June 21, 2016 at 16:20The Perfect Quiet Killer - Chameleon
Scientists could explain the method of capturing prey to these animals only now.
Do you see a talented hunter in this photo? Not? But he is.
Chameleons are amazing creatures. Their vision, skin structure, hunting principle - all this is unique. The chameleon looks a little strange, even funny. But this is for man. And in nature, a chameleon is a dangerous killer, quiet and accurate. True, the chameleon hunts only for relatively small insects, which he is able to swallow. As soon as the chameleon sees the prey, it throws out a long and very sticky tongue at the end (we will talk about the reason for this stickiness below). The language of the chameleon is one of the most developed organs of the body. We can say that this is his sixth limb (if you count his tenacious tail fifth). Using the tongue, a chameleon is able to capture and swallow prey in a third of the weight of the animal. And all this - without the slightest movement of the body, only language works.
How exactly a chameleon captures a victim has remained a mystery for many years. It was difficult to understand even how the animal throws out its tongue at such speed over such distances (two body lengths in fractions of a second). And how the capture of the victim takes place and the chameleon returns to his mouth is an even more complicated question. As it turned out, the reason for the success of the silent hunt is in the stickiness of the chameleon's tongue. It is not just sticky, but extremely sticky.
This property of the tongue is due to the viscosity of the chameleon's saliva . It is 400 times more viscous than human saliva. Under certain conditions, this substance behaves as an elastic solid, and not as a liquid. This is the key to understanding the “language capture” mechanism.
Saliva is produced in very small quantities by the special glands of the tongue. Scientists were able to measure the viscosity of this fluid, despite all the difficulties. Using the bait of the chameleon, it was possible to force the tongue to be thrown out, hitting the microscope slide. Saliva was imprinted on the glass. After that, the second phase of the experiment immediately began - the measurement of viscosity. Scientists used a second glass coated with a control fluid whose viscosity is known. After that, tiny metal balls began to roll down the first and second fluids. The glass was tilted at a certain angle. The maximum angle of inclination at which the ball did not roll, but remained in the test fluid, made it possible to measure the viscosity of this fluid.
“An unexpectedly high saliva viscosity suggests that victims stick to the chameleon’s tongue due to viscous adhesion,” said Pascal Damman, research leader. “But even knowing this value is not enough to determine the strength of viscous adhesion. To measure the adhesion force, we used a dynamic model of the retraction phase. "
Scientists were able to find out that when a tongue hits an insect, the tongue expands, and the area of contact with the victim increases. This means that the adhesion of the insect to the surface of the tongue increases significantly. Despite the fact that the tongue quickly comes back, the cohesion is enough so that the victim does not "break". “Viscous adhesion is an effective way to retain even a very large victim,” says the scientist. Viscous fluid is produced only during the release of the tongue.
Measurement of the viscosity of the chameleon's saliva made it possible to confirm one of the assumptions about how the chameleon keeps prey on the tip of the tongue. Back in the 50s of the last century, the “sticking theory” was created, according to which the victim simply sticks to some sticky substance at the tip of the chameleon’s tongue. After that, the assumption was discarded as untenable, believing that since a chameleon can throw an inedible object out of its mouth, it means that saliva has nothing to do with it. Confirmation was also received from scientists who conducted an experiment with blocking the nerves of the animal responsible for the operation of the tongue. After blocking the nerve channels that control the tip of the tongue, the chameleons were unable to capture the victims. Yes, the tongue was thrown out, but the prey did not stick to it.
Now it turned out that the scientists who wrote about the chameleon in the 50s are still right. Another point is interesting. Chameleons can easily let go of large victims (if the prey is already very strong) due to the fact that the tongue takes a certain shape when thrown out, similar to a bowl. It was called the "suction cup." Small insects immediately appear in the "bowl" when captured. But large prey is only partially covered by the language.
The tongue is thrown out during the work of two muscles on both sides of the chameleon's hyoid bone. He returns in the form of a spiral scroll.
This year, biologists at American Brown University decided to determine how fast chameleons are as hunters. They selected 20 species of chameleons and began to capture the capture of prey by a representative of each species with a speed camera (up to 3000 frames per second). As it turned out, on average, the process of throwing out the tongue takes only 1/20 of a second. Returning the tongue to its original position with the victim takes about half a second. In three seconds, a chameleon can identify and catch up to 4 insects. If the chameleon does not hunt, the tongue is held by a special bone of the lower jaw.
As for the effectiveness of hunting of various species, the most deadly hunters were chameleons of the species Rhampholeon spinosus. Their body size is only 4 centimeters, but the tongue is thrown out to a length 2.5 times the length of the animal’s body. At the same time, the language picks up speed of 100 km / h in just a hundredth of a second.
Slightly less effective hunters are Brookesia superciliaris, Rieppeleon brevicaudatus, and Trioceros hoehnelii. Their tongue is twice as long as their body. And the least deadly for the victim is the giant chameleon Furcifer oustaleti, growing to a size of 60 centimeters or more.
According to experts, the accuracy of the language cast of small species of chameleons is explained by high energy consumption. If the little chameleon misses, he will have to gain strength for the next attack. But the big chameleon has enough energy for a second throw.
Of course, change the color and pattern of the body. This makes the animal even more deadly to its victims. The ability to change color is associated with the structure of the skin of the chameleon. A large number of chromatophore cells are located in the outer layer of the skin. These cells contain pigment grains of various colors, including black, dark brown, reddish and yellow. The combination of these colors allows the chameleon to color its skin in many different shades.
In addition to the chromatophore, chameleons also have special cells with crystals inside , which can reflect and refract light. And in the deepest subcutaneous layer of the chameleon, scientists have discovered crystals that help the animal reflect infrared radiation. Thanks to these cells, the chameleon can reflect infrared radiation, while maintaining body temperature in the heat.
An animal can quickly change body color from black to whitish. In this case, the color of not all skin, but some part of it may change.
Color changes under the influence of various factors, including the external environment and the state of the animal. Some types of chameleons change their skin color not to hide, but to communicate with representatives of their species.
Do you see a talented hunter in this photo? Not? But he is.
Chameleons are amazing creatures. Their vision, skin structure, hunting principle - all this is unique. The chameleon looks a little strange, even funny. But this is for man. And in nature, a chameleon is a dangerous killer, quiet and accurate. True, the chameleon hunts only for relatively small insects, which he is able to swallow. As soon as the chameleon sees the prey, it throws out a long and very sticky tongue at the end (we will talk about the reason for this stickiness below). The language of the chameleon is one of the most developed organs of the body. We can say that this is his sixth limb (if you count his tenacious tail fifth). Using the tongue, a chameleon is able to capture and swallow prey in a third of the weight of the animal. And all this - without the slightest movement of the body, only language works.
How exactly a chameleon captures a victim has remained a mystery for many years. It was difficult to understand even how the animal throws out its tongue at such speed over such distances (two body lengths in fractions of a second). And how the capture of the victim takes place and the chameleon returns to his mouth is an even more complicated question. As it turned out, the reason for the success of the silent hunt is in the stickiness of the chameleon's tongue. It is not just sticky, but extremely sticky.
This property of the tongue is due to the viscosity of the chameleon's saliva . It is 400 times more viscous than human saliva. Under certain conditions, this substance behaves as an elastic solid, and not as a liquid. This is the key to understanding the “language capture” mechanism.
Saliva is produced in very small quantities by the special glands of the tongue. Scientists were able to measure the viscosity of this fluid, despite all the difficulties. Using the bait of the chameleon, it was possible to force the tongue to be thrown out, hitting the microscope slide. Saliva was imprinted on the glass. After that, the second phase of the experiment immediately began - the measurement of viscosity. Scientists used a second glass coated with a control fluid whose viscosity is known. After that, tiny metal balls began to roll down the first and second fluids. The glass was tilted at a certain angle. The maximum angle of inclination at which the ball did not roll, but remained in the test fluid, made it possible to measure the viscosity of this fluid.
“An unexpectedly high saliva viscosity suggests that victims stick to the chameleon’s tongue due to viscous adhesion,” said Pascal Damman, research leader. “But even knowing this value is not enough to determine the strength of viscous adhesion. To measure the adhesion force, we used a dynamic model of the retraction phase. "
Scientists were able to find out that when a tongue hits an insect, the tongue expands, and the area of contact with the victim increases. This means that the adhesion of the insect to the surface of the tongue increases significantly. Despite the fact that the tongue quickly comes back, the cohesion is enough so that the victim does not "break". “Viscous adhesion is an effective way to retain even a very large victim,” says the scientist. Viscous fluid is produced only during the release of the tongue.
Measurement of the viscosity of the chameleon's saliva made it possible to confirm one of the assumptions about how the chameleon keeps prey on the tip of the tongue. Back in the 50s of the last century, the “sticking theory” was created, according to which the victim simply sticks to some sticky substance at the tip of the chameleon’s tongue. After that, the assumption was discarded as untenable, believing that since a chameleon can throw an inedible object out of its mouth, it means that saliva has nothing to do with it. Confirmation was also received from scientists who conducted an experiment with blocking the nerves of the animal responsible for the operation of the tongue. After blocking the nerve channels that control the tip of the tongue, the chameleons were unable to capture the victims. Yes, the tongue was thrown out, but the prey did not stick to it.
Now it turned out that the scientists who wrote about the chameleon in the 50s are still right. Another point is interesting. Chameleons can easily let go of large victims (if the prey is already very strong) due to the fact that the tongue takes a certain shape when thrown out, similar to a bowl. It was called the "suction cup." Small insects immediately appear in the "bowl" when captured. But large prey is only partially covered by the language.
The tongue is thrown out during the work of two muscles on both sides of the chameleon's hyoid bone. He returns in the form of a spiral scroll.
How fast is a chameleon?
This year, biologists at American Brown University decided to determine how fast chameleons are as hunters. They selected 20 species of chameleons and began to capture the capture of prey by a representative of each species with a speed camera (up to 3000 frames per second). As it turned out, on average, the process of throwing out the tongue takes only 1/20 of a second. Returning the tongue to its original position with the victim takes about half a second. In three seconds, a chameleon can identify and catch up to 4 insects. If the chameleon does not hunt, the tongue is held by a special bone of the lower jaw.
As for the effectiveness of hunting of various species, the most deadly hunters were chameleons of the species Rhampholeon spinosus. Their body size is only 4 centimeters, but the tongue is thrown out to a length 2.5 times the length of the animal’s body. At the same time, the language picks up speed of 100 km / h in just a hundredth of a second.
Slightly less effective hunters are Brookesia superciliaris, Rieppeleon brevicaudatus, and Trioceros hoehnelii. Their tongue is twice as long as their body. And the least deadly for the victim is the giant chameleon Furcifer oustaleti, growing to a size of 60 centimeters or more.
According to experts, the accuracy of the language cast of small species of chameleons is explained by high energy consumption. If the little chameleon misses, he will have to gain strength for the next attack. But the big chameleon has enough energy for a second throw.
What else can a chameleon do?
Of course, change the color and pattern of the body. This makes the animal even more deadly to its victims. The ability to change color is associated with the structure of the skin of the chameleon. A large number of chromatophore cells are located in the outer layer of the skin. These cells contain pigment grains of various colors, including black, dark brown, reddish and yellow. The combination of these colors allows the chameleon to color its skin in many different shades.
In addition to the chromatophore, chameleons also have special cells with crystals inside , which can reflect and refract light. And in the deepest subcutaneous layer of the chameleon, scientists have discovered crystals that help the animal reflect infrared radiation. Thanks to these cells, the chameleon can reflect infrared radiation, while maintaining body temperature in the heat.
An animal can quickly change body color from black to whitish. In this case, the color of not all skin, but some part of it may change.
Color changes under the influence of various factors, including the external environment and the state of the animal. Some types of chameleons change their skin color not to hide, but to communicate with representatives of their species.