Warning colouration in pseudocerotid flatworms (Platyhelminthes, Polycladida). A preliminary study

Many species of tropical and subtropical pseudocerotid flatworms are noted for their brilliant colour patterns and conspicuous behaviour and are suita ble candidates for the investigation of aposematic colouration. This study gives the first experimental evidence of aposematic colouration in pseudoce rotid flatworms. Coloured and uncoloured agar models of flatworms were used to determine whether a fish predator, the moon wrasse thalassoma lunare, c ould learn to avoid colourful flatworms on the basis of their colour patter n. The results showed that uncoloured models were more significantly attack ed than coloured models (1% significance) and that there was no significant difference between attacks made to live flatworms and their respective mod els. These results clearly indicate the operation of aposematism in brightl y coloured flatworms and demonstrate the operation of mimicry as the agar m odels were essentially non-living mimics of the flatworms.