1. Why Don’t Fish Freeze
By:Rachel Brayley

2. Why do some fish need antifreeze? Who needs it? How does it work?
Other adaptations to the cold.
What can be done with antifreeze?

3. Why do some fish need antifreeze?
Live in Antarctic Ocean
Water less than 0°C
Always at or below freezing point
Ice crystals in water

4. Ice crystals
Problem? X

5. Who? Antarctic fishes Antarctic cods Icefishes Antarctica
South pole
Antarctica
North pole or South pole?

6. Antarctic cod Largest of the Antarctic fishes Grow up to 5 feet
Average weight 55lbs
Mostly a benthic fish
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7. Icefishes Snout projects forward and is depressed Pelagic
Also called “whiteblooded” fish
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8. Similar? Crocodile Icefish Credit:http://www.botswana-tourism.gov.bw
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9. So why don’t they freeze?
Antarctic cods
Protein “antifreeze” in blood
Lowers the freezing point of body fluids below the freezing point of the seawater
Attach to and prevent the further growth of ice crystals
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10. Ice crystals
Prevention

11. Another adaptation to the cold
Icefishes
Doesn’t keep them from freezing
Lack hemoglobin in blood
Evolved without it because don’t need it
What is hemoglobin??
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12. Hemoglobin Part of red blood cells Transports oxygen in blood O2
Organs Cells, etc.

13. How do they live without it?
Transport oxygen with plasma instead
Able to do because:
Live in highly oxygenated environment
Excellent blood circulation
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14. What can be done with fish antifreeze?
Winter Flounder
Cold stimulates production of antifreeze
Antifreeze gene
Atlantic salmon growth rates
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15. What have we learned?
The 2 kinds of fishes that have adapted to extremely cold water are:
Antarctic cods
Icefishes
These fish live in the:
Antarctic Ocean
What is the adaptation that Antarctic cods have that keeps them from freezing?
Antifreeze proteins
What have Icefishes evolved without because they don’t need it?
Hemoglobin
What kind of fish are antifreeze genes from Winter Flounder being used in?
Atlantic Salmon

16. Questions??