General, Research, Technology

Why are frogs colored differently?

Almost in all corners of our planet livefrogs are amphibians with bulging eyes and no tail. To date, scientists are aware of the existence of about 2,500 species of frogs, which differ from each other in size, lifestyle and skin color. In nature, there are quite a few frogs of yellow, red and even blue, but most of them are colored green. But what exactly determines the color of these creatures? Scientists have been looking for an answer to this question for many years and, in general, it has already been found. However, in the course of each scientific work they become aware of even more interesting facts. So, these croaking creatures only seem unremarkable - in fact, many complex processes take place inside their organisms.

A transparent frog of the species Hyalinobatrachium yaku was discovered relatively recently, in 2017

Animal colors

As a rule, the outer cover of amphibians,insects and many other creatures play an important role in their lives. Some animals, with the help of their coloring, skillfully disguise themselves in nature and hide from predators. There are also brightly colored creatures that, with all their appearance, warn attackers about their danger - most often, they are poisonous. Frogs are not on the exemption list and also use their skin for two purposes:

  • to scare away predators (warning color);
  • and for camouflage from predators (protective color).

Special cells are responsible for coloring the skin of frogs, referred to as chromatophores... They are also found in many fish, crustaceans andcephalopods. I talked in more detail about the work of these cells in the material on how chameleons change the color of their skin - these cells play a key role in this process. In short, chromatophores contain coloring substances. The activity of these cells depends on many factors, such as environmental conditions and the emotional state of cold-blooded animals. But, for the purposes of this article, we only need to know what exactly they are responsible for the skin color of frogs.

Red tomato frog (Dyscophus antongilii)

The most poisonous frog

The most poisonous frog in the world is considered a terribleleaf climber (Phyllobates terribilis). Above I have already mentioned that many poisonous creatures warn of their danger with their bright appearance. The terrible leaf climber also takes care of its enemies and communicates its toxicity with the help of its yellow skin. The outer cover of this frog is covered with a poisonous substance known as batrachotoxin. One frog contains enough venom to kill 10 adult and perfectly healthy males. So, at least, it says in various scientific sources.

Terrible leaf climber frog (Phyllobates terribilis)

Batrachotoxin acts on the human body as follows:

  • disrupts the work of the heart;
  • interferes with lung function;
  • paralyzes the muscles of the body;
  • prevents cells from transmitting nerve impulses.

The danger of terrible leaf climbers increases bythe fact that scientists still do not know how to stop the destructive effect of batrachotoxin on the human body. But they already know that when mixed with scorpion venom, batrachotoxin becomes 12 times more dangerous. Yes, it would be better if they could find a method to weaken the poison.

See also: Why do frogs have such a strange skull shape?

Transparent frogs

With colorful frogs and their greenrelatives who live in huge numbers on the territory of Russia, everything is clear. The former use bright body coloration to warn enemies, and the latter for protection. The skin quite copes with the tasks imposed on it. Poisonous frogs are clearly visible from afar, and green ones are almost invisible. At least, on the surface of dirty land near various bodies of water.

Another dangerous frog - Zimmerman's Dart frog (Ranitomeya variabilis)

But did you know that there are frogs in the world withtransparent skin? The so-called glass frogs (Centrolenidae) get their name because the internal organs can be seen through their skin. But how do they warn of their toxicity and disguise themselves against the background of nature? After all, the brain and digestive system that are visible through and through do not do anything useful - they do not scare away animals and do not really allow them to disguise themselves.

Glass frogs show all the insides. At least from below

Fortunately, evolution has taken excellent care of eventiny frogs. The fact is, the backs of transparent frogs can turn green. Scientists could not understand how this happens for a long time, but recently the answer was finally found and published in the scientific journal PNAS. As it turned out, some frogs, although they have transparent skin, can be colored inside. And in this they are helped by a substance called biliverdin.

Frogs turn green due to the interaction of two chemicals

This poisonous substance is destructive practically forall living organisms and, if you think logically, should kill frogs. But no - their organisms also contain a chemical compound with the complex name biliverdin-binding serpin. It neutralizes the toxic effect of the coloring matter and at the same time makes the light green shade of biliverdin darker. As a result, transparent frogs can disguise themselves without any problems, just like their closest relatives.

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About the "green spots" on the backs of transparentI already wrote about frogs in the article about animals with colorless skin. I recommend reading, because it touches on the topic of transparency not only of amphibious creatures, but also of fish. Enjoy reading!