How To Dissect a Frog

In biology, dissecting a frog is an important experience.If you know how to do it right, you can have a profound learning experience.

Step 1: Get your frog from the dissection tray.

Frogs and other small animals are often used in biology labs to learn.Your teacher should give you all the necessary tools for the dissection of a frog.It doesn’t take a lot.You will need a clean dissection tray and some pins to hold the frog’s skin out.The rubber lining on the bottom of the tray is similar to a baking pan.You’ll need a scalpel, a pair of tweezers, dissection pins, lab instructions, and a frog to make an opening.Advanced science students used to be required to put down their frog themselves.The practice of fresh frog dissection is rare nowadays.Most of the time, you’ll get frog that have been dead for a long time.

Step 2: There are additional materials provided by the instructor.

A basic identification procedure is required for most frog dissection labels.You will need to open the frog, identify the basic organs and systems, explore the animal’s body, and fill out a lab report to complete the project.You should always defer to your instructor.If you don’t like dissection in class, tell your teacher.Digital alternatives are very common.

Step 3: Wear safety gear.

It’s important to wear latex or rubber gloves, safety glasses, and lab coats.It’s important to keep your hands, eyes, and mouth free of the formaldehyde used to preserve the frog for dissection, even though the specimen is sterile and safe.Wear the protective materials provided to you in the lab, and wash your hands after work.

Step 4: The frog should be on the back of the dissection tray.

Place the frog on its back in the tray to start the lab.If you want the frog to sit comfortably on its back, you may need to massage them out a bit, bending the legs and making the joints softer.

Step 5: The sex of the frog is known.

The easiest way to tell the difference between males and females is to look at their feet.The front feet of the male frog should have a bigger thumb pad than the female’s.If the specimen is female, keep an eye out for eggs and enlarged ovaries, which may need to be removed before you can identify certain organs.

Step 6: Take a look at the head.

Most labs want you to recognize a few important features on the head of the frog.The eyes are the most important and easiest to find on the frog’s head.You need to locate and label the mouth.The frog’s nostrils are used for breathing and should be far forward above the mouth opening.The round spot behind the eyes is where the tympanum is located.

Step 7: Take a look at the inside of the mouth.

If you want to examine the inside of the frog’s mouth, use your scalpel to cut the membrane that connects the hinges.You should be able to see and label the glottis, which connects to the lungs.The tongue is large and stretchy, making it easy to identify.The eustachian tubes are located to the left and right of the throat.The teeth behind the maxillary teeth are used to secure prey and keep it out of the mouth.

Step 8: The cloaca can be found.

Between the frog’s hind legs is where the cloaca should be.If necessary, use scissors to remove the abdominal muscles from the cloaca.It’s important to wait for instructions in the lab.

Step 9: The instructions are to open the frog.

For most of the time, you’ll start with a basic “X” pattern: one cut down each leg, connected by a single cut up the belly.To start, cut out toward each leg, then connect them with a single straight cut up the “girdle” in the center of the frog’s belly.It is common to open the torso with an “H” pattern.To do this, connect the arms and legs with a cut up the belly.If you need to open the frog, you can pull back the flaps and pin them to the tray.

Step 10: Pin back the flaps of the wall.

To get the skin out of the way and open up the frog, it’s usually a good idea to put it into the dissection tray with pins.Pull it back gently until it connects with the bottom of the tray, then use a pin at each corner to secure the skin back.Don’t tear the skin.

Step 11: The peritoneum is removed.

If you want to see the organs inside, you’ll have to carefully pick off the spiderweb-like covering of many of them.Carefully pierce it, be careful not to poke any of the organs, then remove it from the body and expose it.

Step 12: Find the fat bodies.

These should look like spaghetti with orange and yellow tubes on the abdominal wall.If you have a larger frog, the fat bodies may need to be removed.If you can’t see beyond this stuff, make sure it’s okay with your teacher to remove it.

Step 13: Find the bile duct.

The biggest organ in the frog’s body is the liver.It’s usually made of three big structures.It can also be streaked with a bluish or greenish color.Most of the time, you won’t want to remove the organs until you’ve identified them.They can help you find other organs in relation to what you have already identified.When the time comes, remove the instructions from your lab instructor.

Step 14: Pick out the heart.

The heart has a triangular shape.A single ventricle runs along the bottom of the frog’s heart.The conus arteriosus is the big vessel that comes out of the heart and pumps blood throughout the frog’s body.

Step 15: The lungs are under the heart and liver.

The frog’s lungs are small and shaped like little beans.You may have to pull the heart out of the way to find them.You’re not alone if you have trouble finding lungs.If you’re having a hard time, ask your teacher for help.

Step 16: Take a look at the gallbladder.

The bile from the frog’s stomach should be stored in a sac under the lobes of the liver.It looks a lot like snot.

Step 17: The stomach can be found by following the esophagus.

The frog has a tube in his mouth that leads to his stomach.Open the frog’s mouth and poke your probe into it to see where it leads.The next step in the dissection process is to find the stomach of the frog.

Step 18: The stomach can be found with the removal of the liver and intestines.

If you haven’t already, it’s usually a good idea to remove the liver at this point.The stomach has curves.Follow the curve of the stomach down to the bottom to find the pyloric sphincter, a valve that channels food into the small intestine.

Step 19: Take a look at the small intestine.

The duodenum and the ileum are connected by the mesentery and attach to the end of the stomach.The blood vessels that trail away from the mesentery carry the energy from food to the blood stream.The frog gets its strength and energy from the food it eats.Follow the small gut to the large gut.The cloaca should widen at the bottom of the small intestine.The waste leaves the body of the frog.

Step 20: You can find the spleen.

The frog’s spleen should be shaped like a little orb.The energy from the frog is carried away by the blood held during the digestion process.

Step 21: Carefully open up the stomach.

Instructors may or may not want you to open the stomach.Follow instructions.To open the stomach with a small horizontal cut, use your scalpel.If spitting occurs, keep your face up and away.What appears to be inside?You might see bile or some partially eaten food.

Step 22: There is a way to find the kidneys.

The excretory and genital systems are connected in the frog.The flat bean-shaped organs that make up the kidneys can be found in the lower back near the spine of the frog.They should be dark and highlighted by yellow fat bodies, which are attached at the top.At this point in the process, you probably won’t remove any organs from the frog.It is unnecessary to remove everything that is needed to locate and identify the frog’s organs.

Step 23: Take a look at the genitals.

There is a phenomenon known as “vestigial oviducts” on male frog’s genitals.To tell the difference, look for testes.You have a female if you don’t see them.If you have a male frog, the testes should be at the top of the body.They should be round and pale.If you have a female frog, look for the oviducts.There should be a structure outside where female frog produce eggs.

Step 24: The bladder should be identified.

The bladder is an empty-looking sac in the lowest cavern of the body, which stores urine and expels it from the frog’s body via the cloaca.This little hole is where Frogs expel waste and sperm.

Step 25: Pick out all the organs in the lab report.

If you are presented with a diagram of a frog’s organs, you will need to label it.Different labs may have different assignments for the project.If you want to get rid of your frog, you need to complete paperwork.

Step 26: Take care of your space.

As soon as you’re done with your paperwork, discard your frog.You should have a place to dispose of your dissection tray in the lab.Throw away your gloves and wash your hands thoroughly.It may take some work to get the smell off of your hands, so you may want to return after a couple hours for another scrubbing.