Dissection data for metazoan parasites and other symbionts from vent-endemic host species collected from the 9°50’N deep-sea hydrothermal vent field.

A dataset of metazoan parasite species and counts from dissections of hydrothermal vent fauna from the 9°50’N vent field on the East Pacific Rise (EPR). Specimens were primarily collected on two research cruises, AT42-21 in 2019 and RR2102 in 2021. This dataset also includes dissection data from several preserved fish specimens collected on cruises AT15-15 in 2007 (provided by Kate Buckman and Timothy Shank) and AT37-12 in 2017 (provided by Carolyn Tepolt). Vent fauna were collected using traps, slurps, and the manipulator of HOV Alvin and ROV Jason. We provide dissection data from 2,215 potential host individuals of 51 species from the 9°50’N EPR vent field. These included 10 crustacean, 2 fish, 14 mollusk, and 25 polychaete species. Dissections revealed 12 adult metazoan parasite morphogroups and nine larval morphogroups in five major marine parasite taxa. These were two adult acanthocephalans, one adult copepod, one adult nematode, one larval nematode, one adult rhizocephalan, seven adult trematodes, six trematode metacercariae, and one trematode sporocyst. Dissections also revealed non-parasitic symbionts: several copepod species that may be commensals or micropredators, nemertean egg predators, and the commensal scaleworm Branchipolynoe symmitilida. Photographs of parasites and hosts are provided as zip files.