During the time I spent at Planarian lab at Oxford I studied planarians collected by the lab on their recent field trip to Slapton Ley (Devon). The map below shows several locations, where four sampling populations were found.
Following species were identified in these sampling populations: Polycelis spp, Dugesia lugubris and Girardia tigrina. However, at first we were unsure of the Polycelis identity. We considered that the species could be either P.tenuis or P.nigra due to the difference in colour (brown and dark brown/black).
Therefore we launched an investigation into identifying the species and performed molecular analysis of specimens using polymerase chain reaction (PCR) and 18s rDNA marker.
Sequence analysis revealed that, what we thought were different species, were in fact the same – Polycelis nigra.
I also looked at a rate of planarian regeneration. I cut worms in to two pieces and then proceeded to take photos of them every 24 hours for four consecutive days.
After analysing series of images, I came to conclusion that Girardia tigrina seem to have fastest rate of regeneration of all.