Humans did not discover infrared light until the 1800s, and it took us significantly longer to begin figuring out what this part of the visible light spectrum means. But there are many species that have an advantage of hundreds of thousands of years before us. The creatures around us have used their ability to see infrared light as a way to hunt, defend and navigate the world in ways that we humans could never have foreseen before the discovery of infrared radiation.
All cases of infrared vision that researchers have finally discovered appear in cold-blooded species such as snakes, amphibians and insects. In other words, the most alien of our natural predators tend to have infrared vision. But there are some indications that more common mammals can detect the infrared spectrum. Our list will include creatures that definitely use the infrared spectrum to see, as well as those that supposedly only use the infrared spectrum. You can even peer into both the infrared and ultraviolet spectrum. Either way, this unique vision plays a critical role in the survival of these species.
No. 8. Bull frog – eyes for any situation
The eyes of frogs adapt to the analysis of visible or infrared light in the same way as salmon, with the help of an enzyme that converts vitamin A1 to A2. Although the bullfrog converts mainly into A1 pigments as it grows from a tadpole shape into an adult, it retains the ability to see infrared radiation from the bottom of the eye, seeing visible light from above. To maximize their prey potential, bullfrogs often sit half-surfaced, patiently looking for flies above the water, using their infrared vision below the surface to look for potential predators.
If all you know about the bullfrog is its signature croak, you can catch up on this adorable amphibian here.
No. 7. Wolf – the smell of warmth
While the verdict on whether foxes can see infrared light may be open, there is strong evidence that wolves and other related dogs are able to perceive this spectrum in their own way. In fact, the recent discovery that wolves and dogs can actually smell heat through their noses is forcing us to rethink our understanding of the infrared spectrum and its relationship to mammals. Although dogs have been trained to rely primarily on other senses, it is believed that they can be trained to feel better, and that wolves still use this sensory trick in the wild. If true, coyotes may have the same abilities.
Wolves are apex predators that can’t even smell warmth, and here’s more information on their complex social habits.
No. 6. Vampire bat – warm-blooded hunter
Speaking of bloodsuckers, the vampire bat is another warm-blooded prey hunter that benefits from its intimate connection with the infrared spectrum. The senses used by vampire bats are similar to the pit sensors used by vipers. But the shape used by the vampire bat is actually more complex, as it can determine the threshold for dangerous heat when temperatures reach 109 degrees Fahrenheit, as well as determine the threshold for warm-blooded prey that occurs at 86 degrees.
The name “vampire bat” may evoke thoughts of gothic monsters, but the real truth about these nocturnal predators can be found here.
No. 5. Mosquito – bloodsuckers seeking warmth
Drinking blood is a fairly common form of support in the animal kingdom, but most animals that ingest plasma track their game by smelling the carbon dioxide emitted by our bodies. And while mosquitoes do use the smell of this chemical to identify prey from a distance, their infrared vision allows them to get close enough to visually identify a target. This gives mosquitoes three different senses that they can use to hunt, although they can only rely on one or any combination of the three depending on the circumstances.
No. 4. Fox – Potentially Deceiving Technology
While it has been proven that the only creatures that see infrared light are cold-blooded, there are some exciting signs that foxes – and possibly other nocturnal mammals such as coyotes – can read light that appears in the infrared spectrum. … But anecdotal evidence suggests that foxes and other animals are capable of detecting and actively avoiding hunting cameras that use infrared technology to detect animals at night. Unfortunately, the task of isolating infrared radiation as a variable in research is difficult, and therefore the question of whether foxes, coyotes and other mammals can actually sense infrared radiation is still open.
Even if they can’t see infrared light, foxes have a variety of tricks you can learn about here.
No. 3. Goldfish – a truly unique outlook on life
Fish can usually see deeper in the red spectrum than humans, simply because it is such an important attribute for survival underwater – but no fish that has yet been discovered has the unique sensitivity range of the goldfish. Their field of view ranges from infrared to ultraviolet. Infrared light is measured as a longer wavelength than visible light, and ultraviolet light is measured as shorter than the wavelength of visible light. Through the use of four-color cones in the eye, the goldfish can better see and correctly measure not only food and threats in visible light, but also based on their reflection in the water.
Goldfish are also a popular choice for adoption as a pet, and you can learn about their grooming habits here.
No. 2. Pit Viper – Feeling Without Seeing
Although the viper is capable of sensing light in the infrared spectrum, this is not exactly what we humans call vision in the traditional sense. Instead, they use “pit sensors” that are located along their jaws and can register changes in the thermal spectrum. The nerve cells that make up these organs detect heat at the molecular level and then heat the fossa sensor, triggering an electrical signal that causes the viper’s brain to respond. But instead of using this sense as an alternative to traditional vision, the pit viper is believed to combine normal vision with these pit sensors for a fuller sense of situational awareness.
# 1. Salmon – adaptation of vision to circumstances
Salmon are known for their epic mating migrations, which often carry them from one end of the world to the other, but aside from going through some rather complicated mating rituals, the way their eyes work actually changes over the course of their journey. A biochemical reaction occurs in their eyes as they transition from fresh to salty environments, as the infrared and near-red spectrum makes it easier to navigate the saltier and often darker ocean waters. This is a transition that boils down to a very simple chemical process – the conversion of vitamin A1 into vitamin A2 using an enzyme that is naturally produced by the salmon body.
Salmon is more than just a delicious main course, and here you can get to know more about this common fish.
Next: Playing Possum: 9 Animals Playing Dead to Survive