Hydrothermal Vent Systems

Giant tube worms flourishing near hydrothermal vents completely lack a mouth and digestive tract. Instead, they depend on an internal organ called a trophosome, which is 1 by millions of symbiotic bacteria. The worm absorbs hydrogen sulphide, oxygen, and carbon dioxide through its vascularised plume, 2 these compounds to the microbes. In return, the bacteria generate organic nutrients through chemosynthesis, effectively 3 their host in total darkness.

• sustaining
• populated
• releasing
• dissolving
• damaged
• transferring

Unlike volcanic black smokers, alkaline hydrothermal fields derive their energy from chemical reactions rather than volcanic heat. The process of serpentinisation occurs when mantle peridotite reacts with seawater, releasing hydrogen gas and creating 1 alkaline fluids. These gentle emissions produce porous carbonate chimneys that build up over millennia. Because these structures maintain natural proton 2, scientists propose they served as the 3 incubators for early biochemical reactions on Earth.

• hostile
• currents
• gradients
• highly
• rarely
• ideal

Hydrothermal vents are ephemeral habitats that frequently become 1 when volcanic activity ceases. To survive, specialised fauna must 2 to freshly formed vents located hundreds of kilometres away. Most benthic organisms achieve this by releasing planktonic larvae into deep ocean currents. These microscopic larvae can enter a dormant state, 3 metabolic expenditure until chemical cues signal the presence of a viable vent field where they can settle.

• minimising
• expand
• inactive
• accelerating
• disperse
• submerged

Seafloor massive sulphide deposits formed around active and extinct hydrothermal vents contain rich concentrations of copper, gold, and zinc. As hydrothermal fluids discharge into the cold abyss, minerals 1 around the vents, gradually constructing thick ore mounds. While mining consortia view these deposits as commercial resources, marine biologists warn that seafloor extraction could 2 fragile benthic communities, causing long-term 3 to unique, slow-growing ecosystems.

• dissolve
• protect
• benefits
• disruption
• accumulate
• devastate