Riftia pachyptila

Geographic Range

Riftia pachyptila lives on the ocean floor near hydrothermal vents on the East Pacific Rise, more than a mile under the sea (Cary et al. 1989).


R. pachyptila lives in sulfide rich environments along hydrothermal vents on the ocean floor (Black et al. 1997, Univ. of Delware Marine Studies. 2000).

Physical Description

An adult R. pachyptila has a tough chitonous tube that grows to over 3 meters tall. At the top of the tube is a large red plume containing hemoglobin that gives R. pachyptila the appearence of a giant paintbrush . Inside the tube, the worm's body is colorless, and holds a large sack called a trophosome (along with its other organs). This sack contains billions of symbiotic bacteria that make food for the worm. The worm has no mouth, eyes, or stomach (Cary et al. 1989; Univ. of Delware Marine Studies 2000).


Females release lipid rich eggs which float slowly upward. Males release sperm bundles that contain hundreds of sperm cells. The sperm bundles then swim up to meet the eggs where they are fertilized. The larval worms swim down near the hydrothermal vents and attach to the cooled lava where they grow to form new tube worm communities. (Cary et al. 1989, Univ. of Delware Marine Studies 2000)


Larval R. pachyptila drift in the deep water, trying to find a hydrothermal vent that they can live near. They will settle down and attach to the rocky bottom when they detect the right chemicals in the water.

Food Habits

R. pachyptila depends on a symbiotic relationship with chemosynthetic bacteria for its food. Although it has no mouth or gut it is born with a mouth through which the bacteria enter. The tube worm uses a feeding sac (called a trophosome) to gather sulfuric chemicals that the bacteria uses to make food for the worm. (Univ. of Delware Marine Studies 2000)

Economic Importance for Humans: Positive


Economic Importance for Humans: Negative


Conservation Status

Other Comments

The taxonomic status of this strange group of worms is still being determined. There are several different scientific opinions about which group the species belongs to (Pearse et al. 1987; Black et al. 1997).


Brent Privett (author), Fresno City College, Jerry Kirkhart (editor), Fresno City College.


Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map


Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oceanic vent

Areas of the deep sea floor where continental plates are being pushed apart. Oceanic vents are places where hot sulfur-rich water is released from the ocean floor. An aquatic biome.


Black, M., K. Halanych, P. Maas, W. Hoeh, J. Hashimoto. 21 Aug. 1997. "Molecular systematics of vestimentiferan tubeworms from hydrothermal vents and cold-water seeps" (On-line). Accessed 07 Oct. 2000 at http://link.springer-ny.com/link/service/journals/00227/bibs/7130002/71300141.htm.

Cary, S., H. Felbeck, N. Holland. 1989. "Observations on the reproductive biology of the hydrothermal vent tube worm, Riftia pachyptila" (On-line). Accessed 07 Oct. 2000 at http://www.udel.edu/mylander/abs3.html.

Pearse, V., M. Bushbaum, R. Buschaum. 1987. Living Invertebrates. Palo Alto: Blackwell Scientific Publications.

Univ. of Delware Marine Studies, 2000. "Tubeworm" (On-line). Accessed 29 March 2001 at http://www.ocean.udel.edu/deepsea/level-2/creature/tube.html.