HOW DO AXOLOTLS LEARN?
Editor's Note: Ellie O. ('17) proposes a new project for her research involving axolotls.
I. Proposal Summary/Abstract
Axolotls are amphibians native to Mexico. They are a subspecies of salamander, differencing in their neoteny, meaning they retain juvenile characteristics. While they are common laboratory animals, not much is known about their learning capabilities. Spatial learning has not been studied much in amphibians, much less salamanders. Since it’s closely related species, salamanders, have the ability to use landmarks to locate resources, axolotls are expected to possess those same capabilities. This experiment seeks to find out whether or not axolotls have the ability to acquire spatial learning using standardized visual cues. If they are able to learn to use certain visual cues for navigation, it will give an insight into the minds and behaviors of axolotls. This can potentially help scientists uncover the way in which animals learn and function in their habitats, and with other species around them. This experiment will differ from those previously conducted on salamanders in the fact that there will be no food used to motivate the axolotl. The experiment will rely on the axolotl’s discomfort of shallow water to push it to find the escape hole to deeper water. Instead of a rock being used as a visual cue, shapes will be placed around the rig, a circular plastic container, which will also test the axolotl’s ability to distinguish these different signals.
II. Background
Axolotls are amphibians native to, and found exclusively in, ake Xochimilco in Mexico (National Geographic). Axolotls, unlike most amphibians, keep their gills and their tadpole-like dorsal fin that runs down their back (National Geographic). Since the discovery of the axolotl, they have become a model organism to understand the concept of neoteny, the retention of adolescent or juvenile traits, and regeneration of limbs (Voss, et al., 2009). They are a species of salamander and have even been identified as being a subspecies of the tiger salamander. Axolotls, while they are completely aquatic animals, have the ability to complete their metamorphosis if their environment dries up or becomes unfavorable (Voss, 2009). Psychology and learning in salamanders in general has not been explored until recently (Crane & Mathis, 2011). Spatial learning will help to get a sense of how axolotls view the world around them. This will give insight into their behavior. Exploration in animal behavior and capabilities is important to help understand nature as a whole (Frontier).
Nature has always been the inspiration for human invention and advancement in technology (Bar-Cohen, 2005). According to Bar-Cohen, biomimetics represents the “studies and imitation of nature’s methods, mechanisms and processes”. The idea of studying animal behavior allows for humans to advance, but also to understand human behavior (Snowdon, 2004). It holds the possibility of helping to explain and improve human’s relationship to their environment (Snowdon, 2004). Animals interact and behave a certain way in their environment; changes in those behaviors could indicate changes in the environment (Mench, 1998). It also helps to improve conditions for laboratory animals (Mench, 1998). By studying the intellectual capabilities of the axolotl, we can use the information gathered to propel future experiments that focus on their intellectual capacity (Crane, 2011). In this experiment, the goal is to test whether or not axolotls have the capability of acquiring spatial learning.
III. Project Description (contextualization and significance of project)
The objective of this experiment is to determine whether or not axolotls can acquire spatial learning through the use of visual cues. Since salamanders, a very similar species to axolotls, have shown the ability to use landmarks as visual cues when finding food, axolotls should also be able to do so, since they are very closely related. The axolotls will be given a certain amount of time to find an escape hole, based on standardized visual cues. and with each trial, the time will be recorded. It is hypothesized that the amount of time required for the axolotl to escape the shallow water will change based on the placement of the visual cues and the amount of trials done. The independent variable will be the placement of the standardized cues, and the dependent variable will be the time it takes for the axolotl to escape. The amount of time for the experiment and data collection will be about 2 weeks. In those two weeks, using four axolotls, 140 trials will be conducted with each axolotl. Data analysis will take one to two months to analyze all 560 trials. This experiment will be conducted on an “Inverse” Morris Water Maze. The Morris Water Maze is a rig in which a terrestrial animal, usually a rat, is put in a circular tub filled with water, with a hidden platform somewhere in the water. The objective is for the animal to find the platform and essentially learn the location of the platform. Alternatively, the Inverse Water Maze is made for aquatic animals, such as the axolotls, in which the animal is put in very shallow waters, making it uncomfortable. Instead of a platform, there will be an escape hole, which will lead the animal to deeper waters. Then a program called MetaMorph and Excel will be used to analyze the data. The success of the experiment will be determined by the change in time it takes for the axolotl to reach the escape hole. If the time decreases, it will demonstrate that the axolotls have learned where the escape hole is and will further support contentions that salamanders have the ability to acquire spatial learning. If the time increases, it will oppose the hypothesis, but will go against previous papers and their conclusions.
IV. Research Strategy
Four juvenile male axolotls of approximately the same age will be used. The axolotls will have been bought from a research center focusing on the breeding of axolotls. Each consecutive day, for fourteen days, one block, consisting of ten consecutive trials will be done on each axolotl, with each trial lasting 6 minutes. The axolotl will be put through a tube that slides it down into the rig and given six minutes to find the escape hole. There will be a camera overhead taking 3 pictures per second. If the six minutes pass and the axolotl has not discovered the escape hole, it will be gently nudged into it. The axolotl will then have two minutes rest before it is put back in for another trial. If the axolotl discovers the escape hole and goes through before the six minutes have elapsed, it will simply be put back to start over. After all the data is collected, then the pictures will be uploaded to MetaMorph to be tracked. Tracking consists of looking at the pictures of each trial, and locating where the head and neck of the axolotl is. Tracking both the head and the neck will allow for us to calculate the angle of its head. If the head is turned or tilted towards the escape hole, this could signify some spatial awareness. This information will be put in an excel sheet to determine its movement in correlation to the escape hole. The excel sheet will then be used to make graphs, demonstrating the proximity of the axolotls to the escape hole, in comparison to the other trials.
V. Bibliography
Armstrong, J. B., & Malacinski, G. M. (1989). Developmental biology of the axolotl. (pp. 176-186). New York: Oxford Univerity Press, Inc.
Bar-Cohen, Y. (2005). Biomimetics—Using Nature to Inspire Human Innovation. Retrieved from http://biomimetic.pbworks.com/f/Biomimetics%E2%80%94using+nature+to+inspire+humanBar-Cohen.pdf
Crane, A. L., & Mathis, A. (2011). Landmark learning by the ozark zigzag salamander
plethodon angusticlavius. Current Zoology, 57(4), 485-490.
Frontier, S. T. (n.d.). What Is Basic Research, 38-48. Retrieved from http://www.nsf.gov/pubs/1953/annualreports/ar_1953_sec6.pdf
Heuring, W. L., & Mathis, A. (2014, November 4). Landmark Learning by Juvenile Salamanders (Ambystoma maculatum). Retrieved from https://www.researchgate.net/publication/268157093_Landmark_learning_by_juvenile_salamanders_Ambystoma_maculatum
Mench, J. (1998). Why It Is Important to Understand Animal Behavior. Retrieved from http://ilarjournal.oxfordjournals.org/content/39/1/20.full
National Geographic, Mexican Axolotls, Mexican Axolotl Pictures, Mexican Axolotl Facts - National Geographic. (n.d.). Retrieved from http://animals.nationalgeographic.com/animals/amphibians/axolotl/
Snowdon, C. T. (2004). Significance of Animal Behavior Research. Retrieved from http://www.csun.edu/~vcpsy00h/valueofa.htm
Voss, S.R., Epperlein, H.H., Schroeder, B., and Tanaka, E.M. 2009. The axolotl. In Emerging Model Organisms. Cold Spring Harbor Press.
Warrington, Ian, Max Ringler, and Walter Hodl. "Poison Frogs Rely on Experience to Find the Way Home in the Rainforest." Biology Letters. N.p., 19 Nov. 2014. Web. 15 Aug. 2015. <http://rsbl.royalsocietypublishing.org/content/10/11/20140642>.
Axolotls are amphibians native to Mexico. They are a subspecies of salamander, differencing in their neoteny, meaning they retain juvenile characteristics. While they are common laboratory animals, not much is known about their learning capabilities. Spatial learning has not been studied much in amphibians, much less salamanders. Since it’s closely related species, salamanders, have the ability to use landmarks to locate resources, axolotls are expected to possess those same capabilities. This experiment seeks to find out whether or not axolotls have the ability to acquire spatial learning using standardized visual cues. If they are able to learn to use certain visual cues for navigation, it will give an insight into the minds and behaviors of axolotls. This can potentially help scientists uncover the way in which animals learn and function in their habitats, and with other species around them. This experiment will differ from those previously conducted on salamanders in the fact that there will be no food used to motivate the axolotl. The experiment will rely on the axolotl’s discomfort of shallow water to push it to find the escape hole to deeper water. Instead of a rock being used as a visual cue, shapes will be placed around the rig, a circular plastic container, which will also test the axolotl’s ability to distinguish these different signals.
II. Background
Axolotls are amphibians native to, and found exclusively in, ake Xochimilco in Mexico (National Geographic). Axolotls, unlike most amphibians, keep their gills and their tadpole-like dorsal fin that runs down their back (National Geographic). Since the discovery of the axolotl, they have become a model organism to understand the concept of neoteny, the retention of adolescent or juvenile traits, and regeneration of limbs (Voss, et al., 2009). They are a species of salamander and have even been identified as being a subspecies of the tiger salamander. Axolotls, while they are completely aquatic animals, have the ability to complete their metamorphosis if their environment dries up or becomes unfavorable (Voss, 2009). Psychology and learning in salamanders in general has not been explored until recently (Crane & Mathis, 2011). Spatial learning will help to get a sense of how axolotls view the world around them. This will give insight into their behavior. Exploration in animal behavior and capabilities is important to help understand nature as a whole (Frontier).
Nature has always been the inspiration for human invention and advancement in technology (Bar-Cohen, 2005). According to Bar-Cohen, biomimetics represents the “studies and imitation of nature’s methods, mechanisms and processes”. The idea of studying animal behavior allows for humans to advance, but also to understand human behavior (Snowdon, 2004). It holds the possibility of helping to explain and improve human’s relationship to their environment (Snowdon, 2004). Animals interact and behave a certain way in their environment; changes in those behaviors could indicate changes in the environment (Mench, 1998). It also helps to improve conditions for laboratory animals (Mench, 1998). By studying the intellectual capabilities of the axolotl, we can use the information gathered to propel future experiments that focus on their intellectual capacity (Crane, 2011). In this experiment, the goal is to test whether or not axolotls have the capability of acquiring spatial learning.
III. Project Description (contextualization and significance of project)
The objective of this experiment is to determine whether or not axolotls can acquire spatial learning through the use of visual cues. Since salamanders, a very similar species to axolotls, have shown the ability to use landmarks as visual cues when finding food, axolotls should also be able to do so, since they are very closely related. The axolotls will be given a certain amount of time to find an escape hole, based on standardized visual cues. and with each trial, the time will be recorded. It is hypothesized that the amount of time required for the axolotl to escape the shallow water will change based on the placement of the visual cues and the amount of trials done. The independent variable will be the placement of the standardized cues, and the dependent variable will be the time it takes for the axolotl to escape. The amount of time for the experiment and data collection will be about 2 weeks. In those two weeks, using four axolotls, 140 trials will be conducted with each axolotl. Data analysis will take one to two months to analyze all 560 trials. This experiment will be conducted on an “Inverse” Morris Water Maze. The Morris Water Maze is a rig in which a terrestrial animal, usually a rat, is put in a circular tub filled with water, with a hidden platform somewhere in the water. The objective is for the animal to find the platform and essentially learn the location of the platform. Alternatively, the Inverse Water Maze is made for aquatic animals, such as the axolotls, in which the animal is put in very shallow waters, making it uncomfortable. Instead of a platform, there will be an escape hole, which will lead the animal to deeper waters. Then a program called MetaMorph and Excel will be used to analyze the data. The success of the experiment will be determined by the change in time it takes for the axolotl to reach the escape hole. If the time decreases, it will demonstrate that the axolotls have learned where the escape hole is and will further support contentions that salamanders have the ability to acquire spatial learning. If the time increases, it will oppose the hypothesis, but will go against previous papers and their conclusions.
IV. Research Strategy
Four juvenile male axolotls of approximately the same age will be used. The axolotls will have been bought from a research center focusing on the breeding of axolotls. Each consecutive day, for fourteen days, one block, consisting of ten consecutive trials will be done on each axolotl, with each trial lasting 6 minutes. The axolotl will be put through a tube that slides it down into the rig and given six minutes to find the escape hole. There will be a camera overhead taking 3 pictures per second. If the six minutes pass and the axolotl has not discovered the escape hole, it will be gently nudged into it. The axolotl will then have two minutes rest before it is put back in for another trial. If the axolotl discovers the escape hole and goes through before the six minutes have elapsed, it will simply be put back to start over. After all the data is collected, then the pictures will be uploaded to MetaMorph to be tracked. Tracking consists of looking at the pictures of each trial, and locating where the head and neck of the axolotl is. Tracking both the head and the neck will allow for us to calculate the angle of its head. If the head is turned or tilted towards the escape hole, this could signify some spatial awareness. This information will be put in an excel sheet to determine its movement in correlation to the escape hole. The excel sheet will then be used to make graphs, demonstrating the proximity of the axolotls to the escape hole, in comparison to the other trials.
V. Bibliography
Armstrong, J. B., & Malacinski, G. M. (1989). Developmental biology of the axolotl. (pp. 176-186). New York: Oxford Univerity Press, Inc.
Bar-Cohen, Y. (2005). Biomimetics—Using Nature to Inspire Human Innovation. Retrieved from http://biomimetic.pbworks.com/f/Biomimetics%E2%80%94using+nature+to+inspire+humanBar-Cohen.pdf
Crane, A. L., & Mathis, A. (2011). Landmark learning by the ozark zigzag salamander
plethodon angusticlavius. Current Zoology, 57(4), 485-490.
Frontier, S. T. (n.d.). What Is Basic Research, 38-48. Retrieved from http://www.nsf.gov/pubs/1953/annualreports/ar_1953_sec6.pdf
Heuring, W. L., & Mathis, A. (2014, November 4). Landmark Learning by Juvenile Salamanders (Ambystoma maculatum). Retrieved from https://www.researchgate.net/publication/268157093_Landmark_learning_by_juvenile_salamanders_Ambystoma_maculatum
Mench, J. (1998). Why It Is Important to Understand Animal Behavior. Retrieved from http://ilarjournal.oxfordjournals.org/content/39/1/20.full
National Geographic, Mexican Axolotls, Mexican Axolotl Pictures, Mexican Axolotl Facts - National Geographic. (n.d.). Retrieved from http://animals.nationalgeographic.com/animals/amphibians/axolotl/
Snowdon, C. T. (2004). Significance of Animal Behavior Research. Retrieved from http://www.csun.edu/~vcpsy00h/valueofa.htm
Voss, S.R., Epperlein, H.H., Schroeder, B., and Tanaka, E.M. 2009. The axolotl. In Emerging Model Organisms. Cold Spring Harbor Press.
Warrington, Ian, Max Ringler, and Walter Hodl. "Poison Frogs Rely on Experience to Find the Way Home in the Rainforest." Biology Letters. N.p., 19 Nov. 2014. Web. 15 Aug. 2015. <http://rsbl.royalsocietypublishing.org/content/10/11/20140642>.
