One of the largest concentrations of Riftia observed, with anemones and mussels colonizing in close proximity. Giant tube worms, Riftia pachyptila, are marine invertebrates in the phylum Annelida. Riftia pachyptila live over a mile deep, and up to several miles deep, on the floor of the Pacific Ocean near black smokers, and can tolerate extremely high hydrogen sulfide levels. Okeanos Explorer Galapagos Rift expedition, July 23, 2011.