Some species have tentacular cirri and all have unbranched parapodia. Each segment may bear setae (bristles) and parapodia (paddle-like appendages). Notopodia and neuropodia can also bear cirri which are tentacle-like projections of the parapodia. The parapodia or lateral lobes have large lamellae. The sides of the foot have evolved into parapodia, fleshy winglike outgrowths. They may have two types of setae, which are found on the parapodia. The segments of polychaete worms bear parapodia many of which carry gills. There is a muscular foot with or without parapodia (fleshy wing-like flaps). Most other species have external gills, often associated with the parapodia. Bundles of bristles, called chaetae, project from the parapodia. Scolecids have parapodia with rami that are all alike. E. Newton Harvey had noted the unusual yellow bioluminescence occurring from the parapodia. Some sea hares use their parapodia to swim. Each segment bears a pair of paddle-like parapodia. The foot has lateral projections, or "parapodia".