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Biological Communities

Identifies the component parts of biological communities, including living and nonliving factors, and types of biological communities.

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Blood Falls

Blood Falls

Credit: Peter West / NSF
Source: http://www.nsf.gov/news/news_images.jsp?cntn_id=114488&org=NSF
License: CC BY-NC 3.0

A bright red waterfall seeps through the Taylor Glacier in Antarctica. Called Blood Falls, it helps scientists to learn more about life in extreme environments.

Amazing But True!

  • Sea level was higher 5 million years ago and the ocean extended over more of Antarctica.
  • Ice-covered lakes are found beneath the ice in the Dry Valleys of Antarctica.
  • Conditions in the lake beneath Taylor Glaicer are extreme: high salinity, temperatures below freezing, no free oxygen, and complete darkness.
  • Credit: Zina Deretsky / US National Science foundation (NSF)
    Source: http://en.wikipedia.org/wiki/File:Blood_falls1_f_Low_Res_nsf.gov.jpg
    License: CC BY-NC 3.0

    Cross section of Blood Falls [Figure2]


  • The water coming from Blood Falls has been in the lake for about 5 million years.
  • The lake has a lot of iron scraped from the bedrock below by the glacier.
  • Snowball Earth is a hypothesis that Earth was entirely frozen sometime before 650 million years ago.

Explore More

With the links below, learn more about Blood Falls. Then answer the following questions.

  1. How could there be lakes beneath the ice in the Dry Valleys?
  2. How did the water in the lake become so much more saline than the ocean?
  3. Why do scientists call the lake a biological time capsule?
  4. Why is the water in Blood Falls red?
  5. How do the microbes in the lake breathe?
  6. Why is the existence of life in the lake important for ideas about the early Earth?

Image Attributions

  1. [1]^ Credit: Peter West / NSF; Source: http://www.nsf.gov/news/news_images.jsp?cntn_id=114488&org=NSF; License: CC BY-NC 3.0
  2. [2]^ Credit: Zina Deretsky / US National Science foundation (NSF); Source: http://en.wikipedia.org/wiki/File:Blood_falls1_f_Low_Res_nsf.gov.jpg; License: CC BY-NC 3.0

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