Citation: Boetius A (2005) Microfauna–Macrofauna Interaction in the Seafloor: Lessons from the Tubeworm. PLoS Biol 3(3): e102. https://doi.org/
Citation: Boetius A (2005) Microfauna–Macrofauna Interaction in the Seafloor: Lessons from the Tubeworm. PLoS Biol 3(3): e102. https://doi.org/10.1371/journal.pbio.0030102
Published: March 15, 2005
Copyright: © 2005 Antje Boetius. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Since their discovery in the 1970s and 1980s, giant tubeworms at hydrothermal vents and cold seeps have fascinated biologists and laymen alike—not only for their alien morphology (Figure 1), but also for epitomizing the perfect animal–microbe symbiosis. They are among the biggest worms on this planet—some over 3 m long—yet they do not eat other organisms. Tubeworms thrive independently of photosynthetic production. They have even lost their entire digestive tract. One of the most exciting findings in early tubeworm research was the discovery that the worm's food is delivered by bacterial symbionts. The chemoautotrophic symbionts live intracellularly in a specialized worm tissue called the trophosome. They are sulfide oxidizers, using the free energy yield from the oxidation of sulfide with oxygen to fix carbon dioxide with their bacterial Rubisco enzyme. In exchange for providing nutrition for the worm, the symbionts are sheltered from grazing, but most importantly, they receive a steady source of sulfide and oxygen via the highly adapted blood circulation system of the worm. (I will never forget how horrified I was as a young student by the amounts of almost human-like blood flowing into my lab dish while dissecting tubeworms to analyze trophosome enzyme activity.) Tubeworm blood physiology, in particular the hemoglobin molecules, are tailored specifically to the needs of the symbionts. However, the host metabolism in itself is not different from that of many other animals, the main source of energy being aerobic respiration of carbohydrates. In other words, tubeworms and their symbionts need oxygen as an electron acceptor—so, after all, they are dependent on photosynthesis, the main oxygen-producing process on earth.
(A) Close-up photograph of the symbiotic vestimentiferan tubeworm Lamellibrachia luymesi from a cold seep at 550 m depth in the Gulf of Mexico. The tubes of the worms are stained with a blue chitin stain to determine their growth rates. Approximately 14 mo of growth is shown by the staining here. (Photo: Charles Fisher) (B) Close-up photograph of the base of an aggregation of the symbi