Meeting Abstract
Fan worms (Annelida: Sabellidae) posses a spectacular array of distributed compound eyes on their titular feeding tentacles. These eyes govern a startle response that allows the worms to rapidly withdraw into their tubes when threatened by looming predators. While this behavior is simple and well conserved within the family, the arrangement of their tentacular eyes is quite diverse among species, with some utilizing a single pair of large consolidated compound eyes on two tentacles while others have hundreds of smaller compound eyes or ocelli scattered all over the outsides of every tentacle. How do these two different strategies manage the same behavior, and what are their relative benefits or drawbacks? Here we present neuroanatomical and behavioral data examining the wiring of these eyes into the brain. We find that these eyes make use of neural pathways not previously implicated in visual systems, lending credence to the idea that these eyes represent an independent evolutionary elaboration unique to fan worms. Furthermore we consider possible models for the visual processing of signals from these eyes for shadow and motion detection, or perhaps even low resolution vision.
