Polar Science 2006

Polar Science 2006 Blog

Answers to Week 4 Ice Team's Questions

Posted By: Shane_Kanatous, Dr. Kanatous on Sunday, November 05, 2006

Hi everyone,

We are so pleased to see how hard the teams are working at answering the Challenge Questions!

Here are the answers to the Week 4 Questions form the Ice Team.

Questions

Question #6: What are the terms used to describe the 4 ways in which animals lose heat to their environment?

Answer: Convection, Conduction, Evaporation, Radiation

Questions

Question #7: Given your understanding of these 4 avenues of heat loss, name the avenues of heat loss for 1) a seal holding its breath swimming under water, 2) a seal sitting in water breathing at an ice crack, and 3) a seal sitting on ice.

Answers: 1) convection, 2) convection and evaporation, 3) convection, conduction, evaporation, radiation

Questions

Question #8: Why might a seal pup loss more heat to the environment then its mother? Consider the heat loss equation for conduction: Q = k A (T1-T2)/l, where Q is heat loss, k is the conductive property of the insulation (blubber) which affects heat loss, A is the surface area available for heat loss, T1-T2 is the difference in temperature between the seal and the environment, and l is the distance separating the heat exchange objects.

Answer: A seal pup loses more heat to its environment then its mother because it has a higher surface area relative to its body size; this is called the surface area to volume ratio. The adult clearly has an overall larger surface area, but it is the ratio of surface area to volume that is important. This is because heat loss occurs at the surface area, while heat production occurs in the body, which is represented by the amount of volume for the animal. The seal pup could also lose more heat to the environment compared to its mother if its blubber is thinner (l) or if it has a poorer quality blubber for insulation (k). Also, the pup’s ability for vasoconstriction to shunt blood away from the bodies surface will affect heat loss, as this will change the temperature differential between the body surface interacting with the environment.

Good effort by the Homelearners, Cardinals and Alberta Rockies!

Dr. Shane

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