The water can be as hot as 400°C (752°F) and usually contains dissolved minerals that precipitate out of them upon contact with the colder seawater, building stacks of minerals, or chimneys.

Hydrothermal vents form an ecosystem for microbes and animals; such as, tubeworms, giant clams, and blind shrimp, that can withstand the hostile environment.

The hottest hydrothermal vents are called black smokers because they spew iron and sulfide which combine to form iron monosulfide, a black compound.

For decades, oceanographers, biologists, and geologists have insisted that the only food for creatures in the deep seafloor primarily came from food particles drifting down from the surface

Until the discovery of a profusion of life at a depth of 2,500 meters (8,202 feet) in February of 1977, scientists were convinced that the deep seafloor, where darkness and cold reign, there was the earth's largest, and least known, ecosystem.

Although there were expeditions with special zoological interests up to the end of the nineteenth century, it was long considered to be a deserted environment.

Oceanographic expeditions sure that in the absence of photosynthetic production, the only food resources available in the lowest levels of the seas were those from the surface, primarily in the form of rains of particles.

So it was assumed that the abyssal plains were populated by animals that were very unusual, few in number, and normally very small.

Such concepts existed until the American submersible named Alvin dived over the Galapagos Ridge and researchers were amazed to find a profusion of life; communities of strange organisms of spectacular sizes and astonishing shapes clustered around warm springs of about ten degrees above the surrounding temperatures at the bottom of the sea.

The very first discovery of the hydrothermal vents in 1977 and the new species of organisms that the researchers found there were named in terms of what they seemed to resemble: the "giant tube worm" the "dandelion", the "spaghetti worm: and the "giant clam".

The discovery of hydrothermal vents raised the curiosity of scientists and how it was possible that a dense group of fauna can prosper in an environment characterized by toxicity, crushing pressures, and a total absence of light.

The explanation for the existence of such life was found to be based on bacteria using the chemical substances belched forth by the chimneys of the vents to synthesize organic matter, and this serves as the basis for the entire hydrothermal food chain.

Further research indicated that bacteria substitute for green plants in that dark world, and chemistry replaces solar energy. The process of primary production is called chemosynthesis, a term that parallels photosynthesis.