ECOVIEWS: Thermal vents produce bizarre life forms | Features … – Charleston Post Courier

India recently launched a rocket to the moon. Russia gave it a shot and wished they had not. Exploration rovers have crept across the surface of Mars, and Elon Musk is plotting how to get some of us there to join them. Scientists, as well as science fiction writers, tend to focus on the stars. Yet the oceans of our world offer equally interesting material. As a visiting scientist at the Smithsonian National Museum of Natural History, each day on the way to my office I passed a room with jars of what looked like 6-foot-long earthworms. They were actually from one of the strangest ecosystems known on Earth: a habitat more than a mile beneath the ocean's surface, a hydrothermal vent community.

A hydrothermal vent is an area where a major fissure on the seabed occurs between plates making up the Earth's crust. As the plates gradually separate, underlying volcanic activity reaches the ocean. As the molten volcanic rock encounters ultracold seawater, the physical and chemical reactions are impressive. Even more remarkable is that these vents are the habitat of deep-sea animals. Among the notable sea creatures are enormous, bright red tube worms. Some are as thick as a child's arm and twice as long. The tube worms stretch up from the ocean floor in clusters, waving like the tendrils of a huge organism from a science fiction movie.

On the Earths surface, natural habitats are being eliminated and many species face extinction under the assault of modern technology. Ironically, without that technology, the mysterious thermal vent communities would not have been revealed. They were discovered less than half a century ago during deep-sea exploration using submersibles that can withstand the tremendous pressure of tons of ocean water.

Natural communities on Earth ultimately receive their energy from the sun. Even animals that live in caves depend on organic materials from sunlit regions. The debris they rely on for food had its origin in green plants. But in hydrothermal vent habitats, the base of the food chain is formed by bacteria, which acquire their energy from chemical sources in the seepage area itself. In sharp distinction to virtually all other life we know about, these underworld communities function without dependency on sunlight. Although submersibles have extendible devices for picking up items, many of the vent animals are mobile, and some have never been captured. Countless species remain undescribed or yet-to-be-discovered in the worlds oceans.

Since a vent may remain active for a few decades at most, one puzzle for ecologists is how the species inhabiting the vent communities manage to persist. Where does a giant clam or tube worm that depends on nutrients in a small area of deep ocean go when the energy source disappears? Except for the fishes, most of the organisms move slowly, at best. Presumably each species has a reproductive strategy in which larvae disperse into the outer blackness beyond the vent. Most probably die in the ocean depths, but some eventually reach other vent habitats. Just as any given vent eventually ceases to exist, new ones are constantly being formed, setting the stage for colonization. The lifestyle is a precarious one, but it works, as evidenced by the similarity of species composition from deep-sea thermal vent communities around the world.

In the mid-20th century the idea of communities of numerous, sometimes large, animals living around deep-sea hydrothermal vents sounded like a creature from Twenty Thousand Leagues under the Sea. In fact, in the 1970s the first reports of vent communities seemed too fantastic to be believed. Paradoxically, although these ecosystems appear to be among the most fragile and sensitive in the world, they would rank at the top of ones least likely to be destroyed by humans. Simply studying them is difficult enough. These bizarre habitats also make the important point that to explore the mysteries of the universe, we need not look only to outer space. Plenty of opportunities for discovery await us right here on our own planet.

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ECOVIEWS: Thermal vents produce bizarre life forms | Features ... - Charleston Post Courier