How does oxygen enter the cells of the tube worm?

Oxygen enters the cells of tube worms primarily through their gills, which are adapted for gas exchange. These gills are often richly vascularized, allowing oxygen to diffuse from the surrounding water into the bloodstream. The hemoglobin in their blood then binds to the oxygen, transporting it to the cells throughout the worm's body for cellular respiration. Additionally, some tube worms can utilize symbiotic bacteria that produce energy from hydrogen sulfide, allowing them to thrive in oxygen-poor environments.