Bristle Worm Photoreceptor Cells (image) Max-Planck-Gesellschaft Caption At first, the bristle worm larvae possess only individual photoreceptor cells on both sides of the body, called eyespots. Later, the precursors of the visual organs of adult animals form on the top of the head of the larvae. Credit Max Planck Institute for Developmental Biology Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.