UV-illuminated creatures: the puzzle of pink squirrels and green sharks explained
Discovering the Glow: The Fascinating World of Photoluminescence in Nature
In backyards across the globe, citizen scientists have been making an intriguing discovery: glowing geckos and millipedes, illuminated under the light of UV flashlights. This is just one facet of a larger phenomenon, the property known as photoluminescence, which is increasingly being found in a diverse array of animals.
According to Linda Reinhold, a zoologist at James Cook University in Australia, most animals exhibit a glow when observed at night. This observation is supported by research, which indicates that 95 species of coral reef fish and 95 percent of 148 mammals, as well as 181 species of bird and 92 percent of 187 frog species, all display photoluminescent properties.
The primary function of photoluminescence (specifically bioluminescence) in animals is to serve as a biological light emission system that aids in various ecological interactions, particularly predator-prey dynamics. Bioluminescence can be used for attracting prey, deterring predators, camouflage, or communication.
In predator-prey interactions, bioluminescence affects behavior in several ways. Some animals, like certain siphonophores, use bioluminescent lures that mimic prey or other attractive objects to draw in prey, thereby aiding their capture. Bioluminescence combined with fluorescence can also mimic other organisms or environmental features to confuse or attract prey, as with species of the genus Erenna and others.
Though less about photoluminescence itself, related biological strategies include ink clouds (in some mollusks) that use chemical and sensory disruptions to confuse predators, facilitating escape.
The biochemical mechanism underlying this bioluminescence involves the enzyme luciferase acting on the substrate luciferin in the presence of oxygen, producing light without significant heat.
Researchers like David Gruber have been uncovering these glowing creatures in the ocean, discovering that various marine creatures, such as sharks and sea turtles, glow under UV light. However, understanding how these colors are perceived by both the creatures displaying them and their predators could help reveal their function.
For instance, birds prefer to eat caterpillars that were not photoluminescent, hinting at the possibility that insects use an ultraviolet glow as a way to warn off predators. In the case of snakes, there appears to be no difference between male or female snakes with regard to UV coloration.
In the terrestrial realm, glowing markings on the wings of tube-nosed fruit bats may help them hide among leaves during the day, while scorpions may be able to use their glowing exoskeletons to sense ultraviolet light and move away from it. Prairie rattlesnakes have almost no UV coloration, while tree vipers found in the tropics from the genus Bothrops display full UV coloration.
The upper parts of the ocean act like a blue light filter, allowing only UV light to permeate farther depths. This could explain why certain deep-sea creatures, like anglerfish and jellyfish, are bioluminescent, as they rely on UV light to navigate and communicate.
As our understanding of photoluminescence continues to grow, so too does the awe and wonder it inspires. This fascinating phenomenon, which enables animals to manipulate visibility in their environment, influencing interactions with both predators and prey by either attracting, deterring, or hiding, provides significant survival advantages in many marine and some terrestrial environments.
- The glowing geckos and millipedes discovered in backyards are part of a larger phenomenon, photoluminescence, found in a diverse array of animals, such as species of coral reef fish, mammals, birds, frogs, and even deep-sea creatures like anglerfish and jellyfish.
- In the ocean, the upper parts act as a blue light filter, allowing UV light to permeate deeper levels, where certain species, like anglerfish, rely on this bioluminescence to navigate and communicate.
- Bioluminescence in animals serves various ecological interactions, particularly predator-prey dynamics, and is used for attracting prey, deterring predators, camouflage, or communication.
- Some marine creatures, such as sharks and sea turtles, are found to glow under UV light, and the understanding of how these colors are perceived by both the creatures and their predators could reveal their function.
- In the terrestrial realm, glowing markings on the wings of tube-nosed fruit bats might help them hide among leaves during the day, while scorpions may use their glowing exoskeletons to sense ultraviolet light and move away from it.
- Scientific research in environmental science, particularly in the field of medical conditions, could potentially benefit from the study of photoluminescence, as the mechanics underlying this bioluminescence may lead to new discoveries and advancements in lifestyle technology.
