Slug or worm
February 5, 2010
This ‘slug’ was seen in my garden in Berowra which is 30Km North of Sydney.
Berowra, North of Sydney, Australia
Before we even began to research, we eliminated the possibility of this being a slug as it is lacking the sensory optic tentacles. We believed it more closely resembled a Land Planaria or Flatworm, but again, the hatchet shaped head was absent. We did a google search for “planaria Australia” and we were immediately taken to a Terrestrial Planaria website with an image nearly identical to your photo that is labeled Australian Flatworm. Sadly, clicking the link sends us back to google and does not provide any answers.
Beneath the photo is this information: “Geoplanidae -> Caenoplaninae -> Australopacifica (Dendy 1894)“. Searching Geoplanida indicates that is a new higher classification of planarian flatworms. Searching Caenoplaninae led us to a similarly shaped Planaria on Wikipedia with different coloration from Australia called a Blue Garden Flatworm. Australopacifica would seem to be a genus name, and is most probably the genus of your Australian Terrestrial Flatworm. We wish your letter had more information, including the size of this beauty. Flatworms prey upon garden snails, so they are beneficial in the home garden.