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Running head: AN EVALUATION OF THE ELEPHANT An Evaluation of the Elephant Compared to Modern Domesticated Species Karianna Gooding Broadview University 1 AN EVALUATION OF THE ELEPHANT 2 Abstract This essay will cover the following anatomical structures of the pachyderm: the musculoskeletal, digestive, circulatory, respiratory, urinary, reproductive, and integumentary systems and some interesting facts about the pachyderm’s behavior social system. Along with completing an evaluation of the structure and function of each section of the elephant’s body, a compare and contrast between the pachyderm and the canine, feline, bovine, and equine species will also provide a unique guide to allowing the reader to visualize how unique the pachyderm is and how evolution specialized this animal to its environment. AN EVALUATION OF THE ELEPHANT 3 An Evaluation of the Elephant Compared to Modern Domesticated Species Biodiversity within the animal kingdom is as abundant as it is complex. This becomes more and more evident as one delves into the veterinary and zoological sciences. These fields of study offer the basic knowledge needed to classify and evaluate the multitude of organisms found within the kingdom Animalia. With one’s knowledge of the diversity and likenesses with the animals and their body systems, we can begin to understand what truly makes each species unique. With that given, our purpose here will be to compare and contrast modern day domestic species such as the bovine, equine, canine, and feline to the pachyderm. The animals’ systems have likenesses by are different in various and interesting ways as a byproduct of each species’ evolution and speciation for its environment. The following evaluation will focus on: the musculoskeletal, digestive, circulatory, respiratory, urinary, reproductive, and integumentary systems and some interesting facts about the pachyderm’s behavior social system. The first topic of discussion between the animals is the musculoskeletal system. In every animal, the musculoskeletal system is the basic means for movement and support for the body. Over two hundred bones comprise the entire skeletal system for the elephant (“Elephants move like,” 2010). As a whole, the entire skeleton of the elephant is approximately 16.5 percent of the entire weight of the animal’s possible two ton frame. This main support system for the massive body is its appendicular skeleton, which includes its thoracic and pelvic limbs. The legs of the elephant are more vertical in position than the angular limbs of the other quadrupeds, offering an almost pillar like support for the enormous weight of the animal. Additionally, in the elephant’s long bones, there is a lack of any marrow cavity which allows for stronger bones able to withstand more pressure (“Elephant anatomy and,” n.d.). Conversely, if one has ever seen an elephant walk, they appear to be flat-footed; however, much like the equine and bovine, the AN EVALUATION OF THE ELEPHANT 4 elephant walks on its tiptoes compared to a feline or canine which walks on its pads. It is noted that the pad of an elephant is as diverse as the human fingerprint in that it is unique to that particular animal; the pattern of the print can also be used to determine the age and overall size of the elephant as well. Interestingly, the musculoskeletal system of the elephant allows it equal power over all four limbs in an almost four by four function; other quadruped animals are only known to power from their hind legs for acceleration (“Elephants move like,” 2010). This essentially provides the elephant with great power for the locomotion of its massive frame. The muscle system of the elephant as a whole is literally larger than most other species, from the length and size of the muscle, to the size of the fibers that comprise the muscles themselves. Comparatively, the main body bone structure of the elephant is much like any other mammal with 19 to 20 pairs of ribs and a Cervical: 7, Thoracic: 20, Lumbar: 5, Sacral: 5, and then a 24 to 33 tail vertebral pattern depending on the species. The elephant’s skull is very large by also lightweight because of the pneumatization of the cranium; in other animals, only the sinus cavities are pneumatic. The elephant’s most noticeable form of speciation is evident with its large trunk. It has be thought to have evolved from fused muscles of the nose, upper lip, and cheek. The trunk of the elephant has no bones but contains over 40,000 muscles divided into as many as 150,000 individual units. The trunk contains both superficial and internal muscles. The superficial muscles run longitudinally along dorsal ventral lateral aspects. The internal muscles include radial and transverse muscles allowing the trunk to be as specialized as a finger but strong enough to lift around 770 pounds (“Elephant anatomy and,” n.d.). One of the most important functions of the elephant trunk is that it is a major structure of the respiratory system of the animal. Within most mammals, there is a pleural cavity which contains the lungs. The pleura usually aid an animal with breathing by exerting negative AN EVALUATION OF THE ELEPHANT 5 pressure on the lungs forcing them to expand for a breath. However, elephants do not have a pleural cavity within their body. Because of this, the elephant’s lungs are connected directly to the chest cavity wall, and the diaphragm and breathing is done so by flexing and relaxing of the chest muscles. The elephant’s ability to breathe is still an autonomic function; yet, due to the respiratory structure, if excessive pressure is applied to the chest cavity of the animal, it will likely suffocate. Amazingly, even with this unique respiratory structure, the elephant can still breathe an astounding 310 liters of air every minute. The internal structure of the elephant’s lungs are larger than smaller species and allow the alveoli to situate in such a way that the sheer weight of the animal and gravity do not offer any resistance to proper breathing and oxygenation. Like all mammals, airflow come in through the mouth and the nostril to the nares and down the trachea into the lungs; then the opposite occurs for respiration. The speciation of the trunk allows it not only breathe for the animal, but it can also hold liquids and food with in it without interruption of respiration (“Elephant respiratory system, n.d.). Even though the trunk of an elephant can used to hold liquids or aid in eating, the elephant cannot drink or eat directly through it. The elephant can only use its trunk to squirt liquid and put food into its mouth where it can be masticated and swallowed. When comparing digestive systems to other mammals, the elephant has a system much like that of a horse or zebra allowing it to be known as a non-ruminant mega herbivore. Through the elephant’s life time, they can have six sets of molars. At any one time, all that is possessed for mastication are just four large teeth: two in the upper jaw and two in the lower. The movement of the elephant’s teeth is unique in in that they do not completely shed their milk teeth; rather, the anterior teeth are the old, worn teeth while the posterior molars are the new teeth. Unfortunately, because of this unique way of tooth movement and the elephant’s fibrous diet, many elephants’ last set of AN EVALUATION OF THE ELEPHANT 6 teeth wear out around age sixty, and if they are not able to adjust their diet, they starve to death. Interestingly, the animals’ well known large tusks are actually lateral incisors that grow continuously throughout the animal’s lifetime at an average rate of 15 to 20 centimeters per year. Instead for mastication, the tusks are used for fighting, digging, carrying, and debarking trees (“Elephant anatomy and,” n.d.). Sadly, because of their size and unique composition, elephant tusks have been the target of poachers and ivory dealers for centuries, in which the animal is often killed for goods. After the food is chewed by the animal, it passes through the esophagus and down into the stomach. The elephant’s digestive system functions much like any other mammal with the main difference being the massive size of each organ respectively. Due to this massive size, the maximum capacity of their stomach is around 76 liters, and due to their unique diet, they are prolific saliva producers in order to process the mass of fibrous nutrients into the stomach. Their stomachs are actually cylindrical in shape with the middle of the organ remain more glandular in shape. From the stomach the food is processed into the intestines, which can actually reach a length of 19 meters. Because the animal is an herbivore, the intestine is where most of the digestion actually will take places, where bacteria in the sacks of the caecum are used to ferment and break down the hard to digest cellulose and aid in the absorption of most of the water and nutrients. Because of the animal’s diet, the elephant only can benefit from around 40 percent of its entire intake turning the rest into feces and urine, ultimately requiring the animal to forage and eat 24 hours a day and consume up to 240 kilograms of food relative to its size (“Elephant anatomy and,” n.d.). Interestingly enough, the elephant’s urinary system functions much like ours; the main differences lie within the unique size and shapes of the organs. The kidneys in the elephant AN EVALUATION OF THE ELEPHANT 7 contain eight lobes, and the left kidney is more caudal than the right. Much of the animal’s other urinary tract functions are similar to other mammals, but the elephant can release up to 50 liters of urine daily depending on their intake. Their urine is usually clear to straw like in color and almost always alkaline in pH. An elephant’s urine contains uric acid with about two grams of the animal’s urine containing minerals and organic solids. Additionally, the elephant typically has low serum blood urea nitrogen values. Like any other mammal, the elephant is susceptible to urinary tract diseases and conditions that may even compromise the animal’s reproductive system in the process (Murray & Fowler, 20116). Unlike most mammals, the testicles of the elephant are located within the body close to the kidneys. The male reproductive system is about two meters long, and the males usually become sexually mature around 10 to 15 years of age. Periodically, males go through a period of high testosterone production musth. This results in high aggression and is recognized by the presence of fluid behind the elephant’s eyes and patches of urine on the elephant’s skin. Male elephants actually test a female’s ability for reproduction by sampling the female’s urine on the roof of their mouth. Female elephants typically can reproduce beginning around 12 to 15 years of age, and if the cow becomes pregnant, the gestation period is about 21 to 23 months with at least a five year period between births to raise the youths. Calves are born fully functional and ready to walk once the animal’s nervous systems recover from the initial shock of birth (“Elephant reproduction,” 2009). Like within most mammals, the brain, spinal cord, and peripheral nerves make up the animal’s central nervous system. Most are aware that the elephant is a very intelligent animal, and the brain of the elephant is the largest among all other land animals on earth; yet, interestingly, their brain is actually quite small in reference to its massive size. With male AN EVALUATION OF THE ELEPHANT 8 elephants, the brain usually weights about 4.2 to 4.5 kilograms and about 3.6 to 4.2 kilograms within the average female. Yet, there has never been any noticeable difference between males and females of any elephant species recorded to this date. However, this may be to the fact that much of the current data in the field of research is rather old, dating back to the 19th century in fact, and information is usually difficult to trace (Bull, 2001). This is why very recently scientists are beginning to study this topic again for further understanding. It is now known that the elephant is in fact one of the most intelligent animals; it is mainly due to a highly developed and complex pattern of gyri and sulci. The main differences associated with the elephant spinal cord are two enlargements: one cervical and one lumbar. These enlargements are specifically there because they are rich in nerve cells; this is something that is extremely important for the animal’s ability to power and drive their massive limbs (“Elephant anatomy and,” n.d.). The peripheral nervous system gives elephants a moderate sense of sight, but a very well developed sense of hearing, smell, and touch. Elephants have very good hearing and can detect sounds as low as 14 to 16 hertz and up to 12,000 hertz. It has been believed, that the common elephant can hear the lower frequency sounds of other elephants from up to 0.9 miles away thanks to the animal’s uniquely large ears. The olfactory senses of the elephant are just as powerful. They can smell sources from up to 12 miles away, and if that is not enough, elephants have a special sensory organ known as the Jacobson’s organ located on the upper palate. This organ is attached to the mouth through the nasal passage way and acts as a special chemical receptor site for additional sensory information. Even the animal’s sense of touch is highly developed, allowing it to detect pressures as shallow as 0.1 inches into its body. However, the most interesting part of the animal’s sensory system is its ability to detect minute seismic vibrations through special sensing membranes called pacinian corpuscles. These corpuscles are AN EVALUATION OF THE ELEPHANT 9 made of layers of connective tissue under the animal’s skill that can be compared to the layers of an onion. These layers contain a slimy gel between them that, when a vibration is felt, causes a deformity within the corpuscle that stimulates the nerves directly. Amazingly, it is thought that elephants survived the Asian tsunami of 2004 because this specialization of their sense of touch gave them an advanced warning of danger because they were able to feel the seismic disturbances well ahead of time (“Elephants senses,” n.d.). Due to the massive size of the elephant, it’s equally massive limbs and body systems mean that it requires a heart and circulatory system to keep the animal alive. The heart of the elephant usually eights anywhere between 12 to 21 kilograms and has an apple like shape containing double ventricular apices. Large sinuses within the heart are able to sustain the high blood pressure needed to maintain circulation and aid in the cardiac contraction to prevent any damage that may be done to the peripheral blood vessels. The sinuses are found on both sides of the temporal area along the sternum, trachea, axillae, and inguinal areas. Interestingly, due to the sheer weight of the animal, the vasculature of the vessels are stronger and thicker walled then that which can be found in almost any other mammal. Blood composition within the elephant is similar to any other mammal, with the exception of the blood cells are actually larger to carry enough oxygen to keep the animal alive (“Elephant anatomy and,” n.d.). Lastly, the elephant’s integumentary system acts just like that of any other mammals. However, skin thickness is not equal throughout the body. The skin on the elephant can be up to 2.5 to 3.5 centimeters thick on its back and buttocks and only 1.8 millimeters thick on areas such as the ear, around the mouth, and around the animal’s anus. Again, like most mammals, the elephant’s skin is comprised of two layers: the dermis and epidermis and still contains hair follicles and glands connected to a very rich nerve supply. Skin colors can be brown to reddish, AN EVALUATION OF THE ELEPHANT 10 like in African elephants and grey in Asian elephants. Elephants are not very hairy animals; adults have less hair than calves and African elephants actually have less hair than Asian elephants. The hairs concentrate around the end of the tail and around the mouth, ears, chin, and eyes for extra protection. The elephant actually lacks sweat glands over the majority of its body: therefore, they cannot be used for regulation of body temperature. Their main means of thermoregulation are utilized by the massive surface area of the ears, which is used to radiate heat outwards away from the animal, which is why it is common to see an elephant constantly flapping its ears as a means to increase the heat radiation. An altered sebaceous gland known as the musth is part of this system. The gland is located between the eye and ear of the animal and is a very important gland for the animal’s reproductive system as mentioned earlier (“Elephants anatomy and,” n.d.). As one can clearly see, the elephant is a very unique mammal within the animal kingdom. The similarities between the animal and the other aforementioned species are often very subtle compared to the obvious differences noted. Yet, even though the elephant is a massive, mostly peaceful, and very intelligent animal, it is still very specialized and highly evolved to live within its environment. In order to keep this animal as one of the most unique on earth, people strive every day to further understand, help maintain and conserve the animal’s habitat, and ensure the animal’s safety. Although the elephant populations still live in captivity to this day, go out, explore, and learn about this interesting animal. Ensure that future generations are able to see this amazing animal thrive and remain the way that they are meant to be. AN EVALUATION OF THE ELEPHANT 11 References Bull, B. An overview of the central nervous system of the elephant through a critical appraisal of the literature published in the XIX and XX centuries. Chicago: Cozzi Spagnoli, Bruno Zooi. Elephant anatomy and physiology. (n.d.). ANCF. Retrieved from http://www.asiannature.org/know-elephant/elephant-anatomy-and-physiology Elephants are amazing! (n.d.). Association of Zoos and Aquariums Elephant Taxon Advisory Group & Species Survival Plan. Retrieved form http://elephanttag.org/General/general_home.html Elephant reproduction. (2010, June). Association of Zoos and Aquariums Elephant Taxon Advisory Group & Species Survival Plan. Retrieved from http://elephanttag.org/General/general_elephant_reproduction.html Elephant respiratory system. (n.d.) Elephants forever. Retrieved from http://www.elephantsforever.co.za/elephants-respiratory-system.html Elephants move like 4x4s: Scientists. (2010, March 30). Phys.org. Retrieved from http://phys.org/news189160019.html Elephants senses. (n.d.). SeaWorld Parks and Entertainment. Retrieved from http://seaworld.org/animal-info/animal-infobooks/elephants/senses/ Murray, E., & Fowler, S. K. (2006). Chapter 29 urinary system. In S. K. Murray, & E. Fowler, Biology, medicine, and surgery of elephants (p. 398). Ames, IA: Blackwell Publishing.