Figure 5.

(a) Ancestral state reconstruction of depth distribution in Solariellidae. Ancestral states calculated using the Mk1 model in Mesquite. Pie charts show proportion of likelihood supporting either deep or shallow water habitat. Tree topology is based on the three-calibration *BEAST tree. The presence or absence of eyes is represented graphically next to taxon name. Note that only deep-water taxa are sightless. Light penetration in the ocean varies with latitude and distance from shore. The euphotic zone, where there is sufficient light for photosynthesis to occur, varies in depth, but may extend to around 200 m in the open ocean. (b) Depth ranges for genera and clades discussed in this study, including only species used in this study.