The earthworm and his hearts

I found an article answering my question about how many hearts an earthworm has and it is very interesting.

This article says that technically they don't have any hearts, but they have an organ that acts similar to a heart, it is called an aortic arch and yes, they have five of these arches.  They are often called hearts for simplicity's sake.

http://www.ehow.com/about_4597386_many-hearts-earthworm-have_.html

Speaking of the worm, I better go check if he is still in his cup and did not get out overnight!