Acorn Worm Copepod Infection Regime

The devised re-infection regime allowed I. ptychoderae to complete its life cycle in the host tissues, enabling us to obtain post-infested copepodids for the morphological examination described below. In the re-infection study, ten individuals of P. flava were cut into 5 fragments (each about 1 cm) as surrogate hosts and infected by 10 copepodids, respectively. After infection, three infected acorn worms were sacrificed and examined every day. The acorn worms were placed in 3–5% ethanol solution for at least 4 hrs and washed with distilled water. Then, the washed water was poured through a fine net (mesh size = 100 μm) and examined under a dissection microscope. The copepods were picked up by forceps and preserved in 70% ethanol.