Deep-sea hydrothermal vents are a challenging environment inhabited by very specialized species. To reap the benefits of the local primary production, species need to cope with a number of constraints among which low oxygen is probably the most basic. This hypoxia is further complicated by the highly variable temperature these species experience. We studied the response of deep-sea hydrothermal species of scale worms (Annelida, Polynoidae) to varying levels of oxygen and showed that they were capable of compensating a decrease of environmental oxygen concentration (= oxyregulators), down to values of about 30 μmol l−1. This contrasts with shallow-water temperate species, for which oxygen consumption is directly proportional to its concentration (= oxyconformers). We measured oxygen consumption rates in 11 species from hydrothermal vents, as well as 2 species from the general deep-sea, and compared them to three shallow-water species. Life-style (free-living vs. commensal) and habitat of origin (shallow-water, deep-sea, and hydrothermal vent) did not affect oxygen consumption rates. In agreement with thermodynamic expectations, as temperature increases, oxygen consumption increases as well for all species. The sensitivity of oxygen consumption to temperature variation in the shallow-water species is however smaller than that from the deep-sea hydrothermal vent species. This unexpected result could correspond to a pronounced increase of activity (avoidance behaviour) in the vent species, which was not observed for the shallow-water species.