<meta http-equiv="refresh" content="1; url=/nojavascript/">
Skip Navigation
You are viewing an older version of this Concept. Go to the latest version.

Circulatory System

Follow the path blood takes through your body and learn where it receives oxygen and where it delivers oxygen to.

Atoms Practice
Practice Circulatory System
Practice Now
Blood From A Stone
Teacher Contributed

Getting Blood From A Stone



Student Exploration

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.

Extension Investigation

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.

Resources Cited

Image Attributions


Please wait...
Please wait...

Original text