Giant tube worm (Riftia pachyptila)

GenusRiftia (1)
SizeLength: up to 2 m (2)

This species has yet to be classified by the IUCN.

The giant tube worm is an unusual marine species, highly specialised to surviving in its unique, deep-sea environment (2) (3) (4). It lives inside a long, narrow tube, made from chitin, attaching it to the ocean floor, and possesses a retractable ‘plume’, which is extended when the animal is undisturbed. The plume is a complex structure, with tightly stacked sheets of tentacles forming a gill-like organ, and is used for taking up nutrients from the surrounding waters. The plume also has lots of blood vessels, and contains large amounts of haemoglobin, which gives it a characteristic, blood-red colour (2) (3). 

Colonies of the giant tube worm are found in the east Pacific Ocean, at hydrothermal vents on the sea floor (3) (5). Found along ridges at the bottom of the ocean, the vents are often located as deep as 2,600 metres below the surface, at places where tectonic plates are spreading apart (4).

Hydrothermal vents are like no other environment on Earth, and the surrounding habitat is unpredictable and constantly changing, subjecting the animals that survive near vent systems to extremely harsh physical and chemical conditions (5). The vents give off gases and fluids which contain highly toxic chemicals, at superheated temperatures. The giant tube worm prefers strong flowing vents, and lives in areas where the vent fluids mix with the surrounding sea water (an area where the chemical content of the water is still high, but the temperature is much cooler) (2) (4) (5).

The giant tube worm has a number of remarkable adaptations to cope with the extreme environment in which it lives. The body is split into four distinct regions, each of which has a different role in gas-exchange, anchorage and support, and the acquisition of nutrients. The trunk of the worm is found inside the chitinous tube. It is equipped with a specialised organ, called the trophosome, which is lined on the inner surface with lots of special, symbiotic bacteria, which the giant tube worm relies on to obtain the energy and nutrients it requires for growth and development. The bacteria convert the chemicals in the water surrounding the hydrothermal vents, such as sulphide, into organic material that can be used by the tube worm for nourishment (2) (3) (3). 

Because of the relative inaccessibility of the hydrothermal vents, scientists are only beginning to understand more about the ecology of the giant tube worm. As yet, very little is known about the reproductive biology of the species; however, it is thought that individuals spawn by releasing a cloud of eggs or sperm, which are dispersed upwards by a propulsion of water, caused by the worm rapidly withdrawing into its tube (6). How fertilisation occurs is not known, but the young of the giant tube worm are known to be free-living, non-feeding larvae, which later settle on the substrate surrounding a hydrothermal vent and become sessile for the remainder of their adult life (4) (5).

Although the giant tube worm is constantly threatened by the unpredictable and powerful natural forces associated with hydrothermal vents, the species is one of the most widespread, abundant and ecologically important species found in these exceptional communities (5).

On a local scale, the individual vent sites are usually fairly short-lived (a few years to a few decades) (3) (5). Underwater volcanic eruptions are a fairly frequent occurrence which can destroy whole communities, whilst vent fluids may stop flowing over time, changing the composition of the waters surrounding the vents, and having devastating effects on dependent organisms, including the giant tube worm (3).

There are currently no conservation actions targeted at this species. Scientists continue to study the giant tube worm, along with the other animals that inhabit hydrothermal vents, in order to understand more about the diverse communities that occupy this unique environment.

To find out more about the giant tube worm, see:

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  1. ITIS (August, 2010)
  2. Van Dover, C.L. (2000) The Ecology of Deep Sea Hydrothermal Vents. Princeton University Press, New Jersey.
  3. Scearce, C. (2006) Hydrothermal Vent Communities. CSA Discovery Guides (Online) Available at:
  4. Gaill, F. (1993) Aspects of life development at deep sea hydrothermal vents. The Federation of American Societies for Experimental Biology Journal, 7: 558-565.
  5. Thiébaut, E., Huther, X., Shillito, B., Jollivet, D. and Gaill, F. (2002) Spatial and temporal variations of recruitment in the tube worm Riftia pachyptila on the East Pacific Rise (9° 50’ N and 13°N). Marine Ecology Progress Series, 234:147-157.
  6. Van Dover, C.L. (1994) In situ spawning of hydrothermal vent tubeworms (Riftia pachyptila). Biology Bulletins, 184: 134-135.