Observation records of heterobranch sea slugs in southeastern Osaka Bay

This data set is the result of an observation conducted by the Society for Observation of Sea Slugs in Osaka Bay in the rocky coast of the southeastern part of Osaka Bay. This survey was conducted by recording the species and number of sea slugs collected by approximately 30 or more participants for several hours during low tide at spring tide. Data are published in the Bulletin of the Osaka Museum of Natural History.