Life thriving without sunlight along tectonic spreading ridges.
AUntil 1977, marine biologists assumed every complex food web on Earth ultimately depended on solar photosynthesis. That consensus shattered when the submersible Alvin photographed dense colonies of crimson giant tube worms clustered around superheated mineral chimneys 2,500 metres beneath the Pacific surface.
BRather than ingesting organic plankton, Riftia pachyptila lacks both mouth and digestive tract. Instead, its specialised trophosome tissue houses billions of symbiotic sulphur-oxidising bacteria that convert toxic hydrogen sulphide dissolved in vent plumes into energy-rich carbohydrates—a process termed chemosynthesis.
CBecause hydrothermal vents erupt intermittently and cool within decades as tectonic plates drift, vent larvae face severe dispersal challenges across frigid abyssal plains. Genetic sequencing confirms that mobile currents carry microscopic larvae hundreds of kilometres between active ridges, seeding newly formed chimneys.
Riftia pachyptila depends on a complex internal digestive tract to consume algae.
Write ONE WORD ONLY: Symbiotic bacteria inside trophosome tissue oxidise hydrogen _______ into carbohydrates.