Trophosome

Trophosome

The trophosome is a specialized organ found in certain marine organisms, most notably in the giant tube worm Riftia pachyptila. This organ is crucial for the symbiotic relationship between the host organism and its internal chemoautotrophic bacteria, which enable the host to thrive in extreme environments such as hydrothermal vents.

The giant tube worm Riftia pachyptila and its trophosome.

Structure

The trophosome is located within the coelomic cavity of the host organism. It is composed of lobules that contain densely packed bacteria. These bacteria are housed within specialized cells called bacteriocytes. The trophosome is highly vascularized, allowing for efficient exchange of nutrients and gases between the host and the symbionts.

The ultrastructure of the trophosome region.

Function

The primary function of the trophosome is to support the symbiotic bacteria that perform chemosynthesis. These bacteria oxidize hydrogen sulfide and other inorganic molecules to produce organic compounds that serve as nutrients for the host. This process is vital for the survival of organisms like Riftia pachyptila, which inhabit environments devoid of sunlight and rely on chemical energy instead of photosynthesis.

Symbiotic Relationship

The symbiotic relationship between the host and the bacteria in the trophosome is mutualistic. The host provides the bacteria with a stable environment and access to inorganic compounds, while the bacteria supply the host with organic nutrients. This relationship allows the host to grow and reproduce in nutrient-poor environments.

Related pages

• Hydrothermal vent
• Chemoautotroph
• Symbiosis

References

• Cavanaugh, C. M., et al. (1981). "Symbiosis of methylotrophic bacteria and deep-sea mussels." *Nature* 325: 346-348.
• Felbeck, H. (1981). "Chemoautotrophic potential of the hydrothermal vent tube worm, Riftia pachyptila." *Science* 213: 336-338.

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  The Giant Tube Worm, Riftia pachyptila and its Trophosome
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  The Ultrastructure of the Trophosome Region