Studies on the chemoreception of the nemertean, Procephalothrix simulus Iwata, 1952

The feeding responses of Procephalothrix simulus Iwata to the whole-body extracts of different animals (Tubifex sp., Saccocirrus gabrillae) and single compounds (including 17 amino acids, 2 compounds related to amino acids and 2 sugars) were tested, and the response of the nemerteans with and without a frontal organ to stimulus was compared experimentally. Results showed that P. simulus is able to detect food from a distance by chemoreception. It preferred extracts to live prey, and boiled extracts were more attractive than extracts that were not boiled. Of the 21 compounds tested, 6 amino acids (glycine, alanine, isoleucine, phenylalanine, glutamine, asparagine) and betaine induced a feeding response, suggesting that they were possibly the chemical signals in the food location of P. simulus. When the frontal organ was removed, P. simulus apparently lost its selectivity, which indicated that in this nemertean chemoreception for the detection of prey was performed by the frontal organ.