The giant tube worm (Riftia pachyptila) of the phylum Annelida is a marine invertebrate living over one mile deep on the ocean floor. The giant tube worm is usually found living on sea floor near volcanic vents known as hydrothermal vents. The giant tube worm can grow to about 2.5 meters (8 ft.), with a tubular diameter of around 4 cm (1.6 inches). The giant tube worm is a mouthless and gutless creature, which lives in a symbiotic relationship with (chemosynthetic) sulfur-oxidizing bacteria, living inside its trophosome. Before its discovery, in 1977, life forms in this inhospitable environment were not believed to exist.
The giant tube worm’s body consists of a large tubular structure attached to the volcanic substrate, which can grow up to 2.5 meters (8 ft.) in length and 4 cm (1.6 inches) across, with a vascularized red organ on one end called the “plume,” and a specialized organ within its body known as the trophosome. The red plume, which is made of hemoglobins, is used to provide oxygen from the surrounding water to the bacteria, and the trophosome is inhabited by symbiotic bacteria. The tube worm lacks a mouth, gut or anus; therefore, it must rely on its symbiotic bacteria to obtain nourishment. These bacteria convert the gases into organic compounds by the process of chemosynthesis.
The giant tube worm thrives near hydrothermal vents, where superheated magma and lava seep out at temperatures greater than 360 ° C (680 ° F) from the Earth’s crust. When the hot magma comes in contact with the cold ocean water (4 ° C), many substances, including hydrogen sulfide, methane and dissolved reduced metals get precipitated into the hydrothermal vent habitat. The hydrothermal vent is host to the giant tube worm, the sulfur-oxidizing thermophyllic bacteria, which is the primary producer in the food chain in this habitat and a number of secondary and tertiary consumers, including giant clams, crabs, shrimp and fish.
In order to live, the giant tube worm relies on chemosynthesis, which is another type of energy production, other than photosynthesis. The giant tube worm forms a symbiotic relationship with thermophyllic sulfur-oxidizing bacteria. These bacteria live in the tube worm’s trophosome. The giant tube worm absorbs hydrogen sulfide, through its plume, from the surroundings and supplies it to the bacteria, which oxidizes the hydrogen sulfide and uses the energy released in the reaction to produce the organic compounds needed for both the tube worm and the bacteria. The hemoglobins in the plume carry the oxygen inside the tube worm for respiration.
The giant tube worm reproduce when the female, Riftia pachyptila, release its eggs, which start floating upwards into the water environment. The tube worm males set bundles of sperm free. The sperm drift towards the eggs. After the eggs and sperm have joined, the larvae descend down and attach themselves to the rock at the hydrothermal vents. It is hypothesize that the giant tube worm acquires its symbiotic bacteria while in larvae development. Unlike adults, the larvae and small juveniles of giant tube worm possess a mouth and gut, suggesting that their symbiotic bacteria could have been obtained during the developmental larvae stage.
Energy at hydrothermal vents is derived from the Earth’s crust, not the Sun. Biological life thriving at hydrothermal vents obtains their energy from the chemical reactions of substances coming out from the fissures in the Earth’s crust. Some bacteria living at these vents resemble the most primitive organisms known on the planet. It is thought that life could have had an origin like the one in hydrothermal vents. According to mysticaquarium.org, tube worms are living in an environment of freezing cold 4 °C (39 °F) and extreme hot temperatures 360 °C (680 °F) that seem to replicate the origin of life.