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Blood carries oxygen to your tissues and waste away from them. It also helps you maintain a comfortable temperature.

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Blood From A Stone
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Getting Blood From A Stone



Why It Matters

Do Stones Bleed?

Do stones bleed? Well, no, but there is an organism in Chile that gives that impression. Watch this:

The animal is Pyura chilensis a type of tunicate (Phylum: Chordata; subphylum: Tunicata formerly Urochordata). Look here to find out more about this organism

Tunicates are unique in being able to change the direction of their blood flow.

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Use the below resources to answer the following questions

  1. What color is tunicate blood? Why does it differ from human blood?
  2. How does a ascidian tunicate heart differ from a human heart?
  3. How do the blood vessels of ascidian tunicates differ from those of other chordates?
  4. What do ascidian tunicates use vanadium (V; atomic number: 23) for? Where is it found in these tunicates? Is vanadium common in animals?
  5. What advantage do you think a tunicate gains by being able to reverse blood flow? What about the form of a tunicate makes this functioning of the heart a successful strategy for them while it doesn't seem to advantageous for other organisms? Think carefully and be as specific as you can in your answer.

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