Individual reflection - Chia Wei Qian

What was the most interesting proposed used of biomimicry that was developed in blog? Why?

There are a lot of people having pets in their own life as their greatest partner, family member, soulmate or best friends. Mostly people pets choices are mammals like puppy or kitten and there's also less favorable amphibian such as fresh water turtles. It is a very good experience for us to has a chance to adopt a fresh water turtle as a pet and biomimicry study on him. Most interesting still the turtle shell study. The turtle shell can mimicked and developed into different kind of real life solutions. I was surprised that high potential mimicry and development of the shell turtle throughout the studies. It is the reason why blog development is interesting. 

Do you think that your design is patentable? Is it unique enough to be approved?

The design is pantentable. Turtle shell consider one of the most hardest biological structure among all the animal species. The mechanical properties of turtle shell can be mimicked to form new biological or non-biological material which can be well performed in withstand high physical impact or pressure driven such as body armor, automotive, aerospace and other fields. A harder but less denser material mimic from turtle shell may has a high market value and advancing technology to a new level. 

Did you think that working as a team made this project easier or harder? Why?

It is definitely good idea for the working work as a group. More manpower and different ideas came from different brains to make this blog more interesting. Especially thanks to Vincent Khaw that put a lot of effort in this blog management and proposing great idea. The most significant and valuable post is the I-beam modification which has a high social impact on modifying one of the most common products in market. 

Conclusion

First of all, thanks you all for following this blog throughout the 13 weeks journey.

Sad to say, we have finally come to an end of the project. Which mean, this is our last post :(

Throughout the  13 weeks journey, we have carried out critical thinking on mimicking the both mechanical and chemical properties of freshwater turtle based on literature review.

At the early stage, we study what is biomimicry and decide which animal to adopt as our study target. The searching for a suitable study target (or partner) come to an end when we found Turtle General, a red-eared slider which full of mystery.

Following by that, a long journey of scientific study and experiment was carried out on the red-eared slider. After a rigorous study on his habitat, behaviour, anatomy, and physiology, we have came out with an idea to mimic its shell structure to improve the steel beam mechanical structure. We found that the carapace (upper part of turtle shell) is in the form of complex structure (rigid-flexible-rigid) which results in higher cyclic loading tolerance that ensure the turtle shell is able to withstand frequent attack from the enemy. By mimicking the turtle shell into steel beam design, it allows the steel beam to withstand high amount of cyclic loading without fatigue. This improve the lifetime of steel beam and helps to improve the durability of building structure. This idea is cost efficient and require least amount of modification on the current manufacturing process, thus it is doable and will attract a lots of interest from experts working in construction industry. 

At last, we hope you guys have learned the basic knowledge on red-eared slider and give you a new insight on biomimicry technology. For people who is interest on the full details of this research, we welcome you to contact us by leaving a comment or email to us. 

Till then, see you guys !

Individual reflection - Jason Khoo Chang Jian

What was the most interesting proposed used of biomimicry that was developed in blog? Why?

The first thing that came across my mind was turtle can be proposed in biomimicry. The most general ones would be turtle shell. Why turtle shell? Because of its hard and rigid shell that is made up of keratin. From here, we analysed what turtle shells can be mimicked into. As this blog was being developed from time to time, I felt surprised because there are quite a number of things that can be mimicked from turtle shells than I expected!! Hence, making this blog interesting.

Do you think that your design is patentable? Is it unique enough to be approved?

This design is definitely patentable because the mechanical properties of the turtle shell can be used in many things such as bridges (stability) as well as body armour (protection). Since we know the behavior such as yield strength and Young’s modulus for the material, hence, the proposed design can be further studied. If it is financially feasible, it would definitely bring advantages to the community.

Did you think that working as a team made this project easier or harder? Why?

Working as a team is easier because we have more manpower whereby one will help in proposing ideas, doing research, compiling as well as simulation, thus, the workload will be much easier and save time. I would like to specially thank Khaw Wei Chuen for his effort on SolidWorks. The simulation that he conducted allows us and readers to have an in depth understanding on the analysis that we proposed from turtle’s shell. Without him, the blog might not be comprehensive.

Bio-inspiration - Turtle Shell used as Body Armour

Protective armours were found in nature a long time ago and they consist of several number of designs. However, these designs are rarely structurally rigid: nature often prefers multi-layer material systems providing maximum impact protection at a weight that has the possibility of exhibiting high fracture toughness and impact resistance. The materials for armours are usually from ceramics and polymer matrix composites whereby composite armour is made of a hard strike ceramic face made of tiles as well as fiber reinforced composite backing plate. The purpose of the front ceramic layer is to prevent the high pressure forces on the backing composite plate by projectile deformation whereas composite backing plate is utilized in absorbing its kinetic energy.

Armours can be mimicked from the turtle shells whereby the shells are covered by thin keratinous wavy multi-layers and termed scutes. These keratins are useful in such a way that the proteins from keratins are able to protect the epithelial cells from damage. Hence, these features serve as a defense mechanism whenever they are attacked by predators. Similarly, when these feature is applied in body armours as well as shields, it will be able to protect the soldiers from incoming attacks during combat. Here are 2 examples: Traditional and modern day body armour:

Figure 1. Traditional body armour worn by Roman soldiers. The shield is design according to the shape of turtle shell

Figure 2. Modern military body armour from Korea Military Force (KMF)

In the present day, the analysis of body armour evolution in turtles results in several design principles:

1.      Maximize size of body armour

2.      Create smooth surfaces

3.      Create multilayer body armour

4.      Introduce shock absorbing layers

5.      Minimize weight

6.      Maximize articulation

The Romans have imitated the function of the turtle shell with military maneuver in which soldiers marched in a rectangular formation apart from body armour:

1.      Head holding shields at the front

2.      Side holding shields at the side

3.      Soldiers in the middle holding shields over their heads

Figure 3. Soldiers in rectangular formation with their shield to cover from external impact

References

1. B. Achrai, B. Bar-On, and H.D. Wagner, “Biological armors under impact-effect of keratin coating,     and synthetic bio-inspired analogues,” Bioinsp. Biomim, vol. 10, 2015.

2. T Arciszewski, and J. Cornell, “Bio-inspiration: Learning Creative Design Principal ,” 

Individual reflection - Tee

Engineering and Biomimetic is a module that study about the conversion of natural to engineering application to solve some engineering problems. There are 3 main objectives in this subject which are to analyze the limitations and technologies for the adoption of nature in engineering design, evaluate the sustainability of biomimetic engineering system and mechanism of energy transfer within the living beings. To fulfill these 3 objectives, students are required to form a group (about 4-5 person per group) and write a blog about the experience for adoption of a living substance.

Our group choose to adopt a red-eared slider which is a very popular turtle pet. We choose to adopt this turtle is because it is easy to adopt, abundance, cheap and its living and habitats are quite interesting. Besides the adopting of pet, we also required to research about the anatomy and characteristic of the pet from literature. This is my first time to adopt a turtle type pet, therefore I have zero knowledge on the pet before we adopt it. When I first adopting the turtle, the main problem I have is the living environment of the pet. Since initially I thought turtle living environment is in water, I have pour in many water inside the container. However, based on my observation, I have found that turtle will take their head out of the water after a certain time to breathe, thus I have reduced the water level in the container to allow them breathe easily. Besides that, I have put a small rock which is used as a place that can help them escape from water for a while. The rock cannot be too big, because it may hit the turtle and cause some injuries on it. The second problem I have faced is the smelly odor that come out from the water in the container. To solve this problem, the water inside the container have to be changed daily. Aside from the adopting of turtle, the problem I have in writing blog is the arrangement of the blog article since I never wrote a blog before.

After the adopting of turtle, the main lesson I have learnt is that we have to put much care and love on the living substance we adopting. We have to take responsibilities on their living environment, foods, habitats and many more. Besides that, I have more understanding on the knowledges of the red-eared slider such as its anatomy, characteristics, habitats, its biomimicry theories and many more. I think this is a good assessment for students as it can help them to have more understanding on the objectives of the module which may be hard to fulfill just from the lectures. 

Individual Reflection - Vincent Khaw

What was the most interesting proposed used of biomimicry that was developed in blog? Why?

Throughout the 13 weeks journey, I learn a lots from the adopted turtle which include its behaviour and both mechanical and chemical structure of its body. The most interesting idea proposed used of biomimicry used from the turtle is using the rib-suture-rib complex structure to enhance the design of a I-beam. The zigzag pattern and collage-made suture make turtle shell to gain better resistance against cyclic loading without sacrificing its rigid properties. By adapting this design, it helps to extend the lifetime of I-beam and avoid unpredictable fatigue occur. 

Do you think that your design is patentable? Is it unique enough to be approved?

This design is never reported and consider a state-of-the-art technology that has wide range of application that cover construction, defence and weapon, automotive, aviation, etc. Therefore, I think this design is patentable and economic viable which able to advance the current technology to the next level. 

Did you think that working as a team made this project easier or harder? Why?

It is definitely better to work as a team instead of individual. As a project leader, I receive a lots of help from Jason Khoo who helps carried out survey and analyzed the information. Unfortunately, William Chia and Tee are unable to perform well in this project as their lack of time management skill make them absence most of the time. Self-discipline and responsibility are definitely the two main criteria to shape the personality of an engineer. I wish William Chia and Tee a good fortune and hope they can correct their misbehaving that i observed from this project. 

Novel Industrial Application - Reversed Engineering Worksheet

Do you think your product, building, or system would work if manufactured?

The modified I-beam has a similar cost with the commercial I-beam that gives better mechanical performance in terms of fatigue loading. Apart from that, it requires least modification to the current manufacturing process. Therefore, I think modified I-beam will work pretty well if manufactured and sell into the market. 

Do you think that you could raise funds to pay for manufacturing? How would you go about raising funds?

I think this ideal will attract a lot of interest from people working in the construction industry. I will prepare a proposal and submit to the respective company to ask for their collaboration on this project. Apart from that, I can also upload my work onto the fund raising website to ask for donation from the public or potential investor.  

Do you think that many engineers explore solutions from nature into their inventions?

I think many engineers adapt solution from the nature into their work nowadays. The solutions found from the nature is environmentally friendly and able to interlink with other system to form a ecosystem-alike working environment which helps to save cost and reduce shutdown frequency. 

Novel Industrial application - Modified I-beam

I-beam, also known as Universal Beam (UB), is a I-shaped beam that commonly used in the construction industry as support element. It is consists of a horizontal flange ("I" shape) and a vertical "web" element. The flange is design to resist bending momentum while the web is designed to resist shear forces. I-beam is commonly made of mild steel that behave follow the Beam theory. The I-beam design is evaluated in terms of its stiffness, yield stress, bending failure, and shear failure. The design of I-beam is governed by the ASTM standards (For example: ASTM A9992).   

In Figure 1, a computational simulation was carried out to evaluate the performance of commercial I-beam and modified I-beam. The two major evaluation criteria for the I-beam are governed by Von Mises Stress and displacement rate. Von Mises Stress determine the mechanical failure of a material by checking the yield stress of the material. The mechanical design is said to fail if the maximum Von Mises Stress induced on the material is higher than the yield strength of the material. The concept of Von Mises Stress is governed by distortion energy failure theory while failure occur when distortion energy in actual case is greater than distortion energy in simple tension case. In the simulation, the selected material is alloy steel with a Yong's Modulus of 2.1E11 N/m2 and Yield Strength of 6.2E8 N/m2. Refer to (a) and (b) from Figure 1, the maximum value of Von Mises Stress is fixed at the end of the center plate with a value of 2.2E8 N/m2 and 6.2E8 N/m2 for commercial and modified I-beam , respectively. Both design have maximum Von Mises Stress value lower than the yield point value of alloy steel, thus the design is consider safe. The simulation result is in agree with other literature which showed that rigid material has higher loading resistance than complex (rigid-flexible-rigid) material. From (c) and (d) from Figure 1, the maximum displacement rate for commercial and modified I-beam are 4.92E3 mm and 1.07E2 mm, respectively. The results showed that modified-I beam has greater flexibility which is able tolerate longer cyclic loading. 

Steel beam is widely used for bridges and industrial buildings. In the design of bridge, the shear studs are increase with a steadily rising number of high-cycle loading which lead to fatigue failure during the lifetime of the structure. By adapting the complex structure from turtle shell, it can increase the lifetime of steel beam which is able to improve its loading resistance and fatigue resistance from the steel beam structure.           

(a)

                                                                                (b)

(c)

(d)

Figure 1. The mechanical performance of normal and modified-I beam based on SimulationExpress. (a) and (b) showed the Von Mises Stress from commercial and modified I-beam, (c) and (d) showed the displacement rate from commercial and modified I-beam

References
1. "What is Von Mises Stress", Learnengineering.org, 2016. [Online]. Available: http://www.learnengineering.org/2012/12/what-is-von-mises-stress.html. [Accessed: 04- Jul- 2016].

Component of innovative I-beam

The modified I-beam has been shown in Figure 1. Refer to the figure, it shows that the modified I-beam is divided in to three parts with a circular rod at the center. The modified I-beam is mimicking the mechanical structure of carapace. The carapace arrange in the form of rib-suture-rib where rib is connected to the flexible suture sites. As you can see, the rigid alloy steel plate is separated by a silicon rubber rod at the center. Silicon rubber is chose as the major material to construct the rod to mimic the suture-alike structure with a similar flexibility and impact resistance in terms of this Yong's Modulus and Yield Strength. In addition, silicon also make the I-beam more resistant toward fatigue loading which expand the lifetime of the I-beam. This modified I-beam adapt the biological concept from turtle shell with a relatively low cost to manufacture. Further studies on the application of modified I-beam and the mechanical performance of I-beam can be found the the following posts.
Stay Tune !!!!!

Figure 1. 3-dimensional view of the modified wide-flange (W) shape I-beam. 

Figure 2. A actual view of commercial wide-flange (W) shape I-beam that designed according to ASTM standard 

Bio-inspiration - Turtle Shell used as Chinese Medicine

The turtle shell is commonly use in food and chinese medicine to cure certain disease or used as nutritional supplement. Below is a video that showed one of the dessert that made by turtle shell, Gui Ling Gao (also known as turtle's jelly)

Bio-Inspiration- Turtle's Shell used as Chinese Medicine

Turtle shell has been used as both food and medicine since ancient time in China and is recorded in the Shennong Bencao Jing, which is a medical handbook that being used by the ancient physician for centuries as a standard guideline for chinese medicine practice. According to the chinese medicine, turtle shell is often use in rehmannia-based formulas that nourish the Yin and calm the Yang. In modern study, it found that turtle shell does provide a significant hormone effect to human body which caused by the nutritional components (calcium and protein) contains inside the turtle shell.  

Figure 1. The cover page of Shennong Bencao Jing. It is a medicinal handbook that commonly used in the chinese medicine practice

The bottom part of the turtle shell, which is also known as plastron, is the desire part which has significant pharmacological value instead of the top part of the shell (also known as carapace). Although study showed that there are twice the amount of gelatin (desired bioactive compound) as the plastron from the carapace, but the consumption of plastron is still higher than carapace for chinese medicine. The plastron is separated from the animal carcass and cook in 20% lime water in high temperature and the water is consumed by the patient. In addition, vinegar processing is consider another well known method that able to boil the collagen from plastron into gelatin.

Figure 2. Chemical structure of gelatin

The major chemical constituents of turtle shell (plastron and carapace) are calcium, collagen, gelatin, and a trace amount of fats, magnesium, zinc, vitamin D. The calcium compound make up the major part of the shell and  is able to cure calcium deficiency-related disease such as bone disease ricket, which is caused by impaired deposition of bone calcium. According to a case study, it was reported that calcium provided by the turtle shell has similar effect as the calcium supplement such as cod liver oil and calciferol. Moreover, the gelatin (make up 7% of the plastron) converted from collagen in boiled water is develop to inhibit arthritis, angiogenesis. In addition, the gelatin polypeptides (fragments that produced from digestion) is able to treat bleeding as well. Moreover, a turtle shell-based formula that combined with methimazole to treat Grave's disease showed that 14 out of 25 patients had complete remission of symptoms at the end of the treatment. The raw turtle shell is also reported to traditional use for treating vertigo, tinnitus, deafness, headache, and convulsion.     

Figure 3. Actual view of plastron of a turtle

References

1. S. Dorr, "Tortoise Shell: with Brief Reports on Treating Aplastic Anemia and Parkinson's Disease", Itmonline.org, 2016. [Online]. Available: http://www.itmonline.org/arts/tortois2.htm. [Accessed: 04- Jul- 2016].

   

Bio-inspiration from Turtle's Shell - Skiboard

Skiing is a type of recreational activity where participants use skis to glide on snow. The ideal ski (also known as skiboard) can withstand high levels of pressure in turns and also able to maneuver. These two features usually require two different types of skis:

1.       Expert skiers that preferred rigid skis

                                 2.       Intermediate-level skiers that preferred flexible ones

But a new type of ski is able to combine the two different features of the skis into a design based on the turtle scales. This design allows the skis to be able to maneuver while entering and exiting turns, at the same time stiffen up in the middle of several turns to improve the skis’ grip on the snow. The turtle shell design was a joint effort based on a research institution from École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, Institute for Snow and Avalanche Research (SLF) and a Swiss ski manufacturer.

Figure 1. Turtle's shell structure and cycling-loading analysis trend result

The idea of mimicking the morphology of turtles was introduced by Véronique Michaud, a researcher at EPFL. She stated, “The scales of a turtle interlock, like a jigsaw puzzle, and they are connected by a polymer. When turtles breathe, the scales separate slightly and the shell becomes flexible. But when an external shock occurs, the shell tightens and stiffens”. 

The new ski design was conducted by embedding aluminum plates with a snake like shape fissure into precise locations at both ends of the skis. When the skis bend in one turn, the plates at both sides of the gap come together and the ski stiffens, allowing the skier to achieve stable and precise turns. As the skier comes out from one turn, the gap reopens allowing the ski to be more flexible again and easy to handle. Hence, the alminum plates function like scales and a special type of rubber between the plates is similar to the polymer exist in the turtle shell. The ski design was shown as follows:

Figure 2. The mimicking of turtle's shell structure on skiboard. 

The newly designed ski was proven by Olympic ski champion, Tina Maze as she attempts to utilize the new design for a ride. She stated, “As the pressure on the skis gradually increases during turning, the skis really gripped the snow and were stable. I was impressed by the ease with the plates coming together and separate.”

The new design also improves the safety during the turn which prevents skiers from falling down causing severe injuries, and worst case, it could cause fatality since skiing is hurtling down with steep slopes.

References

1. L. Pessina, "Ski design inspired by turtle scales", MEDIACOM, 2015. [Online]. Available: https://actu.epfl.ch/news/ski-design-inspired-by-turtle-scales/. [Accessed: 03- Jul- 2016].

The Evolution of Turtle's Shell

The Evolution of Turtle's Shell

The video below shows the evolution of turtle's shell from the ancient to the modern era to adapt new environment and external trauma.

Mechanical Performance of Turtle's Shell

Mechanical Performance of Turtle’s Shell

Biological composite shields have been increasingly investigated in recent years. In turtle shell, there is a unique arrangement of alternating rigid rib and flexible suture elements that give rise to superior mechanical performance. The rigid structure of turtle shell protect the internal organ from external damage while some degree of flexibility allow the respiration and locomotion. The top dorsal of the turtle shell (namely carapace) was reported in the scientific literature and it found that carapace contains unique macroscopic configuration of complex alternating strips of rigid boney ribs. The carapace is consists of both alternating rigid (rib) and flexible (suture) elements in an arrangement of zigzag tips of rib connects to the flexible suture sites. The image of turtle shell has been shown in Figure 1. 

Figure 1. Ventral view (inside-out) of turtle shell. The red arrow mark the individual suture adjoining to rib

Flexural high stress cyclic loads were applied to both rib, suture, and complex specimens obtained from the carapace.  Static bending test were tested for specimens cut from the carapace to measure the strength for each specimen. The average strength for different part of the turtle shell has been shown in Table 1.

Table 1. Average strength for different part of turtle shell measured by quasi-static bending stress

Type of specimen	Strength (MPa)
Suture	51.3
Complex (Whole shell)	71.2
Rib	121.6

Based on the results, it showed that the rib is the strongest as compared to suture and the complex structure of turtle shell. The ribs demonstrate better fatigue resistance than sutures due to layered sandwich micro-structure (two perpendicular parallel-fibered sub-layers). However, the complex specimen made of a sequence of rib-suture-rib-suture-rib elements are able to withstand repeated loads due to its fast unlocking mechanism.

            According to the CT scan, it showed a decreasing mineral concentration from the shell toward the suture. The un-mineralized suture integrate with the rib allow extra degree of flexibility underload. This interdigitating nature of the structure of the sutures allows them to move freely towards each other under small load. However, the shell becomes rigid when adjoining dermal bones meets under critical deformation threshold. The concept of the nature of the shell structure is depicted in Figure 2. The SEM images of the complex 3-dimensional structure of suture joining the rib of the turtle shell have been shown in Figure 3a, b, c.   

Figure 2. Schematic depiction of unloaded and loaded deformed beam. The parameter D, W, and α are denote as pitch of the zigzag, gap of the suture, and maximal bending angle. 

Figure 3. SEM images complex 3-dimensional structure of suture joining rib. (a) at the interdigitating suture, (b) at the cancellous region adjacent to suture. The thin dorsal cortex region shown below the dashed green line is gradually thicken away from the center from suture to rib , (c) Higher magnification of (b). The red elipse marks the fracture region.

References

1. B. Achrai and H. Daniel Wagner, "The red-eared slider turtle carapace under fatigue loading: The effect of rib–suture arrangement", Materials Science and Engineering: C, vol. 53, pp. 128-133, 2015.

2. R. Shahar, S. Kraus, E. Monsonego-Ornan and P. Fratzl, "Mechanical Function of a Complex Three-dimensional Suture Joining the Bony Elements in the Shell of the Red-eared Slider Turtle", MRS Proc., vol. 1187, 2009.

General Introduction of Red Eared Slider

Background

Red-eared slider (scientific name: Trachemys scripta elegans), which is also known as red-eraed terrapin, is one of the most distributed turtle in the world. It is a subspecies of pond slider and belonging to family Emydidae. It is the most popular pet turtle in United Stated and also popular in rest of the world. Its originally came from Southern United States and Nothern Mexico, and now has available in many other places due to the pet release. Figure 1 shows the red-eared slider our group adapted. 

Figure 1: Red Eared Slider adpated by us

General Description

The turtle is a freshwater semi-aquatic turtle with a fairly flat, oval shell and a weakly keeled carapace. Soft waters with muddy bottoms, aquatic vegetation and suitable sites for basking are their prefer habitats. Their colors are range from bright greens and yellow to more muted olives, brown, and some even blacks. Small red stripe can be seen around their ears and this has become the origin of their name. The average length ranges of this species is around 15 to 20 cm (6 to 8 inch) and the longest length it can reach is 40 cm (16 inch). The female species is often larger than male. On the other hand, their lifetime is fall between 20 to 50 years and it has greatly influenced by their living environment.

Sexual Dimorphism

There is some dimorphism between male and females of this species. It is difficult to identify the sex of young red-eared slider because their looks similar. However, the sex of its adults are easier to differentiate as the shells of males are smaller than of females. Male species reached sex maturity when their carapaces reach 90 to 110 mm and females reach maturity when their carapaces reach 160 mm to 200 mm. Besides that, the claws of males are longer than females, which makes them easier to hold on to female for mating. The male tails is usually thicker and longer. Figure 2 has clearly illustrated the differences between male and female species. 

Figure 2: Male and Female Red-Eared Slider

Habitat and Behaviour

The red-eared slider is very adaptable to the environment, even has the ability to hibernate in the winter. It can inhabit in a source of stagnant, warm water, for example lakes, ponds, swamps, creeks, streams or rivers. They can tolerate brackish water, thus they also can be found in coastal waterways. They stay in calm water area where there are some rocks or tree trunks for them to climb on it and rest in the sun. On the other hand, they eat everything, from fish, frogs, insects, vegetation to ducks. Figure 3 shows that the turtles are sun-bathing on the root. 

Figure 3: The turtles are sun-bathing on root

Threats and Control

Due to pet released and their high adaptable ability, their population has been increase in several areas. This turtles are aggressive and bold, and they will compete for foods and habitats with native turtle species. Besides that, they may interbreeding with other similar species and diluted their gene pool. They also can carry some unusual pathogens to their new environment, which will have some great damage apart from turtle themselves. In order to control these turtles, hunting, trapping and collecting eggs is encouraged in some areas. However, these methods have caused overhunting and decline of the species. A better solution in urban areas would be capture-sterilization-release, which would take a long time to work and be an ongoing one. 


References

1. J. Burger, “Red-eared slider turtles ( Trachemys scripta elegans ),” no. December, 2009.
2. www.bcreptiles.com, “Red-eared Slider Scientific name : Trachemys scripta,” pp. 3–5. [online] Available at: http://www.bcreptiles.ca/docs/76E182A811776B7B.pdf [Accessed: 30 April 2016]

Turtle's Anatomy - Shell

Figure 1: Shell of a red-eared slider turtle

The shell which can be seen in Figure 1 consists of bony plates that are mostly covered with shields called scutes (osteodem). The shields are entirely made of keratin. The shell of the turtle is divided into 2 sections:

• Upper or dorsal carapace
• Lower, ventral carapace or plastron

These are similar to scales and they are derived from the red-eared slider’s epidermis. However, the top layers of the scute will fall off when the red-eared slider begins to shed. A bridge connects the carapace and the plastron.

The carapace (top shell) is nicely rounded and smooth. The carapace has a black and yellow pattern. Hatchlings start with a bright green carapace that is slightly soft whereas adult red-eared sliders have a darker green carapace. As the red-eared sliders age, the colour of the carapace will grow darker and the patterns will be less visible. Hence, this is one way to determine the age of the red-eared slider. The carapace of a red-eared slider can be seen in Figure 2.

Figure 2: Carapace, upper section of the shell

The plastron is similar to the carapace. it is also smooth but it is usually yellow in colour with a distinct and unique pattern that can be seen in Figure 3.

Figure 3: Plastron, lower section of the shell

Let’s go in depth on the carapace and the plastron. Both section of the shells have their own specific name at all corners of the shell which can be seen in Figure 4.

Figure 4: Illustrative structure of carapace and plastron scutes respectively

Carapace Scutes

• Vertebral scutes cover the spinal region of the turtle.
• Pleural scutes cover the ribs of the turtle.
• Marginal scutes are located at the outermost scutes of the turtle.
• Supramarginal scutes fall between the marginal and pleural scutes.
• Cervical scutes cover the neck region of the turtle.

Plastron Scutes

• Intergular scutes cover the throat of the turtle and the anal scutes.
• Gular scutes are the first lateral scutes followed by the humeral scutes.
• Pectoral scutes are laterally paired near to the pectoral girdle of the turtle.
• Abdominal scutes cover the abdomen of the turtle.
• Femoral scutes cover the femur of the turtle.

Reference

1. Newman, S. (2016). Red-Eared Slider Turtle Facts, Habitat, Diet, Pet Care, Pictures. [online] Animalspot.net. Available at: http://www.animalspot.net/red-eared-slider-turtle.html [Accessed 23 Apr. 2016].
2. Virginiaherpetologicalsociety.com. (2016). Red-eared Slider. [online] Available at: http://www.virginiaherpetologicalsociety.com/reptiles/turtles/red-eared-slider/red-eared_slider.php [Accessed 23 Apr. 2016].