Giant tube worms, Riftia pachyptila, are marine invertebrates in the phylum Annelia (formerly grouped in phylum Pogonophora and Vestimentifera) related to tubeworms commonly found in the intertidal and pelagic zones. Riftia pachyptila lives over a mile deep on the floor of the Pacific Ocean near black smokers and can tolerate extremely high temperatures and sulfur levels. They can reach a length of 2.4 m (7 ft 10 in).