Bullfrogs Hearing Capacity Essay, Research Paper

The bullfrog belongs to the family Ranidae and is commonly known for their deep resonant croaks, large body size and large ears (tympani). These frogs have a body size of 20cm/ 8in and have legs that are longer than the body (25cm/10in). They reside in the United States, Canada, Mexico, Africa, and many others in quiet lakes and ponds. Bullfrogs are very aggressive when defending their territories and do not hesitate to attack invaders, even if a frog. Being that the bullfrogs have large ears, they should be able to hear many sounds from great distances, but we shouldn’t assume this. I would like to design an experiment that would enable me to determine the range of frequencies that a bullfrog can hear using operant conditioning. Once I have determined the latter, I would like to see how well a bullfrog is able to distinguish a specific frequency from other frequencies.

For both experiments, I would need to obtain a number of bullfrogs from a natural habitat and place them in the lab made habitat, which would be similar to the one that they were removed from. Hopefully, the frogs will adapted to the new habitat and carry on as they did in their old habitat. Tampered bullfrogs such as those raised in labs or pets would not be used because the results would be inaccurate. The inaccuracy would be that these “tampered frogs” have been out of the wild for so long that they would not have the same range of frequency as those in the wild. I would first like to do this experiment on the male bullfrogs because of their deeper croaks, observe the data and then possibly repeat the experiment on the female species.

In the first part of the experiment, I want to observe whether the bullfrog can hear the frequencies sent out to it and if so will it move in the direction that the sound is coming from. Inside the new habitat there are two pathways that connect to a small platform about 2.5 inches high. The set up is high enough so that the frogs can not hop out (measurements of how high they jump will be observed and noted in order to build the design.). In front and behind the platform is a wall that the frog can see through, these walls extend out to the pathways and continue for about 1ft. At the end of the walls, the frog is free and able to roam around. The purpose of these walls are to separate the pathways so that the frog will have to chose which way the sound is coming from. There will also be two high tech speakers, one at each corner of the habitat (facing the platform) raised 2.5 inches from the habitat floor that will send out a frequency randomly from either speaker. The frequencies that I will use ranges from -250 Hertz to +250 Hertz, which will proceed in increments of 50 Hertz. Once the bullfrog completes the first range, I will use the same range but in increments of 25 Hertz and then do another experiment with the same range with increments of 15 Hertz and so on.

Once the habitat design is complete, the experiment will begin with the bullfrog on the platform and a frequency of -250Hertz sent out through one of the speakers (just suppose the left side). I will observe and record the bullfrog’s reaction; it will have two choices, to move or to stay put. If the frog doesn’t move, it means that the frequency is too low for him to hear. If the frog does move, it must decide whether the left pathway, which is the correct one, or the right pathway. If it chooses the left pathway, and then the bullfrog is rewarded with food, but if chooses the right pathway then it will not receive food. If the bullfrog responds correctly to the first frequency then I will continue with the following frequency later that day. If he fails then I will repeat the first frequency again, later that day, until he gets it correct.

In the second part of the experiment, I want to observe if the bullfrog is able to distinguish a specific frequency from other frequencies. I will attempt to do this by using the same habitat set-up as above and using a familiar call. I will use the alarm call that is made by the bullfrogs to stimulate a response. This call will be recorded at a frequency that the bullfrog can hear; this will be determined in the first part of the experiment. The experiment will begin again with the bullfrog at the platform, but with a frequency coming out of both speakers. The left speaker will have the desired alarm call at a specific frequency (suppose at 100 Hertz) and the right speaker will send an unknown frequency. If the bullfrog goes to the left pathway, than we will be able to say that he understands the difference between the two frequencies and which one is the correct one. This will then allow me to go further and not only change the frequencies but also the intensity, structure and modulation of the call in the above experiment. If the frog chooses the right pathway, it could mean that he is confused by the two frequencies. If this should happen, I would need to repeat the second part experiment until the frog was able to distinguish between the two. I would also use operant conditioning for this part of the experiment in using food as a reward and starvation as a punishment.

For both parts of this experiment, it is possible for error in that the bullfrog may not want to cooperate. This is one of the many reasons why I would use a large number of bullfrogs. Another reason for the latter is so that my results could be for the entire population.