Table of contents
- The Cardiovascular System of the Giraffe
- The Nervous and Skeletal Systems of the Giraffe
- The Reproductive System of the Giraffe
- The Respiratory System of the Giraffe
- Cryopreservation Study Being Conducted on Giraffes
- Recent Research Supporting Four Species of Giraffes
- Comparison Between Giraffes and Animals Dissected in Lab
What do you get when two giraffes collide? A giraffic jam. The giraffe’s elongated shape and rather large body size causes it to have some unique aspects. Some of these aspects can be seen in some of their organ systems, such as the cardiovascular and respiratory systems. These exclusive aspects also make the giraffe very different in many ways when compared to the animals dissected in the laboratory. Because of this distinctiveness, there are always new and current studies being done on giraffes to develop a better understanding of them and how they function. Some of these studies includes testing giraffe sperm in ultra-rapid freezing cryopreservation to determine if it is possible to genetically help reproduction in a controlled environment and conducting multi-locus analysis to determine the true amount of species of giraffes there are. First, some of the unique aspects of the many organ systems of the giraffe will be discussed.
The Cardiovascular System of the Giraffe
A giraffe has some organ systems that aren’t like any other living creature on earth. This is because of their elongated shape, which affects their structure and how things function inside their bodies. For starters, giraffes have an extraordinarily unique cardiovascular system. Giraffes have an exceptionally high blood pressure when compared to humans (Gaitan, 2015). This could cause plenty of problems for them internally. They have four mechanisms inside that help prevent those problems from occurring. The first mechanism is their jugular valves that prevent blood from flowing back into their jugular vein when they tilt their head down. It essentially keeps the blood from rushing to their heads. Giraffes also have a built in ‘G-suit’, which is a flight suit worn by aviators and astronauts that prevents deprivation of blood to the brain while flying. This built in ‘G-suit’ prevents leakages due to hypertension from the capillaries in their legs. The last two mechanisms are the rete mirabile and complex series of mechanisms that prevent too much or too little blood flow to the head.
In addition to the high blood pressure, giraffes have extremely strong hearts. “In order for the heart to pump the blood up the carotid artery to the brain, the heart must be strong enough and be able to overcome the hydrostatic, or pressure due to gravity” (Gaitan, 2015). This strength comes from the structure of their hearts, which is determined by a giraffe’s neck length. A part of this strengthening structure is the left ventricle in the heart. A giraffe’s left ventricle has more hypertrophy, or thickness, to it than most living creatures because of the length of their necks and how hard it has to work to get blood to the brain. As a giraffe’s neck grows, this thickness increases.
The Nervous and Skeletal Systems of the Giraffe
Two more unique organ systems of the giraffe are the nervous system and the skeletal system. The brain of the giraffe is comparable to other terrestrial Cetartiodactyla without the rotations and compressions found in more distant Cetartiodactyla such as the bottlenose dolphin. It also shows a high degree of gyrification, which is the process of forming folds of the cerebral cortex. In other words, a giraffe’s brain is very developed, and it suggests surface enhancement in a relatively smaller space compared to species with a similar brain weight. As for the skeletal system, giraffes have a very special first thoracic vertebra in their necks. It “provides higher flexibility to the neck and may provide advantages for high browsing and/or male competition behaviors specific to giraffes” (Gunji, Endo, 2016).
The Reproductive System of the Giraffe
Another organ system that has a distinctive characteristic for the giraffe is the reproductive system. “Giraffes are one of the few species of large mammals capable of directly nurturing two individuals of different ages: one a fetus and one a rapidly growing young calf” (Deacon et al., 2015). Speculated traits of the giraffe that may have an effect on their unusual reproductive abilities occurring include “non-seasonal breeding, slow embryonic development and rapid calf growth” (Deacon et al., 2015). In the even that this unusual ability occurs for a female giraffe, there are some great reproductive costs for her, which means that reproduction is costly to an organism in terms of its future survival and reproduction, when it does happen to occur. This ability to be, or get, pregnant and still be nursing a new-born calf causes “increased nutritional demands upon females” (Deacon et al., 2015). An increased nutritional demand could then cause a physical strain.
The Respiratory System of the Giraffe
Last, and certainly not the least, unique organ system of the giraffe is the respiratory system. There has been no noted sighting of a giraffe panting. This is because of their peculiar respiratory system mechanics and narrow trachea that make it impossible for them to do so even for short periods (Mitchell, Skinner, 2004). Something else that is special to the giraffe’s respiratory system is that their long necks contain long tracheas and this means a large respiratory dead-space, which is a volume of breathing that does not exchange gases (Harrison, 1980). Their dead-space is approximately nine times greater than humans’ and their total lung capacity about eight times larger than humans' (Harrison, 1980).
Cryopreservation Study Being Conducted on Giraffes
A new, or more recent, study that is being conducted on giraffes, and many other animals, is ultra-rapid freezing cryopreservation of sperm from endangered species. This study has been tested on multiple endangered or becoming endangered species, similar to the giraffe. Some background of the study includes the process of cryopreservation, which is the ultra-low temperature storage of living cells, tissues and organs capable of resuming normal functions after retrieval from a cryobank (Day et al., 2008). The ultra-rapid freezing part of involves rapid cooling of small samples that do not involve no permeating cryoprotectant, which is recommended for cryopreservation of sperm in giraffes.
The study found, conducted by Obrien et al., was the first study of its kind on giraffes. The results of the study were relatively promising. Values for the studied sperm variables declined after freezing-thawing, and epididymal samples always returned better results, suggesting that these sperms to be more cryo-resistant than ejaculated sperm (Obrien et al., 2019). This means that there is some promise to the study, and eventually there might actually be a way to help endangered species, like the giraffe, reproduce in a controlled environment.
Recent Research Supporting Four Species of Giraffes
For many years, it was originally believed that there was only one true species of giraffes with around nine or eleven different subspecies. In a study conducted in 2016 by Fennessy et al., “Coalescence-based multi-locus and population genetic analyses identified at least four separate and monophyletic clades, which should be recognized as four distinct giraffe species under the genetic isolation criterion”. This was the first study of its kind of analyzed nuclear gene data done of giraffes, proving that some formerly recognized subspecies were actually genetically identical, suggesting that they all belonged as one species.
The results of the study, conducted by Fennessy and colleagues, showed that there was reproductive isolated between the newly discovered four species of giraffes. This was indicated, or supported, by the “concordance between maternally inherited mitochondrial and biparentally inherited nuclear markers” (Fennessy et al., 2016). Resulting data from this study has also contributed to further conversation research on two of the four species of giraffes due to the discovery of the newly found genomes for them. So, instead of one species with multiple subspecies, there are four genetically different species of giraffes. These four species of giraffes consist of the following: the southern giraffe, which includes what used to be the two subspecies of the Angolan and South African giraffes, the Masai giraffe, which includes the former Thornicroft’s giraffe, the reticulated giraffe, and the northern giraffe, which includes what used to be the four subspecies of the Nubian, Rothschild’s, Kordofan, and West African giraffes.
Comparison Between Giraffes and Animals Dissected in Lab
As for the comparison to the animals dissected in the laboratory, the giraffe is a relatively large animal compared to all of the dissected animals. This would make it extremely difficult to dissect if wanted to, even if the giraffe was still a baby. Their babies are still a much larger scale than the rat or pigeon dissected in the lab. Though, if one wished to dissect a giraffe, it would be a lot easier to see and examine all of the different organ systems. It would also be a lot more difficult to destroy or tear an organ on accident while dissecting owing to the fact of their large-scale body size. Most of the animals dissected in lab are relatively small and it is hard to see all of the organ systems without accidentally ruining one or more of the organs.
Another area that is different between the giraffe and all of the animals dissected in the laboratory is that the giraffe has a lot of distinctive aspects to their organ systems that no other animal has. This means that there would be a lot of benefits in dissecting a giraffe due to the fact of how different it is from the normally dissected animals. Giraffes are also way more exotic than any of the animals dissected in the lab. Most of those animals are local animals that could be found around American wildlife and oceans. Giraffes, on the other hand, live in Africa, and the only way they are seen in America are in zoos or sanctuaries for endangered species.
Because of the long, stretched-out shape and large body of the giraffe, it has unique aspects to make sure that everything inside is working like it should. These differences can be greatly seen in many of the giraffe’s organ systems and also make them differ greatly from the animals dissected in the lab. To develop a better understanding of the distinctive aspects of the giraffe, there are also always new and current studies being done on them, such as the ultra-rapid freezing cryopreservation of their sperm and multi-locus analysis. Overall, the giraffe is an incredibly, extraordinary creature that is still being learned from today.