possible approachs:
use a behavior response to signal awareness of a sensory signal.
use a neural physiological assay (sensory fiber response) when exposed to different stimuli (the nerves and sensory organs in snakes and bats are well known).

Animals can also get around in the dark using other distance sensing capabilities.
Bats have active sonar, which works very well and is very sophisticated.
Owls have a very sensitive directional hearing sense, which they can use to find mice in the dark, based in the noises the mouse makes.

In the water, many fish are electroreceptive, but knife fish are actively electrosensitive fish which can sense their environment, detect prey, communicate with con-specifics, change frequencies they transmit at to avoid interfering with frequencies other fish. Electric eels are related to this fish.
These guys can cruise around at night or in murky waters with a very short visibility distance.
Many other fish are passively electroreceptive. They listen, but do not broadcast.
Shark, rays as well as lots of bony fish can do this.

When there is an opportunnity for an organism to gain a selective advantage by evolving a way to "see in the dark", they can opportunistically make whatever kind of a system they can cobble together from what's available (molecularly speaking). Thus, there are many solutions to the problem, but not usually capable beyond what is needed in it environment.

 

[jim mcnamara]

Felidae (cats) have highly reflective layer beneath their retina, the tapetum, which intensifies vision in very low light. They also have ~6 times more rod cells in the retina than humans do. They do not really see very far into IR.

Dogs. Similar rod density, plus a tapetum is also found underneath canid (dog, wolf, etc) retinas. This reflective layer is what makes their cat and dog eyes reflect light in an eerie way under dim conditions.

https://www.livescience.com/40459-what-do-cats-see.html

Dog and cats (dichromats -blue and green) have crummy color vision compared to humans (trichromats). Mantis shrimp are dodecachromats (12 color vision), which is incredible. Just to give perspective.

https://www.livescience.com/42797-mantis-shrimp-sees-color.html

Mammals are limited in the color vision department because their primary lineages arose from small nocturnal animals that lived in burrows, hollow logs, etc., during the 140 million years of dinosaur times.

Mammals arose from Therapsids (Permian)) lived from 290 mya -- 200mya. So. Early mammals were primarily dino chow during the Mesozoic. After they made it through the end of the Cretaceous they became dominant with no competition. Because nearly all of the dinosaur clades died off at that point. Birds arose from theropod dinosaurs and so in some sense as dinosaurs they are still with us.

 

[DaveC426913]

Humans too.

My son can see farther toward IR than I can.
I tested him with the TV remote LED, and he passed with flying colours. To me, it was pitch black.

[ EDIT ] Wow! I had no idea how far into IR they are! 940nm is the standard wavelength. 740 is considered the edge of visible light. (Granted, I assume there's some bleed in cheap LEDs, but still. my son has a superpower!)

 

[Klystron]

Relevant to @BillTre 's excellent post, certain species of mouth-breeding cichlids communicate with a wide spectrum of photophore patterns, particularly for mating purposes to signal desire (male) and receptivity (female) and to 'discuss' nest designs and to maintain social hierarchies. These shallow water cichlids reflect UV, visible and near-IR depending on age and water conditions.

In an unintended experiment a young male yellow African cichlid damaged its photophores while trapped in an aquarium water filter but survived. When mature, the poor fellow engaged in the frequent mouth wrestling common between males but was unable to transmit and answer sexual signals from receptive yellow females. It eventually mated and nested with a green female related species producing interesting hybrid fry.

 

[Rive]

Well, as far as I know actual IR vision is rare.

It happens, that the 'visible' range of the eye of some species is a bit different than ours, but this kind of IR does not really works in dark environment - the source of this IR range is still the Sun, usually (too high temperature needed to emit this range).

There are three types of 'night vision'.
- thermal imaging: this is what some snakes do - pit viper was mentioned before. A real IR vision, works both day and night.
- near IR sensitivity: it requires some IR light source, otherwise it does not work at night. This is what mostly used for security cameras - and animal movies/https://www.amazon.com/dp/B074FVPTRQ/?tag=pfamazon01-20.
- light amplification: the real 'night vision' what most nocturnal animals use. Still not works in absolute dark, by the way.

 

[jim mcnamara]

@Rive
Pit vipers "see" heat, literally IR, 750nm to 1mm - see this nice nature article:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855400/

Those nostril looking holes are where IR detection occurs up to distances of about 1 meter from warm blooded prey.

Lots of images here - my favorite is the eyelash viper
https://www.google.com/search?sxsrf...nAhWSop4KHd7KB18QsAR6BAgKEAE&biw=1536&bih=728

 

[Rive]

Pit vipers "see" heat, literally IR, 750nm to 1mm - see this nice nature article:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855400/

Erm... You wrote that as if I had denied it. Yes, they do see heat: exactly that and not just a tiny range of near-IR. That's why I mentioned them in the first category.

The range of 750nm to 1mm is exactly the common thermal range, while near IR is just ... well, that's more just the neighborhood of the visible range...

Ps.: maybe the source of the confusion is that I referred the visible range variations of the eye separately, as not real IR/night vision? Those snakes are doing their magic trick with a dedicated organ, not with their eyes... Those organic lenses and stuff are just no good for making image out of thermal radiation. They work somewhat with near IR, but not with wide range thermal..

 

[jim mcnamara]

@Rive No, I just cannot write clearly sometimes. Simply wanted to point out specifics and a really good paper in Nature.

 

[BillTre]

Those organic lenses and stuff are just no good for making image out of thermal radiation. They work somewhat with near IR, but not with wide range thermal.

There is a similar issue with microscope optics. I used to work in a lab where they used IR frequencies in confocal microscopes to image more deeply in some tissues.
The lenses and prisms had to be made of special materials for the IR to got through them.

 

[mfb]

Pit vipers "see" heat, literally IR, 750nm to 1mm

That should probably be 1 μm. 1 mm would be terahertz radiation. Yes, the publication writes 1 mm but that is so far away from infrared and so difficult to detect that this must be an error.

 

[jim mcnamara]

I wondered about that.
https://www.sciencedirect.com/science/article/abs/pii/S0968432801000105
seems to be the source...
@mfb
Can you get through the paywall?

 

[Rive]

That should probably be 1 μm. 1 mm would be terahertz radiation. Yes, the publication writes 1 mm but that is so far away from infrared and so difficult to detect that this must be an error.

Good catch. Wiki says 5 to 30μm, but I could not find their references. I've found texts with other old or unaccessible references about 3-10 um:

...The pits are located bilaterally on the upper jaw between the eyes and the nostrils and allow the detection of electromagnetic waves from 3 to 10 µm (Bullock and Diecke, 1956;Goris and Nomoto, 1967;Moiseenkova et al., 2003)...

An article about the transparency of the 'pit' seems to support this range.

 

[mfb]

Can you get through the paywall?

Pit organs absorb IR radiation in two major atmospheric windows: the 3–5 μm range and the 8–12 μm range which matches the IR emission of targeted prey (Grace et al., 1999).
[...]
Imaging IR pit organs in Crotaline and Boid snakes enable them to apprehend prey by detecting the IR radiation they emit in the 8–10 μm range
[...]
Forest fire-seeking beetles (Melanophila acuminata) detect forest fires from 60–100 miles away using pit organs, which detect IR wavelengths in the 2–4 μm range.

I don't find 750 nm mentioned anywhere. Maybe the 1 mm should be 10 μm then.

 

[BillTre]

Apparently, dogs can also sense heat.

Their noses, highly innervated and being evaporatively cooled (by being wet) make OK detectors for greater than ambient temperatures.
Science mag news article here.
Nature research article here (article includes a dog thermograph! So you maybe you can see if it has coronavirus).