• Allolobophora chlorotica–Natural History Museum, London
• Worm World–Discovery Kids
• Earthworm Information–UC-Davis

As Jo pointed out, some scientists do not refer to the organs that earthworms have as hearts since they are not the same as a human heart. In some cases, they are called aortic arches or pseudohearts. Others refer to them as hearts for simplicity’s sake since they perform the function of pumping blood throughout the worm’s body.

Thanks for all of your guesses. We will have another “Spotlight On…” soon, but in the meantime, see if you can tell us who pooped.

As Earthworms are invertebrates their organs were primitive too. Perhaps these Pear shaped muscular parts started to fuse and formed a heart in vertebrates on wards most probably from Fish as those have two chambered hearts. If you look at Fish’s heart it is shaped like two joint pears.

Earthworms didn’t have a lung. Exchange of Oxygen took place through skin. This continued into Vertebrates like fish, which had gills but no lungs and Amphibians still breathe through skin while under water even though they have a pair of air sacs or primitive lungs.