Glowing amphibians such as frogs are more common than previously thought

Glowing amphibians such as frogs may be more common than previously thought, according to a new study.

US biologists found more than 30 species of amphibians, including toads, frogs, newts and salamanders, all showed a natural phenomenon called ‘biofluorescence’. 

Biofluorescence, where organisms emit a fluorescent glow after absorbing light energy, may be widespread in amphibians, the team conclude.   

The researchers say it may help amphibians find each other in dim light, attract mates or help camouflage themselves in the face of predators. 

The colourful effect had previously only been observed in one salamander and three frog species. 

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The marbled salamander (left) and the eastern tiger salamander (right) both showed biofluorescence – they emitted a fluorescent glow after absorbing light energy

Other species used in the study, top left from clockwise: Northern dwarf siren, Alpine newt, three-lined salamander and spotted dusky salamander

Other species used in the study, top left from clockwise: Northern dwarf siren, Alpine newt, three-lined salamander and spotted dusky salamander

The team, from St. Cloud State University in Minnesota, exposed somewhere between one to five creatures from 32 amphibian species to blue or ultra-violet light. 

This included common North American species such as the American toad, the wood frog, the California giant salamander and the green pacman frog, which is kept in the US as a pet. 

While most of the 32 species are from North America, others observed are native to South America (such as the Amazon milk frog) Europe (Alpine newt) and China (Fire belly newt). 

Close-up of the Alpine newt (Ichthyosaura alpestris). The study suggests the ability to emit the fluorescent glow after absorbing light energy may be widespread in amphibians, including those that weren't used in the study

Close-up of the Alpine newt (Ichthyosaura alpestris). The study suggests the ability to emit the fluorescent glow after absorbing light energy may be widespread in amphibians, including those that weren’t used in the study

Bioflourescence in a dwarf siren salamander, which ranges in length from about 4 to 10 inches

Bioflourescence in a dwarf siren salamander, which ranges in length from about 4 to 10 inches

Close-up of the Alpine newt (Ichthyosaura alpestris). The biggest of the males can reach up to 3.5 inches and the females 4.7 inches

Close-up of the Alpine newt (Ichthyosaura alpestris). The biggest of the males can reach up to 3.5 inches and the females 4.7 inches

The team measured the wavelengths of light emitted by the animals using a spectrometer, an instrument used to measure properties of light over a portion of the electromagnetic spectrum.

All the creatures that were exposed to light – 50 in total – showed varying degrees of biofluorescence in different body parts. 

Fluorescent patterns differed between species, from blotches and stripes to fluorescent bones and all-over fluorescence.

A Rio Cauca caecelian. Caecilians are a group of serpentine amphibians that completely lack limbs

A Rio Cauca caecelian. Caecilians are a group of serpentine amphibians that completely lack limbs

Closeup of a fringed leaf frog in defensive pose - one of the many amphibian species that displays biofluorescence. This could be as a means of camouflage or attracting a mate

Closeup of a fringed leaf frog in defensive pose – one of the many amphibian species that displays biofluorescence. This could be as a means of camouflage or attracting a mate 

The green pac man frog. Scientists found patterns of fluorescence differ substantially between species ranging from illuminated blotches and stripes, to bones or all-over fluorescence

The green pac man frog. Scientists found patterns of fluorescence differ substantially between species ranging from illuminated blotches and stripes, to bones or all-over fluorescence

WHAT IS BIOFLUORESCENCE? 

Biofluorescence is the absorption and emission of light from living organisms.

These organisms have proteins in their skin or other tissues that absorb light.

This causes the light that is emitted to be a different colour than the light that is absorbed.

Fluorescence is the temporary absorption of electromagnetic wavelengths from the visible light spectrum by fluorescent molecules, and the subsequent emission of light at a lower energy level.

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