(b) Site data

The ‘sites’ consist of 79 sites or composite sites with at least three taxa present, and include vents, seeps, whale-falls, a hydrothermal seep, and the Pleistocene Ghost City serpentinization vent site. In some cases, geographically close sites were grouped and treated as a single unit (composite site), including: seep sites in the Gulf of Mexico, the Gulf of Cadiz, off of the Caribbean coast of Colombia, and the Pacific coast of Costa Rica; vent sites on the northern and southern East Pacific Rise; and vent and seep sites in the Nankai and Okinawa troughs. A description of the sites and composite sites is provided in the electronic supplementary material, table S2. To assess the impact of water depth on the biogeographic distributions, the sites were binned into three depth ranges: less than 1 500 m, 1 500–3 000 m, and more than 3 000 m. When composite sites had depth ranges spanning two of these depth bins, they were assigned to the bin encompassing the larger proportion of the composite site's depth range.