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> Pompeii Worm
> New Domain of Life Found in Vent!
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The Pompeii Worm
A 10-centimeter (4-in.) creature from a vent west of Costa Rica is the extreme of the "extremophiles" we have discovered thus far among higher-order animals: its head basks in water averaging 22°C (72°F) while its tail withstands temperatures as hot as 80°C (176°F). Researcher Craig Cary of the University of Delaware believes bacteria that stream like strands of hair from the worm produce eurythermal enzymes, or enzymes that function over a wide range of temperatures, to help protect it from the temperature extremes.
Image © Woods Hole Oceanographic Institution
Pompeii worm.
New Domain of Life Found in Vent!
This headline is true. Methanococcos jannaschii, discovered near a hydrothermal vent in the Northern East Pacific Rise in 1982, was recently confirmed by DNA analysis to be part of the newly recognized third domain of life called Archaea. Before discovering Archaea, scientists had recognized only two domains: bacteria, or cells without a nucleus, and eukaryotes, or cells with a nucleus.
Archaea are an ancient form of life. They are cells without a nucleus, yet fully half to two-thirds of their genes are unlike anything else on earth.
Methanococcos jannaschii is a unicellular, microscopic creature that looks like a squid but, with its spinning flagella, is only 6-millionths of a meter long. It thrives in the vent environment of high heat and pressure. It consumes hydrogen and carbon dioxide for energy, nitrogen and phosphorus to make cell material, and transition metals, such as iron, nickel, manganese and selenium, for cellular functions and proteins. It produces natural methane.
Most archaea are not symbiotic, although many species are chemosynthetic. Many high-temperature archaea reduce sulfur.
Photo courtesy of David Gordon, University of Washington.
Hyperthermophilic sulfur-reducing archaea (strain 9N2), cultured from 10- to 30-degree fluids at Axial Seamount.
The discovery of Methanococcos jannaschii in a vent is one more fascinating illustration of the amazing diversity and adapability of life on our planet. Archaea have been found in a variety of extreme environments, such as salt marshes, sewer outfalls, and the hot springs in Yellowstone National Park. In fact, Archaea are now considered so numerous that, one source estimates, the domain may form up to half of Earth's biomass. They are the closest relative now known to the first life on our planet.
We can also see shimmering water ahead, a sure sign of a vent in the vicinity!
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