Preventing Penguins from Losing Heat: an Experimental Overview

Introduction

The survival of any population relies on multiple different factors, a combination of both abiotic and biotic. Over time, Emperor Penguins have developed a cooperative behaviour strategy that ensure the survival of individual penguins and the population itself. Due to the fast rate heat is lost in the Antarctic, a sole penguin is at risk of freezing to death. Penguins huddle together in an attempt to keep themselves warm, and can reach temperatures of 20?, despite the temperature of the environment reaching as low as -50? (Gammon, 2012). By huddling together, they decrease their surface area to volume ratio. A huddle of penguins has a limited amount of the surface area of the overall volume open to the elements. A penguin that is isolated and alone has a larger surface area compared to its volume. Surface area is a vital aspect in the transfer of heat. The larger the surface area to volume ratio, the more heat can be lost through it. By creating a huddle, penguins reduce the amount of heat they can lose to the environment due to the reduction of surface area.

For populations to be maintained in an ecosystem, there must be access to a combination of biotic and abiotic factors. Examples of biotic factors necessary for the survival of penguins are fish, krill and squid for food, despite the fact they can last without food for up to 100 days. The most pivotal biotic factor essential to their survival is other penguins. These protect them from any life threating abiotic factors in the environment, such as temperature and wind. Isolated penguins are more at risk of suffering from abiotic factors due to the larger amount of surface area that can be compromised. The penguins on the outside ring in the huddle will not be as greatly affected as the sole penguin, as they have a lesser surface area open to the abiotic factors. The penguin’s least affected would be the inner penguins as they have a very small surface area available. Huddling is a form of behavioural adaptation, where the penguins changed their actions to better suit the environment. If a penguin was subjected to the harsh temperatures and wind of the environment, it could cause a rapid decline in their body temperature, affecting their nervous system and bodily functions. The overexposure of the penguins in this environment causes the heart and respiratory system to fail causing their death. Homeostasis is a self-regulating process that allows animals to keep the optimal internal environment for survival. (Encyclopedia Britannica, n.d.) An isolated penguin will need to increase its body temperature to survive. Homeostasis increases the body temperature by sending a message to the temperature regulating centre of the brain, the hypothalamus. Temperature receptors in the skin send the message, the nervous system then sends it to the effector, in this case the penguins muscles. The penguin’s response is to shiver in order to try to increase the body's temperature. (ABPI, n.d.)

However, overexposure for an isolated penguin cannot be helped by the process of homeostasis as heat cannot be gained as quickly as it is lost. (Mayo Clinic, n.d.) This will cause the isolated penguins to die.

Experiment Design

The aim of this investigation is to determine the effect varying protection has on the heat loss of penguins. Test tubes will be used as a substitute for penguins in this experiment. The hypothesis is: as the protection of the test tube decreases, the temperature loss over time will increase. The isolated test tube will lose heat the fastest.

Independent Variable: amount of protection

Dependent Variable: Temperature change of water

Constant Factors:

· Amount of water placed in each test tube

· Size of each test tube

· Time the test tubes were used

· Initial temperature of the water that was placed in each test tube

Materials:

• 500ml beaker x2
• Warm water
• Test tube rack
• Thermometer x3
• Timer
• Rubber bands x2
• Test tubes x 15

Method:

1. 14 test tubes were grouped together and secured with two rubber bands, one at the top and one at the bottom.
2. The group of test tubes were placed in a 500ml beaker.
3. The warm water was poured into the 14 test tubes to the same level, also filling the isolated test tube to the same level.
4. The 14 test tubes were transferred into a new empty 500ml beaker and the isolated test tube was placed in the test tube rack.
5. A thermometer was placed in the isolated test tube, the innermost test tube and a test tube on the outer ring.
6. The initial temperature was recorded.
7. The temperature of the test tubes of water were recorded every minute for 10 minutes.
8. The change in temperature from the initial temperature of the water was calculated and recorded.

The initial temperature for each test tube was 34 degrees Celsius. The plot on the graph that decreases in heat over time the most is the isolated test tube plot. The isolated test tube lost 27 degrees within 10 minutes. The temperature of the isolated temperature plateaus at 7 degrees from 7 minutes. The outer test tube lost a total temperature of 15 degrees Celsius and the temperature did not plateau. The central test tube lost the least amount of heat, only losing 10 degrees during the whole 10 minutes. The temperature dropped steadily throughout the time period.

Discussion

The results obtained from this experiment were similar to what was predicted. The water placed in the isolated test tube representing the isolated penguin lost the most heat throughout the experiment. This is because of the increased exposure to the cool environment in collaboration with the large surface area of the test tube. The surface area of the isolated test tube was much bigger than the volume of water within, meaning more heat could escape over time due to the large surface area to volume ratio. The water on the outer ring of the huddle lost the second most amount of heat. The least amount of heat was lost from the test tube in the middle of the test tube huddle. This was predicted as the outer ring test tube has a smaller surface area to volume ratio than the isolated test tube and a larger surface area to volume ratio than the central test tube. The central test tube lost the smallest amount of heat due to the smallest surface area to lose heat from.

Despite the results that were gathered being predicted before the experiment, there were multiple unexpected data points. It was not expected that the isolated test tube would plateau at 7 degrees. However, it was expected for the isolated test tube to rapidly decrease in heat and eventually plateau, but it was assumed this would happen at room temperature. The other two measured test tubes did not plateau, which was also expected as these test tubes held in more heat.

There are a few different sources from which random error could occur throughout the investigation. One of those includes the water in the test tubes was not measured accurately with a measuring cylinder, but by observation. The experiment required the water to be measured by eye rather than a cylinder, as transferring the water between the different containers would have meant a definite loss in heat and would have significantly reduced the accuracy of the data. This remains an error as it is not known whether the quantity of water was the same in each test tube. If each test tube contained a different quantity of water, the volume would not be the same effecting the loss of heat. A second random error could have been that the temperature on the thermometer was read incorrectly. Due to more than one person in each experimental group taking down measurements, people could have read the thermometer differently each time. This means the recorded temperature could have not been the true value, severely affecting the results of the experiment. A systematic error that could have potentially occurred could be that the thermometer used was not correctly calibrated. This means the results recorded would not be accurate, but the trend in the data would still be visible.

There was only a very small sample size used during this investigation. There were only the isolated, outer ring and central test tubes that were actually measured, and no repetitions were made. Due to these factors, the effect of random errors would be more prominent and significant. In an experiment like this, it is vital that it is repeated and with a larger sample size in order to reduce the amount of random errors. The more values recorded and averaged would mean any outliers of the data would have a less significant impact. As there are no true values for this experiment and no replicates were made, the accuracy and the precision cannot be discussed.

One of the strengths of this experiment was the temperatures of each test tube that were recorded were done with a thermometer with a resolution of one. This means the thermometer was accurate in reading the temperature of the water. Another one of the strengths of this investigation was that the experiment was carried out with each test tube at the same time and in the same environment. This meant that the external factors affecting the test tubes would be affecting them at the same rate. There would be no variation in temperature in the room so the test tubes would not be dramatically affected.

However, despite the strengths of this experiment, there were also multiple weaknesses. One of the weaknesses was that the thermometer could have been read differently by each person who was recording any results. This means the readings would not be true to the experiment, and would affect the results and the conclusion. Another weakness includes measuring the water in each test tube without a measuring cylinder. It was important for all the quantities to be the same in each test tube, in order to get an accurate result when it came to the rate in which the heat was lost. Without the accurate measurements, the amount of heat loss would vary depending on the different volumes. A third weakness was the thermometer not being calibrated accurately enough to read the temperature to a specific degree. This can be identified as a weakness as the true temperatures of the water would not have been reflected in the results. Conclusions could still be drawn; however, the values would be incorrect despite the trend of the data still being correct. The small sample size and lack of repeats in the experiment was another pair of weaknesses that reduced the significance of the data. The effect of random errors was increased due to this. The most significant weakness of the whole experiment was that the test tubes in no way accurately represented how penguins lose heat, whether huddled or isolated. The layer of fat and feathers possessed by penguins insulates them from the cold, as well as the huddle formation, not represented well by the glass tubes.

One of the improvements that could have been made to the investigation was to find another substitute for a penguin other than a glass test tube. The replacement apparatus would still need to be able to work effectively to gain results. Another improvement would be measuring the amount of water in the test tubes with a measuring cylinder. A third improvement would be using the same person to read the thermometer each time and record the data in order to gain a more accurate result. It would remove the chance of random error associated with thermometers. Testing the calibration of the thermometer would also be an improvement as it would take out the systematic error in the investigation. By testing the calibration with something of known value, the accurate temperature of the waters can be recorded.

Conclusion

The results of the investigation effectively reflected the hypothesis, showing the ways in which the location of the test tube in the huddle affected the rate of heat loss. However, due to the use of test tubes in replacement of penguins, it is impossible to see if this is in fact similar to the rate in which penguins really do lose heat. The experiment was valid, as the results demonstrated the way temperature is affected when it comes to surface area and volume ratio. Due to the large amount of biology behind the loss of temperature over time, there were very little errors while carrying out of the experiment, portraying the experiment as reliable. It is reliable because if the experiment were to be completed again, the same results would be seen each time the experiment was carried out.