This is one of the tadpoles from http://www.frogforum.net/breeding-eg...eveloping.html

Here he is from above (these photos are completely real - nothing faked about them, I promise):



As you may know, amphibians possess a 3-chambered heart - 2 atria and a single ventricle (mammals and reptiles have a 4-chambered heart - 2 atria and 2 ventricles - while fish have a 2-chambered heart - a single atrium and a single ventricle). In the first image below you can see the blood pooled in the ventricle of the heart. In the second image you can see the result as it is pumped out of the heart.