nervous, reproductive, digestive and excretory system of planaria flatworm

nervous reproductive digestive excretory system planaria flatworm nerves anatomy ganglia animal physiology biology structure part morphology worm illustration vector scheme schema isolated white background set ovary gonopore testes seminal vesicles female male pharyx gastrovascular cavity tract digestion cilia tube cell protonephridia secretory urinary protonephridium nephridia nephridium flame n