Dandelion

Shrimp

SUBSEAFLOOR

Crabs

Clams

Tubeworms

Octopus

Click on the words to learn more about the remarkable life forms found near hydrothermal vents.

Microbes

Hydrothermal Vent Life 

Zoarcid fish

Mussels

OctopusThere are several species of octopus that only live around hydrothermal vents. Some species have only been seen a few times. They are typically one meter long, and their heads are about the size of an orange. Octopi are top predators. They live among or even under clumps of mussels. They eat crabs, clams, and mussels.

TubewormsTubeworms live around hydrothermal vents along the Mid-Ocean Ridge in the Eastern Pacific Ocean. They can grow up to two meters long and ten centimeters in diameter. Tubeworms never leave their tubes, which are made of a hard material called chitin. The tubes help protect the worms from the toxic vent chemicals and from predators such as crabs and fish. Tubeworms do not eat. They have neither a mouth nor a stomach. Instead, billions of symbiotic bacteria living inside the tubeworms produce sugars from carbon dioxide, hydrogen sulfide, and oxygen. The tubeworms use some of these sugars as food.

Zoarcid fishThese two-foot long white fish are top predators around vents. They eat everything from tubeworms to shrimp. Despite their huge appetites, these fish are slow and lethargic. They spend a lot of time floating around clumps of tube worms and mussels.

ClamsClams colonize hydrothermal vents later than mussels. Each clam has a big muscular foot that it wedges into cracks in the ocean floor. A clam also uses its foot to move around. Just like the mussels, clams depend on symbiotic bacteria that live in their gills. These bacteria use the chemicals in the hydrothermal fluid to produce sugars. The clams use some of these sugars for food. Despite their thick shells, clams are eaten by crabs and octopi.

DandelionsThese fuzzy-looking balls are made up of a colony of numerous individual animals that hold onto each other. The animals in these colonies are related to the Portuguese-Man-O-War and other jellyfish. They use long whisker-like tentacles to anchor themselves on rocks and to move around. The dandelions are scavengers. They are some of the last animals to colonize vent sites. If there are a lot of dandelions around a vent site, it usually means that the vents are no longer active and most of the other organisms in the area are dying.

ShrimpThere are 15 species of shrimp that live around vent sites throughout the world. Roughly half live in the Atlantic and half live in the Pacific. In the Pacific Ocean, each vent site supports only one species of shrimp. They typically live around clumps of tube worms and mussels. In the Atlantic Ocean, shrimp often gather in huge swarms along the sides of active black smokers. Some kinds of shrimp are host to different kinds of bacteria that may help them gain nourishment from the hydrothermal fluids.

CrabsThere are several species of crabs that live around hydrothermal vents. One type is the Galatheid crab, or squat lobster. These white crabs live throughout the ocean, but their numbers increase around hydrothermal vents where food is plentiful. These crabs are scavengers. They hang out in mussel beds where they eat bacteria and dead animals.

MusselsMussels are very late to colonize hydrothermal vent sites. They clump together in cracks in the seafloor. Symbiotic bacteria live in the mussels’ gills. Like the microbes living inside tubeworms, these bacteria use energy from chemicals in the vent fluids to produce sugars. The sugars provide nourishment for both the mussels and the bacteria. Mussels can also filter food from the water, so if hydrothermal fluid stops flowing out of the vent, mussels can survive for a short period of time.

MicrobesHydrothermal vent microbes include bacteria and archaea, the most ancient forms of life. These microbes form the base of the food chain at hydrothermal vents. They are chemo-autotrophic, which means they make their own food through a process called chemosynthesis. This involves harvesting energy from chemicals in the hydrothermal fluids, and using that energy to make sugars from carbon dioxide or methane in the fluids. Microbes grow in the water and on almost every surface at the vents, and in tiny spaces below the seafloor. Some bacteria live in or on tubeworms, clams, mussels, and shrimp, forming symbiotic relationships with these animals.