Tubeworms

Ridgeia Tubeworm (Ridgeia piscesae)

Ridgeia piscesae is a tube worm found in a variety of environments on the Juan de Fuca Ridge. Found in clusters up to several square meters in area, these Polychaete's lack a digestive tract, instead taking up organic carbon from symbiotic, chemoautotrophic bacteria found in their specially-evolved trophosomes. These bacteria oxidize sulfur in order to create organic material. Initially thought to be several species of the Ridgeia genus on the Juan de Fuca Ridge, genetic comparison showed that only one species existed, with various morphologies. The two extreme morphologies are the so-called long-skinny and fat-short forms.
The fat-short morphology is found around hydrothermal vent fluids, and lives in conditions of higher temperature and sulfide concentration. 15-20 cm long and around 1 cm in diameter, this morphology is flimsier, and has flanges, which can be found along the length of the tube. It has no roots, and takes sulfide in through its plume. This form is very common on sulfide hydrothermal vents within Axial Seamount’s caldera.
References:

http://eol.org/pages/393272/details