The Desert Biome & Its Inhabitants
The purpose of this post is to explain and show, how numerous species that are unique can regulate on their own their body temperature, when the temperature of nature does not conform on their needs.
My partner (crushgrl101) and I decided to compare how temperature regulations differ between plants and animals. Before we proceed, we first must ask what is thermo-regulation. By definition, directly from our class, it is how animals or plants that live in different environments regulate heat and stabalize it. Since we are studying species that survive in extreme temperatures, they acclimate, which is, by definition, the physiological (not genetic) change and response to environmental temperature (D. Grekinis, ppt).
The plant species we chose is a small type of gourd, known as the Alkhad (Citrullus colocynthis). It is the size of a melon and it can be found in a desert-based biome, specifically the Sahara Desert. It is commonly spotted around countries that border the Mediterranean Sea, such as Libya, Israel, and Turkey. According to the information found in the reference section, if consumed in high amounts, the Alkhad plant can cause abortions. Below, you can see a picture of the Alkhad plant: http://www.temehu.com/Wild-life-in-sahara.htm.
The average temperature in the desert can shoot past 38˚C, the highest on record, at 58˚C, being in Libya during the year of 1922. There is little to no rainfall throughout the year and drought is a natural problem. According to our personal experiences, neither of us have been to a country surrounded by desert, but, despite that we are curious to see why and how animals and plants can survive in 136˚ F heat!
The animal species we picked is the Dorcas Gazelle (Gazella dorcas). It is a unique creature – it has long ears and curved horns, with a pale-red fur coat with white on its underbelly. It lives throughout Northern Africa and around the Red Sea.To your left, you will see a picture of the Dorcas Gazelles (http://www.shoarns.com/DorcasGazelle.html). It has adapted so well to its desert environment, the Dorcas Gazelle can survive its entire life without drinking water because it sustains itself with moisture from the plants that it lives off of. We chose this animal for two reasons: (1) because it lives in the same biome as the Alkhad (making it easier to compare the two), and (2)we have never seen a Gazelle before.
Also, you can see how the Dorcas Gazelle live in the desert and survive:
The Alkhad plant and the Dorcas Gazelle, both thriving, despite living in the largest desert in the world, must maintain a cool body temperature through the day and warmth at night. We will discuss how the species survives through thermoregulation in the next paragraph, with reference to notes and our textbook. If either species failed to do this, then they would surely parish to the unmerciful heat. Moreover, the challenges of these two creatures are adopt to scarce rainfall and, for the plant, to find soil rich in nutrient, and the animal to find enough moisture in the plants that consumes.
Ways & Strategies Maintaining Body Temperature
To start, the Alkhad plant, being from the desert, does not have a need to rely on heat from metabolism (Hm) and heat from evaporation (He), so, when crossing out those factors, it only uses Hs=Hcd+/-Hcv+/-Hr . Our ecology book sums it up when it states that “to avoid heating, plants in hot deserts have three main options: decreasing heating by conduction, (Hcd), increasing rates of convection cooling, (Hcv), and reducing rates of radiative heating, (Hr)” (Molles, pg. 111). With this in mind, we can understand that both plants and animals can regulate their temperature.
The Dorcas Gazelle uses the same formula, but places an emphasis more on heat obtained from metabolism than evaporation and radiation. So, the normal endothermic animal would be using an equation like this: Hs=Hm+/-Hcd+/-Hcv+/-Hr-He. As you can see, we added back in the loss of heat through evaporation (via sweat), as well as the heat gain/loss from metabolism.
the right, you can see how plants and animals adapt to the desert: http://www.vtaide.com/png/foodweb/desert-sm.jpg .
While researching ways that plants and animals thermo-regulate, we consulted our textbook (Molles, pg. 115-117), which went into detail about the heat exchange and the counter-current heat exchange. The author mentioned how dolphins survive oceanic temperatures by conserving heat through the countercurrent heat exchange. In our class discussion and from our textbook (Molles, pg. 116), we can say that countercurrent heat exchange takes place when, for example, blood vessels “collaborate” with one another, passing around heat to avoid having heat escape from the cells of the body. Comparing this concept to heat exchange, we can mention that, when two species come into contact with one another they transfer heat. The species with the higher heat capacity exchanges more heat to the other creature, which explains why an egg fries in a pan.
Normally, plants, such as the ALkhad, use photosynthesis in order to regulate heat and gases through its cells, by means of opening and closing the stomata found in the cell membranes. In other words, the plant can stop light and heat from entering or exiting the “body”, as well as mentaining its scarce water supply. Another factor that plays a major role in the survival of Alkhad is the color of the ground. Why is this? Simple. Because, when light particles are absorbed by different colored items, such as the sands of white and black beaches referred to in our book (Molles, pg. 103), they reflect off the ground, adding heat to anything it touches, including the Alkhad. Luckily, plants get their moisture from the roots, which expand and search for underground water. Last but not least, is how the Alkhad’s leaves expand and contract, while following the sun’s movements in the sky. By this, we mean that the plant conserves its water supplies by wrinkling its leaves and continuing photosynthesis thoughtout the day by following the sun.
Animals, specifically mammals, on the other hand, rely heavily on the heat consumed by metabolism, simply because, as mammals are active, they consume more energy, therefore they need heat to support their lifestyle. The Dorcas Gazelles is acting in this manner. As a consequence, the Dorcas Gazelles consume a huge amount of food as a replacement for their water supplies. Therefore, they do not have to drink water, because they rely so heavily on the moisture found in their food. This is how they have adapted as a species and survived in dry, desert-like conditions. Furthermore, the Dorcas Gazelles have mastered the ability to limit perspiration by evaporation. In order to avoid sweating, they reduce their physical activities and head toward shade, food, and water. Finally, because the Dorcas Gazelles have hooves under their feet, they are protected from the harsh elements, such as heat rising from the ground.On the left, there is a picture of how heat is conducting: http://biology.clc.uc.edu/graphics/bio303/water%20cycle.jpg .
It’s vitally important for both the plant and animal species that live in any area with extreme temperatures (high and low) to regulate and stabilize their heat. If not and the body cannot compensate and balance out the temperatures running through the body, then the animal or plant will die. For animals, especially endothermic animals, regulating temperature through instinctive behavior, such as muscle contractions, shivering/ goose bumps, sweating, etc, saves lives. As far as the Dorcas Gazelles is concerned, we can see that regulating body temperature limits conserves water and saves the animal from potential problems. Plants, on the other hand, must adapt through the use of their roots, leaves and fertilization habits. The Alkhad plant produces more than enough seeds to survive the growing season.
- Molles, M.C. (2010). Ecology. Concepts and Applications. 5th Ed. NY: McGraw-Hill.
- “Temehu: Wildlife in the Sahara” (n.d.). Retrieved October 17th from http://www.temehu.com/Wild-life-in-sahara.htm.
- Burghardt, James. “Native Plants in Libya” (n.d.). Retrieved October 17th from http://www.gardenguides.com/123439-native-plants-libya.html.
- “Colocynth” (n.d.). Retrieved October 17th from http://en.wikipedia.org/wiki/Colocynth.
- Sharp, Jay. “The Sahara Desert: Geography and Climate” (n.d.). Retrieved October 17th from http://www.desertusa.com/du_sahara.html.
- Huffman, Brent. (2004). “Gazella Dorcas”. Retrieved October 17th from http://www.ultimateungulate.com/artiodactyla/gazella_dorcas.html.
- “Dorcas Gazelle” (n.d.). Retrieved October 17th from http://en.wikipedia.org/wiki/Dorcas_Gazelle.
- Food webs” (n.d.). Retrieved October 18th from: http://www.vtaide.com/png/foodweb/desert-sm.jpg
- “Water Cycle” (n.d.). Retrieved October 18th from http://biology.clc.uc.edu/graphics/bio303/water%20cycle.jpg
My partner is Crushgrl101.wordpress.com .