8 November, 1997
8 November 97
Condition III all locations.
REGIONAL WEATHER SUMMARY...A low north of Marie Byrd land is moving west-southwest and will increse the southerly winds over the McMurdo area.
TODAY: Mostly cloudy becoming cloudy during the late afternoon. Visibility: Unrestricted.
Wind (knots): Southeast 10 to 20 increasing to 20 gusting to 30. High: -07C/+19F Lowest Wind-chill -29C/-21F
TONIGHT...Cloudy with light snow and blowing snow developing by early evening
Visibility: Unrestricted lowering to 1/2-2 miles.
Wind (knots): Southeast 20 gusting to 35.
Low: -09/+16F Lowest Wind-chill -32C/-26F.
SUNDAY...Cloudy. Snow and blowing snow developing in the morning. Visibility: Unrestricted. Lowering to 2-6 miles in blowing snow.
Wind (knots): Southeast 25 gusting to 40.
High -06C/+21F. Lowest Wind-chill -29C/-21F.
SCOTT BASE 24HR TEMPERATURE FORECAST
Low: -11C High: -08C.
Next sunrise in February, 1998
YESTERDAY'S EXTREMES: 07 November, 1997
Maximum Temperature: -03C/+27F
Minimum Temperature: -08C/+18 F
Peak Wind: 40 Knots
Lowest wind chill: -29C/-21F
Well, this was another routine day. I repeated the experiments from yesterday and this time the data looked better. I can now look forward to doing the same thing another time. I will keep determining the respiration rate and protein concentration of individual tube feet at various temperatures until I have enough data to draw some conclusions about the effect of temperature on the respiration rate of starfish tube feet.
The overall goal of this research team is to try to understand the metabolic biochemistry of these Antarctic echinoderms. The larvae of these Antarctic sea urchins and sea stars may live up to a year without food. Their natural food source, phytoplankton, is not available to them most of the year because the frozen sea ice is more than 6 feet thick and effectively blocks out the sun. Not only do these larvae need to function in subfreezing water, but they must exist and develop in the water column without food. In their natural environment of McMurdo Sound the eggs hatch months before the sea ice melts. This survival strategy for hatching and developing without food may be unique to Antarctic echinoderm larvae. It is one part of the story of their adaptation to this extreme environment.
Since tube feet are so important to the survival of a sea star (locomotion and feeding) it will be interesting to understand how much of the organism's energy budget is devoted to this activity. It will be important to understand how temperature affects the respiration rate and to relate this to the effects that temperature has on the citrate synthase enzyme involved in cellular energy production.
Tomorrow, weather permitting, we will go out on the ice to Cape Evans to dive for more sea urchins. This will take all day so I'll plan for another experiment on Monday.
Things to ponder:
The environment is always changing. Sometimes these changes are slow and take place over millions of years and other times the changes are rapid and may be the result of catastrophic events. Antarctica contains fossils and other evidence that it was once very different than it is today. There are fossil forests and even fossil dinosaurs in Antarctica. As the sea floor spread and Antarctica became separated from the other continents an ocean current developed around Antarctica. It is known as the Circumpolar Current because it flows around the continent. About 20 million years ago it had the effect of cutting off Antarctica from the other ocean currents which formerly brought warm air. This is known as the Antarctic Convergence and resulted in the thermal isolation of Antarctica.
As a result of this thermal isolation the climate of Antarctica became colder and eventually led to the formation of a permanent ice sheet, permanently frozen ocean, and water temperarures which are always below the freezing point of fresh water. Any life which was to survive these changes would need to evolve very different adaptations and survival strategies. Scientists, like those of my research group, are now able to study Antarctic species and their adaptations to this extreme environment.
A common misconception concerning evolution is that one kind of living thing can change into another. For example, some people think that a fish may develop into an amphibian, an amphibian may become a reptile, and so on. This simply is not so! Anything born a fish will die a fish.
So how does adaptation and evolution occur? Most people know that the answer involves the process called natural selection. Natural selection means that certain members of a species are able to pass on more of their DNA to future generations than other members. This means they produce more surviving offspring. If this happens over many many generations the group can become very different from the original group if there is a survival advantage for that type of DNA. This is known as adaptation. As adaptations accumulate over time the differences may become so great that the group can no longer produce fertile offspring with the original type. If this happens a new species has evolved.
1. Penguins are found only in the Southern Hemisphere. Using the information above develop a possible explanation why this is so.
2. What are some of the adaptations penguins have?
4. Using the information above develop a possible scenario which explains the origin of the 18 known species of penguins.
5. Why do you think only 4 species of penguins are found in Antarctica?
6. One species of penguin, the Galapagos penguin, is actually found on the Equator and lives only on the Galapagos Islands. Using the information above develop a possible scenario which explains how this might have evolved.
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