1. How Fast Does a Chameleon's Tongue Shoot Out When the Body Is Cooled to 15°C?
Chameleons are animals that catch insects by extending a long tongue in an instant. Researchers studied the speed of this tongue by changing the animal's body temperature. The maximum speed averaged 4.4 m/s at 35°C, but remained at an average of 3.4 m/s even at 15°C [4]. This means that even though the temperature dropped by 20°C, the tongue’s maximum firing speed stayed at about 77% of its speed at 35°C (3.4 ÷ 4.4 ≈ 0.77). These numbers refer only to the "firing" of the tongue; the movement to pull it back slows down differently [4].
It is a general trend for cold-blooded animals to slow down when their body temperature drops. Yet, this tongue resists slowing. To understand why, we first look at the "normal" way animals slow down.
2. How Much Do Running, Swimming, and Jumping Slow Down When Animals Are 10°C Cooler?
Animals whose body temperature changes with the outside air are called cold-blooded animals. Animals other than mammals and birds are considered to be in this group [1].
One study summarizes movement when cold. It reports that when body temperature drops by 10°C, the running speed of lizards, swimming speed of fish, and jumping distance of frogs drop by at least 33% [4]. Since 33% is a lower estimate, the drop can be even larger.
There is another guideline for biological reactions. The Q10 value shows how many times faster a reaction becomes when the temperature rises by 10°C. Values vary by reaction, but 2 to 3 are common [3]. If Q10 is 2 to 3, speed drops to half or one-third when the temperature falls by 10°C. The earlier "at least 33%" is a reported lower limit, while Q10 is a separate general guideline.
Now that the numbers are clear, what is slowing down inside the body?
3. Why Cold Slows Movement: Chemical Reactions in the Body Slow Down
Inside the body, many chemical reactions, such as extracting energy from food, proceed without rest. Enzymes help these reactions.
Chemical reactions generally become faster as temperature rises and slower as it falls. This is because the energy needed to drive reactions is easier to obtain at higher temperatures [2]. Enzymes work the same way. However, above a certain temperature an enzyme changes shape and loses its function, so each enzyme has an optimal temperature. Conversely, enzymes do not break down at low temperatures; they just slow down [2].
Muscles follow the same pattern, and the speed of contraction is affected by temperature. The study mentioned earlier states that environmental temperature affects activity through the physiology of muscle contraction [4].
If the outside temperature becomes extremely low, body temperature also drops, metabolism slows severely, and normal activity becomes impossible, leading to a dormant state [1]. The temperature at which animals become immobile differs by species. However, animals are not just waiting to get cold.
4. How Lizards and Turtles Seek Warm Places Before Becoming Immobile in the Cold
There is a report on the running speed of a lizard species (Sceloporus occidentalis) at different temperatures. Speed is highest at their preferred body temperature of about 35°C. In the range of 25–35°C, the difference due to temperature is small (Q10 is 1.23), but the effect becomes sudden and large when temperatures drop below 25°C [5]. This means the effect is small if they are only slightly cold, but the impact on running speed increases sharply once a certain temperature is crossed.
Animals also change their behavior to regulate body temperature. In general, they prefer warmer temperatures when active, which raises metabolism, and cooler temperatures when resting, which lowers it. Freshwater turtles, for example, bask in the sun at noon to adjust their body temperature [6].
Avoiding cold and warming up. So, how do they spend the winter, the coldest season?
5. How Land Animals Spend Winter: Moving to Milder Places and Stopping Movement
Many cold-blooded animals living on land spend winter in an inactive state (hibernation or dormancy). They lower their metabolism in autumn and become inactive. Cold-blooded animals living in water are said to spend winter relatively actively [7].
There are characteristics to the places where hibernation begins. For cold-blooded animals, body temperature drops in parallel with outside air temperature. If it falls below a certain limit, they cannot move their bodies or grow. Therefore, they move to places where the temperature does not drop much, such as underground, under stones or fallen logs, or in the mud at the bottom of water, before entering hibernation [8].
By doing two things—not moving and hiding in places that stay warm—they survive the winter cold. Some animals move parts of their bodies in ways less affected by cold.
6. Why Chameleon Tongues Resist Cold: They Use Elastic Force Like a Spring
The force that shoots the chameleon’s tongue is elasticity, like a spring. The Q10 value, which shows the effect of temperature on speed, is small at 1.1–1.3. This is much lower than the Q10 for muscle contraction speed taken from the body, which generally exceeds 1.5 [4].
In contrast, the movement of pulling the tongue back using muscle force drops by about 42–63% for every 10°C drop, according to a summary [4]. In the same body, movements using elastic force are less affected by temperature, while movements using muscle force are greatly affected.
This is an example of how cold-resistance strategies exist not just in behavior, but in the way the body moves itself. Besides this, there are fish that avoid cold by changing the shape of their enzymes.
7. How Antarctic Fish Swim in Seas Below 0°C by Changing the Shape of Their Enzymes
The seas around Antarctica can drop below 0°C, but many fish are active there [7]. Enzymes have pocket-like parts that take in substances. If the opening and closing of these pockets slows down due to lower temperatures, production efficiency drops. Antarctic fish are explained to use smaller amino acids in the hinge-like parts of these pockets, making them easier to open and close (an example using lactate dehydrogenase) [7].
In a detailed study of this enzyme, lactate dehydrogenase A4 in fish around Antarctica (Notothenioids) adapted to low temperatures by increasing the flexibility of small molecular regions. The average number of reactions per second was reported as 240, which was more than four times that of the species adapted to the warmest places [9]. The comparison was not with all fish species, but with species from the warmest places.
It is not yet known if this mechanism applies to other enzymes [7].
8. Try It Yourself: Compare the Temperature of Sunny and Shaded Ground
On a sunny day, try touching the ground in the sunlight and the ground in the shade to compare them. Do this with an adult in a safe place. Do not touch hot ground like asphalt. If you see a lizard or a turtle, do not chase it. Instead, record once whether the place you found it was in the sun or shade. It might be there to warm its body.
If you want to learn more, look up "cold-blooded animals," "hibernation," and "chameleon" in libraries or encyclopedias. Public materials from universities and research institutions also summarize the relationship between temperature and living things.