Camels – Adaptations to Extreme Environments
The Camel: How it has Adapted Organisms exist in many environments, some are arid, some flooded, some are basic, some acidic, some are hot, and some are cool. Regardless of the conditions, animals have adapted themselves to survive in their surroundings. One of the main ecosystems that is classed as an extreme environment is the desert ecosystem. A classic example of a desert is the Sahara. Aridity is a characteristic shared amongst all deserts. As reported by Smith (2013), the reason most deserts are arid is because of uneven levels of evapotranspiration and precipitation.
Aswel as adapting to very dry conditions, organisms in a desert ecosystem have also adapted to hot temperatures. The temperatures range from as high as 40oC during the day to as low as below freezing during the night due to lack of cloud cover. Evolution: As wrote by Long & Savage (1986) in the late Eocene period and to the end of Miocene, camels evolved and diversified solely in North America. During this time they were similar in size to rabbits, and their feet contained four toes. In Oligocene times, camels were similar in size to goats, with the lost of the lateral toes, with the remaining digits showing signs of evolution.
During the Miocene time, camels adapted a new of walking, it is know as pacing gait. This is where the camel moved both left or both right legs in one movement, instead of opposite legs. During this time camels feet produced pad like structures, which helped them from sinking in soft terrain i. e sand. Then they arrived in South America during the Plio-Pleistocene times. This is where they diversified into 2 more genus under Camelinae family of the more known species, llama and alpaca, and 2 less known, guanaco and vicuna.
As this happened, they crossed into the ‘Old World’, where they then spread across Europe, Asia and Africa, this is where they branched out into the ‘single humped’ Camelus Dromedarius, and ‘double humped’ Camelus Bactrianus. Characteristics of Camelus Dromedarius: An animal that has adapted well to this environment is the Camelus Dromedarius. Wilson (1984) as cited by Kohler-Rollefson (1991) describes the features of the camels body. Dromedary camels have a shoulder height of at least 1. 8m, with the hump extending a further 20cm. They can weights upwards of 400kg.
Dromedary camels have a long upward curved neck, with a single hump on it’s back. This is all supported by their long, strong legs and wide webbed feet. Body Temperature / Water Conservation: In the desert temperatures fluctuate. On average, a dehydrated camels body temperature fluctuates by up to 8oC in a single day, it can increase from an average of 34-36 to 42oC. There is less of a fluctuation if the camel is hydrated (2oC). If camels did not tolerate this fluctuation in temperature and instead tried to keep the body cool, up to 5 litres of water could be lost due to sweating.
This allows the camel to conserve water and energy. The camel then takes advantage of the cool evenings to dissipate heat, with no energy cost. Camels, like all other mammals do sweat to maintain an acceptable temperature, however, it is not continuous. (Mares, 1999). Composition of Camel’s Hump: Mares (1999), reports that a common misconception associated with camels is that their hump is composed of water, this has been disproven, and instead replaced with the fact this it is fat. Another common misconception associated with a camels hump is that water is produced by the oxidation of fat.
This is has been proven to be false, or at least, partially untrue as the oxidation of fat requires an increased oxygen intake, this results in an increased rate of breathing, which increases the amount of water lost as vapour from the lungs. This nullifies the effect of the metabolized fat, yielding no net gain in water. As previously discussed, camels have adapted to keep their bodies cool, without sacrificing water. Another adaptation that is seen with camels is that their main fat store is their hump. A camel does not store fat on other parts of their body.
This is because the fat would act as insulation and reduce the amount of heat lost at night, at a time when the temperature is cooler, and most heat dissipation occurs. Excretion in Camels: Richards (1973) as cited by Mukasa-Mugerwa (1981) explores the fact that camels are able to produce urine that contains twice as much salt as sea water. It was noted by Mukasa-Mugerwa (1981) that the Kidney is composed of Henle loops of varying lengths. Camels are seen to contain a lot of longer loops than any other species, so there is a bigger potential for water to be reabsorbed, and the urine becoming concentrated.
This coincides with the camels ability to facilitate water and plants with a salt content higher than normal. Schmidt-Nielsen (1964) as cited by Mukasa-Mugerwa (1981) compared the volume of urine excreted by the camel while hydrated and while dehydrated. The camel while hydrated, excreted up to 4 litres of urine in a single day, compared to the when it was dehydrated, where it excreted up to half a litre of urine. It was also noted that the camel produced faeces, almost completely absent of water.
It was composed of a large number of pellets approximately 3cm in length. As they lacked water, they were light to lift, with a shiny appearance. Conclusion: Camels like animals in other extreme environments have adapted well to suit their environment of temperature fluctuations and a lack of water. Camels have evolved in such a way that moving has been made easier, they do not sink into the sand, so they do not expend more energy than is needed. The camels adaptation to a large fluctuation in body temperature allows water to be conserved as it is not lost as sweat.
The camels hump proves as an invaluable energy source when food sources are scarce, as is common in desert ecosystems, the fat is metabolized and used as energy. It’s all these adaptations that allows the camel to live in such an extreme environment. The absence of one or more of these adaptations would lead to the inability of camels to survive in this environment. In this day and age global warming is increasing the average temperature of the earths atmosphere, if there was a significant increase, could these organism handle an increased temperature luctuation? References: Jeremy M. B. Smith desert 2013. Encyclop? dia Britannica Online. Retrieved 01 March, 2013, from http://www. britannica. com/EBchecked/topic/158992/desert Kohler-Rollefson, Ilse U, (1991). Camelus Dromedarius. Mammalian Species. 375 (1-8), pp. 1-4 Mares, Michael A. , (1999). Encyclopaedia of Deserts. 1st ed. Oklahoma: University of Oklahoma Press. Richards, S. A. , 1973. Adaptation to heat. In Temperature regulation. London, Wykeham Publications, pp. 191-197 as cited by Mukasa-Mugerwa, E. , (1981).
The Camel (Camelus Dromedarius): A Bibliographical Review. 1st ed. Ethiopia: International Livestock Centre of Africa Savage R. J. G & Long, M. R. , (1986). Mammal Evolution. 1st ed. United Kingdom: Facts on File & The British Museum. Schmidt-Nielsen, K. 1964. The Camel. In Desert Animals: physiological problems of heat and water. Oxford, Clarendon press, 277 pp as cited by Mukasa-Mugerwa, E. , (1981). The Camel (Camelus Dromedarius): A Bibliographical Review. 1st ed. Ethiopia: International Livestock Centre of Africa
