Lecture 11 Flashcards
Which continent is surrounded by the southern ocean?
Antarctica
What environment is Antarctica classed as?
A polar desert
What is a dry valley?
2% of Antarctica’s landmass not covered in ice. Organisms that die here are not decomposed and are exceptionally preserved
What is the invertebrate distribution in Antarctica?
No flying invertebrates
Mostly Arthropoda, spiders, earthworms and mollusks
When do seals and penguins breed? Why?
The breed in summer (October to January) as the peninsular has been exposed by melting ice
Why is the southern ocean so productive?
Constant abiotic changes occur(temperature, salinity and density due to melting ice)
Why do Antarctic algae layer in ice?
Due to their different light tolerance and nutrient requirements
What is the keystone invertebrate species in the southern ocean?
Krill
What do krill feed on?
Phytoplankton and algae frozen in ice over winter
How to fish prevent freezing in the cold southern ocean waters?
Antifreeze mechanisms, this prevents body organs from freezing when body temp goes below zero
What are the two methods of antifreeze in fish in the southern ocean?
Polyhydric alcohols (Therese are cryoprotectants) Glyceropeptides (antifreeze mechanisms)
What are ectotherms?
Organisms whose body temperatures vary with outside temperatures. Eg. Fish, invertebrates, microbes
What are endothermic?
Organisms who maintain a steady body temperature (35-42 degrees) irrespective of outside temperature variation. They are warm blooded. Eg. Mammals birds
How do endothermic keep body temperature constant?
Breathing oxygen(no Gill exposure to the cold) and by having a small surface area to volume ratio
How do Antarctic birds stay warm?give species
Thick feathers, and they are homotherms. Examples include:petrels, gulls, albatross etc
What do penguins feed on in the southern ocean?
Small Adele penguins feed on krill, larger penguins (eg empower) will preferentially feed on fish and squid but krill if they have to
How do penguins remain insulated from the cold?
Covered in feathers with an underlying insulating layer of fat. Never put their entire foot on the ice, as this reduces surface area for feet lose (feet aren’t insulated)
What is counter current heat exchange? Describe it
The arteries and veins are far closer to one another than when counter current heat exchange is not occurring. Artistries carry warm blood, veins cold blood. As they are closer together, warmth from arteries diffuses heat to veins carrying cold blood back from extremities. This causes the cold blood returning to the heart to be warmed, maintaining core body temperature.
Why do seal have blubber? (Three reasons)
For insulation, buoyancy, and to use as an emergency food reserve if needs must
What are the two types of whales in the Antarctic?
Toothless and toothed whales
What are the three toothless whales, and what do they feed on?
Baleen whale- krill
Blue whale-krill and fish (herring and mackerel)
Humpback whale- scoops fish and krill
What re the Two types of toothed whales?
Sperm whale- largest. Feeds on squid, fish sharks
Killer whale- feeds of fish, penguins, seals and young other whales
When does breeding occur in Antarctica?
Spring and summer
What are the two methods of breeding in Antarctica?
Timing breeding with the melting of ice (eg seals) or to breed in areas of free ice(common in snow petrels)
