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In this lab we will be dissecting a frog to study the frog's internal organs to develop dissection technique and to observe organ system of a representative vertebrate. Frog are interesting because they live both in and out of water. they also play a big part in ecosystem evaluation. Since their skin is so moist and they absorb things, they have the ability to absorb nutrients from their environments. This seems like an advantage, but it also lets them absorb toxins that makes them a miner's canary for changes in the environment. Frog's are also the first vertebrates we will be dissecting, and I anticipate that they will be more interesting than the starfish and clams since they have more developed internal systems like nervous, digestive and respiratory systems. They are also the first dissection subject we've had with a brain.
It was hard first to determine the sex of our frog but after removing the organs we saw the ovaries. The brain is differently shaped than expected. The bones look like tiny chicken bones. The muscles on the legs are very strong and made of a fibrous material. The eyeballs are hard in the center. Strangely the tongue is attached in the front.
Questions:
1. How can you tell the difference between male and females frogs??
*Males have testes and adhesive thumb pads on each foreleg to grasp the female during mating. Their tympanic membranes are larger than their eyes, and they have two kidneys.
*Females have ovaries and a uterus. Their eye and tympanic membranes are about the same size and they only have one kidney.
2. What is an unusual feature about the frog's tongue?
*A frog's tongue is attached in front. It also flicks out at great speed, curls around the prey, then flicks back into the mouth with the doomed dinner.
Conclusion:
In this lab we dissected a frog to see its internal organs, and to observe it's circulatory, digestive, and reproductive systems. The frog was wonderful compared to our previous specimen, the clam. The organs of the frog were all in the right place and easily identified. The reproductive system was a bit hard to distinguish between male and female. But after close scrutiny we all decided that it looked more like a female than a male and at the end of the dissection we found the ovaries which confirmed our suspicions. An interesting thing I found out is that the frog's tongue is connected in the front, I imagine so that it can flip it out faster than if it were connected in the back. This being our first specimen with a brain it was interesting to see how it was shaped. The oblong form was different than I expected, yet when I found out what everything did, the placement of certain lobes made sense. The frog had a spine but no rib cage which would make it vulnerable to attack from the side. Considering how frogs live, with thier stomach to the ground I can see why they would value a spine more than a rib cage. The spine provides protection from assult from above wich would be the most common attack. The frog in all was an interesting dissection. I look forward to our next specimen. But I don't think it will be as clearly identifiable as the frog's organs were.
