Giant Tube Worm - Deep Sea Creatures on Sea and Sky
The HHMI film How Giant Tube Worms Survive at Hydrothermal Vents is one of 12 have a symbiotic relationship with species of chemosynthetic bacteria. Tube worms host chemosynthetic bacteria inside their bodies and use the products produced by these organisms to survive. The symbiotic relationship between. Riftia pachyptila, commonly known as giant tube worms, are marine invertebrates in the phylum Tube worms have no digestive tract, but the bacteria (which may make up half of a . "Biochemical and enzymological aspects of the symbiosis between the deep-sea tubeworm Riftia pachyptila and its bacterial endosymbiont ".Facts: Giant Tube Worms (Riftia pachyptila)
Simple rendition of sulfur circulation near hydrothermal vents Thioautotrophic mutualism Thioautotrophic bacteria obtain energy needed for biosynthesis via sulfide-oxidation, which requires the presence of both sulfur and oxygen This poses an interesting challenge in the seafloor habitat, because sulfur and oxygen are distributed in distinctive zones High concentrations of dissolved sulfur are only present in extremely hot vent fluid, while oxygen is found in the cold, ambient seawater In addition, sulfur reacts spontaneously with oxygen to form oxides, making it even more inaccessible to thioautotrophs Although this oxidation process happens at a slower rate than biological fixation of sulfur, it nevertheless decreases its availability10, This is why most thioautotrophs are restricted to the interface between the ocean and the atmosphere to compete for binding to available oxygen Thioautotroph symbionts, however, have uniquely adapted to their environment byassociating with a protective environment, i.
As a result, they are able to occupy a niche far away from the fierce competition happening at the ocean surface. Acquisition of Thioautotrophs As the tube worm matures from the juvenile stage, it seals the thioautotroph bacteria within itself by losing its mouth and developing a special organ called the trophosome 4,7, Sulfide Acquisition and Nutrient Exchange To provide the symbiotic bacteria with the nutrients they need, the tube worm synthesizes special haemoglobin that binds hydrogen sulfide independently of oxygen1,2,5, In contrast to the haemoglobin present in humans and other vertebrates, this special haemoglobin is not inhibited in its ability to bind oxygen after binding to sulfur As a result, the worm is able to provide the bacteria with both the sulfur and the oxygen needed without allowing the two to spontaneously react with each other Within the trophosome, the thioautotrophs use hydrogen sulfide and oxygen to synthesize the NADPH and ATP needed for the reduction of carbon dioxide to organic carbon Exchange of nutrients between bacterial cells and host cells The transfer of organic C from symbiont to host occurs through two possible mechanisms One possibility is that the worm subsists on organic secretions in the form of soluble organic molecules The other possibility is that the worm directly digests the bacteria Radio-labelling experiments done by Felbeck and Jarchow showed that both are likely occurring.
When purified symbionts were incubated in the presence of labelled bicarbonate, it was found that labelled sugars and amino acids were excreted into the surroundings8.
Riftia pachyptila - Wikipedia
Tube worms have no digestive tract, but the bacteria which may make up half of a worm's body weight convert oxygenhydrogen sulfidecarbon dioxideetc. This process, known as chemosynthesiswas recognized within the trophosome by Colleen Cavanaugh.
These tube worm hemoglobins are remarkable for carrying oxygen in the presence of sulfide, without being inhibited by this molecule as hemoglobins in most other species are. The chemosynthetic bacteria within the trophosome convert this nitrate to ammonium ions, which then are available for production of amino acids in the bacteria, which are in turn released to the tube worm.
Giant tube worms Facts
To transport nitrate to the bacteria, R. The exact mechanism of R. This reaction provides the energy needed for chemosynthesis. For this reason, tube worms are partially dependent on sunlight as an energy source, since they use free oxygen, which has been liberated by photosynthesis in water layers far above, to obtain nutrients.
In this way tube worms are similar to many forms of ocean life which live at depths that sunlight cannot penetrate. However, tube worms are remarkable in being able to use bacteria to indirectly obtain almost all the materials they need for growth from molecules dissolved in water. Some nutrients have to be filtered out of the water. Tube worm growth resembles that of hydroponically grown fungi more than it does that of typical animals which need to "eat".