A deep-sea hydrothermal vent is a fissure on the ocean floor from which geothermally heated water emerges, most found along mid-ocean ridges. They are considered one of the earliest types of environments to have existed on Earth, marking a feature of our planet and its oceans since the Hadean era. Deep-sea hydrothermal vents are home to highly productive communities of specially adapted fauna that rely on chemosynthesis and geothermal energy. Riftia pachyptila is a species that has garnered significant attention from scientists, and its way of life and survival at vents have been extensively researched. R. pachyptila is a deep-sea giant tube worm that inhabits environments rich in sulfides along hydrothermal vents on the Pacific Ocean floor, belonging to the family Siboglinidae. Due to the specific environment in which R. pachyptila lives, it has developed a range of adaptations that enable it to survive and thrive. Its soft body is divided into four regions, protected by a narrow, elongated tube made of chitin. Given the nutrient-poor nature of these habitats, R. pachyptila enters symbiosis with chemosynthetic bacteria. Chemosynthetic bacteria oxidize sulfides to obtain energy for CO₂ fixation. Individual R. pachyptila worms are separate sexes, fertilization is external-internal, and they develop through a larval stage that aids in their dispersal.