Tree frogs are quite common in tropical areas. And many people often get pretty surprised to see tree frogs changing color within the blink of an eye. Yes, that’s true. Tree frogs are well known to have an amazing physical trait of changing colors. And researchers throughout the decades have found out some amazing data on why and how they do it.
Tree frogs mainly change color before mating in order to attract the female tree frogs. They can also change color to avoid predators, thermoregulation, intercommunication or a change in the environment.
In this article, I’ll try to highlight some amazing facts on this sudden fluctuation of colors in tree frogs.
What Kind Of Frogs Change Colors?
Frogs can be classified into two classes based on color change. They are:
- Monochromatic frogs.
- Dichromatic frogs.
Monochromatic frogs do not possess the ability to change colors. They cannot change the color of their skin under different situations even if it’s essential.
Dichromatic frogs have the ability to change color at least once in their entire life cycle. This change can be either temporary or permanent. Most of their physiologic and behavioral instincts are firmly associated with color changing.
The red-eyed tree frog mainly belong to the Family Rhacophoridae and Hylidae. The name Hyla is derived from Latin, which means ‘Variable color’. The Rhacoporus is a genus of Rhacophoridae, which comprises two genera Leptomantis and Zhangixalus. There are almost 39 species of Dichromatic Tree frogs.
Pigmented Skin Plays The Main Role
The epidermis of the frog’s skin plays the most vital role here. Their color changing is stimulated by various extrinsic factors, but initiated and controlled by the three layers of pigment present in the frog’s epidermis. These layers allow the transformation of colors in their skin.
The upper shell of their coat has a marked outline that resembles lichen. These outlines may vary from species to species, but features two main patches, green or brown. So the color change mainly ranges from Green to brown.
How Do They Change Color?
Dichromatic frogs show two types of color change, permanent and temporary. Permanent change in coloration takes place after the frog reaches adulthood. The temporary color change can occur anytime depending on extrinsic stimulating factors.
Permanent and temporary color changes happen through two diverse processes.
- Morphological change.
- Physiological change.
Morphological Color Change
The Permanent color change occurs morphologically. During a phase in a tree frog’s life cycle, it changes its color permanently. The process can take several days to several months.
The outer layer of the skin is called Chromatophore. In this outer layer, a notable change takes place in the density of pigment-containing cells. And it results in a changed color.
This morphological change stays for either one mating season or a lifetime. It mainly takes place at the onset of the first mating season.
Physiological Process Of Changing Color
The second one is Physiological change. It is initiated by the stimulation of several intrinsic body factors or extrinsic environmental factors. This process accounts for only a few seconds to hours.
A sudden fluctuation in the density of pigment-containing granules causes this rapid change. It is done by the dispersion and aggregation of the former and new color pigments, respectively. The whole process is controlled by hormones through the neuroendocrine system and messenger chemicals through the neuromuscular system.
The physiological changes are seen for a short period. It occurs because of a lot of reasons, which we will discuss in the latter portion of this article.
Why Do They Change Color?
As I’ve discussed earlier, change in coloration occurs due to several reasons. Several factors facilitate color change. It mainly works as a compensatory method in some instances. The main reasons are mentioned below:
- Male frogs change color before mating.
- To avoid predators.
- Change in environment.
Color Change Before Mating
That’s the most and neutral color change found in tree frogs. Male Tree frogs tend to change their colors to attract female partners. Sometimes the changes are temporary and sometimes they are irreversible. In many species, the change becomes permanent as soon as they hit sexual maturity.
The bright colors attract the female partners the most. And there’s a competition noticed among male frogs to appeal to female frogs for mating. So this change is more Intersexual. These color changes range from green to grey to blue sometimes.
But Intersexual signal is not the only purpose here. Male Tree frogs send Intra-sexual signals to other male frogs to keep them away from mating their selected partners. They even use this change in coloration to establish their dominance in the group.
Research led by Rayna Bell, a research zoologist at Smithsonian’s National Museum of Natural History proved some amazing facts about this change. She believes it requires more research to find out the signaling method using change of coloration.
Unfortunately, the vibrant colors attract not only female frogs but also invite predators. So tree frogs use their ability of color changing to hide from potential threats.
Whenever a tree frog expects a potential threat, it quickly transforms its color. The color depends solely on the background. There is a link between physiological disturbance and stress with this fluctuation.
The Foundation for Biodiversity Conservation in Pune, India, has conducted research on it. The director, Varad Giri has said:
Tree frogs change colors under stress. When they hid under rocks, they adapted to the color of it.
He also added that the reason for this color change is Camouflage. By combining in with the backdrop, frogs can get away from predation.
Color change has a big role to play in thermoregulation. A lot of researchers deny this point. There are innumerous numbers of pores in a frog’s skin. Whenever the temperature increases, the frog’s skin becomes less permeable to waters. Thus, regulate thermoregulation.
But there’s a link between solar absorbance of heat and color change. When the body loses too much water, it secretes some kind of chemical substances that make its body waterproof. This is when color change regulates thermoregulation.
Tree Frogs use color change to maintain intercommunications. Whenever one of the members of the group notices any threat, it changes its color to warn the rest. They also do it while searching for food or hunting.
Change In Environment
From an ecological point of view, Tree frogs travel from one place to another in different seasons. So the change in the environment plays a big role in color change. The temperature is another big factor here.
The rate of color change is slower in high light intensity, brown background, and higher in the green background and low light intensity. At 25 degrees Celsius the rate is slower than that of 10 degrees Celsius.
Sometimes color change can be caused by the byproducts of hormone secretion due to stress. It indicates physiological disturbance within the frog’s body. Stress and other diseases can be the root of this problem.
Green Or Brown?
The colors solely depend on the background. Whenever a tree frog is clinging to a green object, it turns green. Similarly, when the frog attaches its body to any brown object, it transforms its color to brown.
It’s really an interesting thing to see your pet frog changing color. It can be really entertaining unless it’s associated with something unwanted. So before enjoying this transformation, make sure all the factors are in its favor.
You definitely wouldn’t like to freak your frog out to enjoy this. Always try to maintain things properly to ensure a safe and friendly environment for your frogs. Any unwanted situation can lead to unwanted consequences. And the change of coloration can be a real good indicator of your frog’s condition.