Sample Laboratory Report on Biology: Frog Dissection Experiment

Frog dissection is a common biology activity that helps introduce students to basic anatomy. This experiment can teach students how to use certain laboratory tools and gain a better understanding of how body parts work. This sample biology lab report will contain the basic parts of a high school science report and can act as a guide for students who are writing a similar paper.

Title: Observing The Similarity Between Human and Frog Anatomy

Introduction

Frogs belong to the category “amphibians” which are small vertebrates that require both a terrestrial and aquatic environment to survive. They begin as eggs, then develop into tadpoles, and eventually become adult frogs. Their growth processes are different from reptiles and mammals, however, these animals share some common characteristics with humans. They possess external and internal body parts that are also present in humans. This makes frogs a subject for scientific study since they can provide insights into human anatomy without the need to dissect or study human bodies.

Frogs and humans have similar circulatory, digestive, respiratory, and nervous systems. They utilize most of their body parts the same way except for species-specific characteristics, such as frogs’ ability to breathe through their skin and humans’ capacity to use delicate tools with their fingers. These characteristics are the result of evolution which will be distinct, especially for different animal groups. Despite this, frogs and humans evolved with many anatomical similarities. Additionally, the Department of Energy’s Joint Genome Institute in Walnut Creek, California conducted a study that revealed that African clawed frogs possess at least 1,700 disease-related genes that are similar to humans. Experts can utilize this knowledge to learn more about human diseases, such as cancer and heart disease (cited in Moskowitz, 2010). Studying both the external and internal anatomy of frogs can further provide a better understanding of human anatomy.

Objective

There are many similarities between human and frog anatomy. This laboratory activity will help in understanding the anatomy of frogs and how the different parts are similar to humans. In this activity, the students will identify the external and internal parts of the frog, establish the functions of the parts, and observe the similarity between frog and human anatomy.

Materials

• One live frog (high school level biology classes utilizes already prepared frogs for this experiment)

• Any type of alcohol

• Cotton

• Surgical gloves

• Electric needle

• Large Paper

• Marker

• Dissecting Tray

• Dissecting kit - This kit will include the scalpel, forceps, probe, dissecting scissors, and pins

• Trash bags and a Ziploc bag

• Disinfectant soap

Procedure

Step 1.  First, the students prepared the materials for the experiment. The students placed the dissecting tray, dissecting kit, and marker on the table. The student then set the large piece of paper under the dissecting tray to cover the table and avoid unnecessary mess. They took out the scalpel, forceps, probe, scissors, and pins from the kit and placed them around the dissecting tray.

Step 2. Once all the tools were ready, the students took out the subject frog while wearing surgical gloves. The students took this time to observe and investigate the external part of the frogs. They first looked at the head of the frog, then the body, the limbs, the underside, the top side, and lastly, the rear. They took note of color, texture, and other distinctive external characteristics.

Step 3. After investigating the external anatomy of the frog, the students prepared for the dissection. They first needed to “pith’ the frog. “Pithing” means destroying the frog’s brain to paralyze it and prevent it from feeling pain during the dissection. To do this, the students used an electric needle. They aimed the electric needle on the head of the frog, adjacent to the brain. The location of the brain is somewhere in the middle of the head, between the ears of the frog. Note: If students find that their frog is too aggressive or active to handle, they can use cotton with alcohol to weaken the frog. Simply place the cotton over the frog’s nose and wait until it starts to calm or slow down. Once the frog has calmed down, the student can proceed with the “pithing”.

Step 4. The students then secured the frog on the dissecting tray and prepared it for cutting the skin. The students placed the frog on the tray with its belly facing upward. They then used the dissecting pins to secure the frog’s limbs on the tray. The students then used the marker to draw lines to guide them during the cutting procedure. They drew a vertical line from the tip of the mouth to the point where the two hind legs meet and two horizontal lines; one between the front legs, right under the mouth, and one across the area between the hind legs, perpendicular to the end of the vertical line.

Step 5. After the marking, the students began cutting the skin of the frog. The students used the dissecting scissors to cut from the point where the hind legs meet and moved on upwards towards the base of the mouth, following the marking lines. They used forceps to lift the skin and avoid damaging other parts. After cutting the necessary parts, the students used dissecting pins to secure the frog’s skin to the dissecting tray and prevent it from covering or touching the internal parts.

Step 6. Once the students have secured all the cut skin on the dissecting tray, they proceeded in cutting the muscles and bones. The students followed the same incisions that they did to the skin. They started cutting vertically from the area between the hind legs and then moved to the horizontal cuts. When cutting around the chest, the students had to cut the chest bones. Similar to the previous step, they used forceps to secure the muscles to avoid damaging other parts. They then used the dissection pins to secure the muscles to the dissecting tray. Note: The students had to pin the muscles overlapping the skin since the length of the muscles was shorter.

Step 7. The students then begin observing and investigating the internal organs of the frog and how they are similar to human anatomy. They used the scalpel to move the organs around and better view other parts. They took notes of the location of each organ and proceeded with removing each organ to get a better view of the anatomy. They placed the removed organ on the dissecting tray, keeping in mind their names and function.

Step 8. After the investigation process, the students cleaned up the area and disposed of the body and organs properly. They placed the frog and the removed organs in the trash bag. They secured the trash bag in a Ziploc bag and threw it along with the dissection tray and surgical gloves. For the dissection tools, the students used a disinfectant soap to wash them.

Results and Discussion

The students observed that many of the internal and external body parts of the frog are similar to humans. They observed that the skin of the frog is moist with tiny bumps. The frog had four limbs with webbed feet; two hind legs and two front legs. The webbed feet of the frog help the animal swim and navigate aquatic environments. The head of the frog is large, about more than half the size of its body. On the frog’s head are its protruding eyes, nostrils, and tympanic membrane. Inside the frog’s mouth were common parts like the tongue, internal naters (nostrils), set of teeth on the upper jaw, and glottis. For the internal body parts, the frog’s body contained the heart, lungs, liver, stomach, gallbladder, pancreas, spleen, and intestines.

The students observed that the limbs of the frog have different sizes. The hind legs are much larger than the front legs. This characteristic is similar to the human body where the legs are larger than the arms. For the frogs, the hind legs are larger since they use them for jumping and moving forward. The other external body parts of the frog also share similarities with human anatomy. Both frog and human heads contain the eyes, nostrils, and mouth. 

One of the differences is that humans have ears while frogs have tympanic membranes. These membranes are circular and can help in determining the frog’s gender. The students used the tympanic membranes and the frog’s forelimb finger to determine that the subject frog was a male. The frog’s tympanic membrane was larger than its eyes and the forelimb finger had an enlarged pad, all indicators of a male frog. The frog also only had teeth on its upper jaw, unlike humans that have teeth on both the upper and lower jaw. Despite these differences, both humans and frogs have well-developed senses of hearing, sight, and smell (Farley, 2018). Indicating that the body parts function similarly and are effective in providing basic senses to the species. 

The skin of frogs and humans is one of the main differences between the two species. As mentioned earlier, the subject frog had moist skin. This skin allows oxygen to pass through and directly go to the frog’s blood (Anatomy of the Frog, n.d.). This means that frogs can breathe through the mouth and through their skin, which humans cannot do. This characteristic is common in amphibians and is absent in mammals since the latter rely on their mouth and nose for breathing.

For the internal body parts of the frog, the students observe that they look very similar to human parts, aside from the small size. The frog’s liver is a large brown organ that covers most of the chest area. Above the liver is the frog’s three-chambered heart, which had two atria and only one ventricle. This is different from the four-chambered human heart which has two atria and two ventricles. Removing the liver from the body exposes the gallbladder, stomach, and intestine. To reveal other organs like the lungs, pancreas, kidney, and spleen, the students had to remove the newly exposed organs. From observation, the locations of the frog’s internal organs are slightly different from humans. Despite this, the functions of the organs are the same.

Conclusion

The frog’s external and internal anatomy looks and functions similarly to the human body. Frog and human eyes, nose, ears, and mouth are responsible for hearing, smelling, tasting, and seeing. Frog and human limbs function similarly with the hind legs growing larger than the front limbs or the arms. The frog’s circulatory, digestive, respiratory, and nervous systems function similarly to their human counterparts. However, there are also key differences and characteristics between humans and frogs. Frogs can breathe through their skin, have three-chambered hearts, webbed feet, tympanic membranes, and a much larger liver-to-lung ratio; all of which are absent in human anatomy. This frog dissection activity provided first-hand insights into the similarities and differences between human and frog anatomy which is helpful in understanding the functions of organs.

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Reference List

Farley, A. (2018). Similarities of Frogs & Humans [Online]. Sciencing. Available at https://sciencing.com/similarities-frogs-humans-8531808.html. Accessed May 25, 2022

Britannica Kids. (n.d.). Anatomy of the Frog. Britannica Kids. Available at https://kids.britannica.com/students/article/Anatomy-of-the-frog/274440. Accessed May 25, 2022.

Moskowitz, C. (2010). Frogs Surprisingly Like Humans, Genetically Speaking. Live Science. Available at https://www.livescience.com/6379-frogs-surprisingly-humans-genetically-speaking.html . Accessed May 25, 2022.