Background: In the Biology class I took this year, we have to write a formal lab report every quarter. Formal Lab Reports usually take about 4-6 hours to complete not including time taken to perform the experiment. For the last quarter of the school year, we had to do a lot of dissections. The formal lab report for this quarter was on the frog I dissected. Take note, this lab report does not have anything gory about it but if you found dissecting animals in high school (if you are past high school) or if you think it is just gross then possibly read with caution. I hope you enjoy learning all about frogs!
Title: Frog Internal and External Anatomy Dissection
Name: Karibella Whitmore
Date: 5/7/2024
Purpose: To locate and understand a common grass frog’s external features and internal organs.
Background:
Frogs are some of the most interesting amphibians in the world. They breathe through their skin and can hibernate in cold weather! Frogs play an important part in their ecosystems. They are good food for fish, birds, and snakes, and they also help control bug populations by eating bugs.
The frog specimen that was dissected was from Kingdom Animalia, Phylum Chordata, Class Amphibia, Order Anura, Family Ranidaem, Genus Rana, and Species Forreri.
Rana Forreri was discovered by Edward Drinker Cope. Cope was a famous paleontologist who also spent a lot of time studying reptiles and amphibians and tagging new species. William H. Forrer, a naturalist and collector, provided most of the information for Cope to name Rana Forreri. Rana Forreri is named after William H. Forrer. Forrer collaborated with many famous scientists, providing them with specimens for their taxonomy work.
Karen Lips is a professor of Biology at the University of Maryland. She greatly contributed to the discovery of chytrid fungus, which uses frog skin to reproduce. Many years ago, she lived in a jungle and studied the growth and reproduction of frogs. She returned to the States to publish her findings but had to go back to the jungle for one more experiment. When she returned to the jungle, all the frogs had disappeared. She went to a different location in Panama to study more frogs, and while she was there, all the frogs began to get sick and die. She sent some off to a lab, and a skin infection was found but was not identified. The New York Times published a photo of the infection, and people in Australia and people from the Washington DC Zoo helped identify it as a fungus. More research was conducted, and it was found to be Chytrid Fungus. Karen Lips helped identify this fungus that is killing off frogs around the world.
Another scientist who has been studying sick frogs is Tyrone Hayes. Hayes majored in Biology at Harvard and was hired to study the effects of the herbicide Atrazine on frogs. His research found that atrazine inhibited the growth of the larynx in male frogs. More research found that the male frogs exposed to the atrazine developed female gonads and eggs and were able to fertilize them. The male frogs still had male gonads but were unable to fertilize eggs. His discoveries have led to much controversy about atrazine and its effects on wildlife, ecosystems, and even humans.
Experimental Procedure:
I. Materials:
- Dissection Tray
- Dissection Scissors
- Forceps
- Scalpal
- Two Dissection Probes
- Plastic Exam Gloves
- Dissection Pins
- Frog Specimen
- Face Mask (optional)
- Eye Glasses (optional)
II. Safety Precautions:
Be careful when cutting with scissors and scalpel. Use precaution when moving pins. Do not inhale or eat frog specimens. Sharp tools should be kept away from children.
III. Procedure:
- Make an incision with the dissection scissors starting at the anus on the ventral side and continuing to the area just below the shoulders.
- Make two identical incisions or the anterior side of the original incision running right to left. Repeat on the posterior end of the original incision. You should be able to pull back flaps of skin to see the internal organs. If needed, gently cut away tissue holding the skin to the organs with a scalpel.
- If your frog is female, remove all the eggs to expose the internal organs. The eggs are small black-and-white dots.
- Examine the internal organs and attempt to locate the heart, stomach, lungs, intestines, gonads, and other major organs.
- Using the scissors, make an incision in the side of the stomach to see what the frog’s last meal was. Frogs eat their food whole so you might be able to identify what is inside the stomach.
- To see the muscle in the frog’s leg, carefully make an incision starting near the anus and the original incision. Gently cut only the skin and pull open the incision to see the muscles.
- Once you are finished examining the frog, dispose of all organs and frog parts in a safe plastic bag.
- Wash dissection tools and put them away for your next dissection.
Data/Results:
Data: (Must include 2 hand-drawn labeled diagrams of the specimen: one external feature, one internal organ)
Discussion: Explain the functions of features and organs you observed in the specimen.
This experiment aimed to identify and find a frog’s internal organs and observe and identify the external features. Inside the frog specimen, the heart, veins, arteries, intestine, stomach, gonads, eggs, muscles, and lungs were all observed. The frog heart has three chambers and is used to circulate blood around the body. It is connected to the rest of the body by veins arteries, and capillaries. The frog has a closed circulatory system.
The lungs are part of the respiratory system and help the frog breathe. The skin and mouth also aid in the oxygenation of the frog’s blood. The frog uses its skin to breathe during hibernation because it usually hibernates in mud.
The intestine and stomach are part of the digestive system. The stomach digests food and stores it, and the intestine further digests the food and secretes any waste through the anus.
The gonads are part of the reproductive system and were female in this frog. The eggs are undeveloped baby frogs that were not yet fertilized. The muscles help the frog to move in various ways, whether jumping or swimming. All these organs help the frog to live well and thrive.
Conclusion: Summarize the key things you learned about your specimen.
This experiment aimed to learn more about and identify the internal organs and external features of a frog. The most important things learned from this dissection were the internal anatomy of the frog, its role in the world, and that frogs eat their food whole, which provided a very interesting surprise for those dissecting. Most of the internal organs were found and recorded, and all of the external features were found. The student learned the importance of precision and carefulness while dissecting. The student also learned that female frogs usually have very many eggs. This dissection was a challenging and fun activity for a biology student and will hopefully be repeated by many biology students in the future!
Photo/Video: Include a photo of you with your specimen.
References:
Flynt, Sean. “Biologist Warns of Health Effects of Common Herbicide.” Samford University, 11 Apr. 2018, www.samford.edu/news/2018/04/Biologist-Warns-of-Health-Effects-of-Common-Herbicide.
“Lithobates Forreri (Boulenger, 1883) | Amphibian Species of the World.” Amphibiansoftheworld.amnh.org, 10 May 2024, amphibiansoftheworld.amnh.org/Amphibia/Anura/Ranidae/Lithobates/Lithobates-forreri. Accessed 10 May 2024.
Schlecht, Volker, et al. “Video: Opinion | the Waiting.” The New York Times, 12 Dec. 2023, www.nytimes.com/video/opinion/100000009184500/the-waiting.html. Accessed 10 May 2024.
—. “Video: Opinion | the Waiting.” The New York Times, 12 Dec. 2023, www.nytimes.com/video/opinion/100000009184500/the-waiting.html. Accessed 10 May 2024.
Robinson, Roosevelt. “Nature’s Frogs.” Alabama Cooperative Extension System, 10 Apr. 2023,
www.aces.edu/blog/topics/urban-extension/natures-frogs/#:~:text=Frogs%20are%20an%20integral%20part.
Formal Dissection Report Checklist
Check off each item under each category to verify you’ve included the information.
Background
Topic SentenceIntroduced and explained the classification of your specimen.Researched three scientists who have contributed to our understanding of the specimen.Who discovered it and how did they learn about how the specimen fits into the ecosystem?Which scientists throughout history have added or changed our understanding of the specimen, experiments they performed and their conclusions.Which scientist(s) used the specimen to further our understanding in various fields (medicine, space, sports, etc.) today and how are they applying it?
No personal pronouns.Used complete sentences and correct grammar.Used paragraph format.
Experimental Procedures
Listed materials (not in sentences)Listed safety precautions (if any)Listed ProceduresUsed my own wordsWrote steps as a numbered list, not a paragraph.Clearly written so can be duplicated.
Data/Results
I included a labeled hand drawn diagram of the external features of the organism.I included a labeled hand drawn diagram of the internal organs of the organism.My labeled diagrams are clearly labeled and easy to read.My labels are horizontal and straight.
Discussion
Restated purpose.Discussed the purpose and functions of the external features observed.Discussed the purpose and functions of the organs observed.Discussed how the organs are connected within a system.Discussed how the systems are connected to each other.
Conclusion
Restated purpose in one sentence.Summarized the key points/lessons learned about the specimen from doing this dissection.Included how the specimen fits into its ecosystem.
Photo
Included a photo with me included in the picture.
References
Used the correct format to list sources, APA, or MLA format.Avoided summary sources (Textbooks, encyclopedias, Wikipedia, how stuff works, khan academy, etc.)Used websites that present detailed information, like college sites, research sites, sites dedicated to the topic.
