Riftia pachyptila (Jones 1981)

Background
Phylum: Annelida
Class: Polychaeta
Order: Canalipalpata
Family: Siboglinidae
(Jones, 1985)

Geography and Distribution
Riftia pachyptila, commonly known as the giant tubeworm, is a type of vestimentiferan worm that is found at hydrothermal sites situated along the East Pacific Rise and the Galapagos Rift (Fig. 1) (Micheli et al., 2002; Minic and Herve, 2004). Preferring medium levels of venting with temperatures less than 30oC, R. pachyptila dominates the vestimentiferan zone (Mills et al., 2007).

Figure 1: Adapted from Vrijenhoek (2010),
Figure 1: Adapted from Vrijenhoek (2010), the red lines illustrate the broad distribution of Riftia pachyptila. This species is found at hydrothermal vent sites situated on and along the East Pacific Rise and Galapagos Rift tectonic boundaries.

They are considered ecosystem engineers – an organism that significantly modifies the ecosystem – and their recruitment at early succession stages soon allows for dense aggregations to form (Fig. 2), which then supports high species diversity as well as high species richness (Govenar et al., 2005). It increases diversity by providing a habitat to a number of species; for example, gastropod species attach to the R. pachyptila tubes (Fretter, 1988) whilst crabs and fish hide amongst the tubes of this species (Micheli et al., 2002; Desbruyéres et al., 2006). Similarly, it is can be a food resource for some predators, such as Bythograea thermydron (Dittel et al., 2005).

Figure 2: Riftia pachyptila forms dense aggreagations, domintating the vestimentiferan zone, at hydrothermal vent sites,
Figure 2: Riftia pachyptila forms dense aggreagations, domintating the vestimentiferan zone, at hydrothermal vent sites.

Appearance and Identification
Lacking a gut, mouth and anus (Jones, 1981; Minic and Herve, 2004), R. pachyptila is most identifiable by the blood red plume that is easily seen. This fused plumed region has an obvious non-ciliated groove running along its length, showing that the plume is also paired (Jones, 1981). Jones (1981) also describes the plume as looking almost feather-like (Fig. 3) with the vast number of red tentacular lamellae directed perpendicular to axis of the plume. The total length of this plume ranges is typically ranged between 11.6 – 36.0 % of the individual, though there is variability (Fisher et al., 1988).

Figure 3:
Figure 3: The branchial plume of Riftia pachyptila is described as almost feather-like as red tentacular lamellae are perpendicular to axis. Likewise, there is a clear, non-ciliated ridge that follows the length of the plume to make it paired.

This plume is normally seen coming out of the large, cylindrical tubes that R. pachyptila construct. They are white in colour, and the worm lives within it (Jones, 1981). The tube will normally indicate the length of the worm which can reach sizes of 1.5m in length (Fig. 4) and 4 cm in diameter.

Figure 4:
Figure 4: The red plume characteristic of R. pachyptila is large at <36% of total body length, and can be seen atop the large white tubes that the animal makes. As shown, it can reach large lengths of <1.5m.

Feeding Strategy
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References
Batson, P. Riftia pachyptila plume (Figure 3). Available: http://www.arkive.org/giant-tube-worm/riftia-pachyptila/image-G78008.html [09/12/2014]

Desbruyéres, D., Segonzac, M. & Bright, M. (2006) Handbook of Deep-Sea Hydrothermal Vent Fauna. Austria, Landesmuseen.

Dittel, A.I., Epifanio, C.E. & Perovich, G. (2005) Food sources for the early life history stages of the hydrothermal vent crab Bythograea thermydron: A stable isotope approach. Hydrobiologia, 544, 339-346.

Fisher, C.R., Childress, J.J., Arp, A.J., Brooks, J.M., Distel, D., Favuzzi, J.A., Macko, S.A., Newton, A., Powell, M.A., Somero, G.N. & Soto, T. (1988) Physiology, morphology, and biochemical-composition of riftia-pachyptila at rose garden in 1985. Deep-Sea Research Part A-Oceanographic Research Papers, 35, 1745-1758.

Fretter, V. (1988) New archaeogastropod limpets from hydrothermal vents; superfamily lepetodrilacea II. anatomy. Philosophical Transactions of the Royal Society of London.Series B, Biological Sciences, 319, 33-82.

Jones, M.L. (1980) Riftia-pachyptila new-genus new-species the vestimentiferan worm from the galapagos rift geo thermal vents pogonophora. Proceedings of the Biological Society of Washington, 93, 1295-1313.

Jones, M.L. (1985) On the vestimentifera, new phylum: Six new species, and other taxa, from hydrothermal vents and elsewhere. Bulletin of the Biological Society of Washington, , 117-158.

Lutz. (2013) Thermarces cerberus amongst lepetodrilus elevatus (figure 1). Available: http://archive.noc.ac.uk/chess/education/edu_dive.php [09/12/2014]

Micheli, F., Peterson, C.H., Mullineaux, L.S., Fisher, C.R., Mills, S.W., Sancho, G., Johnson, G.A. & Lenihan, H.S. (2002) Predation structures communities at deep-sea hydrothermal vents. Ecological Monographs, 72, 365-382.

Mills, S.W., Mullineaux, L.S. & Tyler, P.A. (2007) Habitat associations in gastropod species at east pacific rise hydrothermal vents (9 degrees 50 ‘ N). Biological Bulletin, 212, 185-194.

Minic, Z. & Herve, G. (2004) Biochemical and enzymological aspects of the symbiosis between the deep-sea tubeworm Riftia pachyptila and its bacterial endosymbiont. European Journal of Biochemistry, 271, 3093-3102.

NOAA OKEANOS EXPLORER (2011) Riftia pachyptila length (Figure 4). Available: http://oceanexplorer.noaa.gov/okeanos/explorations/ex1103/welcome.html [09/12/2014]

Vrijenhoek, R.C. (2010) Bythograea thermydron distribution map, from: Genetic diversity and connectivity of deep-sea hydrothermal vent metapopulations. Molecular Ecology, 19, 4391-4411.

 

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