This species is found at both hydrothermal vents and cold seeps. It is the most abundant and conspicuous organism of the hydrothermal vent community on the Minami-Ensei Knoll. Development not known but most probably with planktonic larval phase.

Off Hatsushima site and Sagami Bay, central Honshu, 1170 m. Mid-Okinawa Trough: Minami-Ensei Knoll and Iheya Ridge.

Shell rather thick, stout, moderately tumid. Umbones subterminal, at about 5% anterior of the shell length. Posterior end of ligament abrupt. Extremely thick and large ctenidia with long demibranchs. No extreme mantle fusion, valvular siphonal membrane short. Anterior byssus retractor muscle scar located in the anterior part of the umbonal cavity. Pallial line smooth, concave in adult, but slightly concave in juvenile and sub-adult.

Shell length up to 107 mm.

Paratype for Bathymodiolus japonicus Hashimoto & Okutani, 1994
Catalog Number: USNM 880283
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Preparation: Alcohol (Ethanol)
Year Collected: 1991
Locality: Mid-Okinawa Trough, Minami-Ensei Knoll, Hydrothermal Vent Site, Japan, North Pacific Ocean
Depth (m): 705 to 705
Vessel: Shinkai 2000 DSR/V

Paratype for Bathymodiolus japonicus Hashimoto & Okutani, 1994
Catalog Number: USNM 880284
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Preparation: Alcohol (Ethanol)
Year Collected: 1991
Locality: Mid-Okinawa Trough, Minami-Ensei Knoll, Hydrothermal Vent Site, Japan, North Pacific Ocean
Depth (m): 705 to 705
Vessel: Shinkai 2000 DSR/V

Depth range based on 41 specimens in 1 taxon.
Water temperature and chemistry ranges based on 3 samples.

Environmental ranges
  Depth range (m): 705 - 3600
  Temperature range (°C): 1.629 - 6.604
  Nitrate (umol/L): 33.146 - 38.302
  Salinity (PPS): 34.349 - 34.675
  Oxygen (ml/l): 2.331 - 3.369
  Phosphate (umol/l): 2.368 - 2.626
  Silicate (umol/l): 72.507 - 148.729

Graphical representation

Depth range (m): 705 - 3600

Temperature range (°C): 1.629 - 6.604

Nitrate (umol/L): 33.146 - 38.302

Salinity (PPS): 34.349 - 34.675

Oxygen (ml/l): 2.331 - 3.369

Phosphate (umol/l): 2.368 - 2.626

Silicate (umol/l): 72.507 - 148.729
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.