Shark Biology: An Interesting Explanation for the White Stomachs of Great Whites
In the world of marine life, the great white shark stands out for its remarkable ability to change its skin color in real time. This dynamic color change, first detailed by artist Abbott Handerson Thayer in 1909, plays a crucial role in the shark's camouflage, enabling it to better blend into its environment and reduce detection by prey or predators.
The color change is primarily controlled through hormonal mechanisms involving adrenaline and melanocyte-stimulating hormone (MSH), which cause the shark's skin to become lighter or darker. This adaptive coloration, often referred to as countershading, creates a darker top and lighter underside that makes it difficult for other animals to discern the shark's outline, especially from above.
Hannah Rowland, a Senior Lecturer in Ecology, Evolution, Ecology and Behavior at the University of Liverpool, explained in 2008 that this countershading works by canceling out the natural light, making it harder for observers to determine an object's location. The darker pigment on great white sharks is not only for UV protection, but it might also be used to enhance their countershading advantage in response to hormones like adrenaline.
Michelle Jewell, who studies great white shark behavior at Michigan State University Museums, stated in 2022 that these color changes can occur in real time. Previously, the leading hypothesis for the color changes was that the sharks were simply getting a tan after spending time in shallow water, but early experimental evidence suggests a faster color change that happens in response to hormones.
Interestingly, this color-changing ability is linked to specialized skin structures called dermal denticles. These structures contain pigments and crystal stacks (likely guanine) that interact to produce different perceived colors. Small changes in the arrangement of these nanoscale structures allow the shark to modulate its coloration subtly but effectively. This mechanism differs from typical pigment-based color change and resembles dynamic structural coloration seen in some other animals, such as chameleons and blue sharks.
The adaptive significance of this color-changing ability lies in enhancing the shark’s camouflage via countershading. By being able to dynamically adjust the darkness or lightness of its top and underside, great white sharks can more effectively match their surroundings and light conditions, thus improving stealth when hunting or avoiding detection.
This camouflage strategy is not exclusive to the great white shark. Some planes, particularly those from World War II, are painted lighter underneath for similar camouflage purposes. An object with countershading will appear flat and indistinguishable at a short distance when seen against a background of similar color and pattern, making it harder for targets to visually discern the object's location.
In summary, the real-time color change in great white sharks involves hormonal regulation of structural coloration through specialized skin denticles, enhancing their countershading camouflage to better blend with the environment and reduce visibility to prey and predators. This fascinating adaptation is a testament to the shark's incredible ability to adapt and thrive in its aquatic habitat.
- The color changes in great white sharks can happen in real time, as discovered by Michelle Jewell in 2022, and are facilitated by hormonal mechanisms, such as adrenaline and melanocyte-stimulating hormone (MSH).
- In the field of science, particularly biology and ecology, the countershading phenomenon observed in great white sharks is closely studied for its adaptive significance in evading detection.
- Researchers in health-and-wellness, fitness-and-exercise, and sports fields can draw parallels between camouflage techniques, like countershading, and the strategies athletes use to blend into and perform optimally in their respective environments.
- Just like the anti-UV property of great white sharks' skin, modern-day products in the sphere of health-and-wellness are often created with the goal of enhancing an individual's adaptability and resistance to different conditions.
- The evolving understanding of great white shark camouflage through countershading can provide exciting research opportunities for good-and-wellness, fitness-and-exercise, sports, and mixed-martial-arts industries, fostering development in material science and facilitating the creation of adaptive, environment-friendly protective gear for athletes and practitioners.
