Reading 2

Unit 9- Reading 2

Page 137

Exploring the Deep Ocean

Alvin can dive to ocean depths of 20,000 feet- nearly four miles down. Alvin can rest on the ocean bottom or hover at middle depths for up to ten hours, taking photographs and performing underwater experiments. Alvin is amazing. Many of the 150 to 200 dives Alvin makes annually result in underwater discoveries of unusual sights never before seen.

FACTS ABOUT ALVIN

Alvin is not a man. Alvin is a deep-sea submersible craft capable of carrying up to three occupants. It is owned and operated by the Woods Hole Oceanographic Institution on the east coast of the United States. Alvin was built in 1964, but it has been upgraded and reconstructed many times since then. Alvin’s titanium hull, or outside shell, is built to withstand the impact of the immense pressure of the deep ocean.

Alvin weighs 37,400 pounds and is 23 feet 4 inches long. It has a six—mile range and a top cruising speed of two knots. Five hydraulic thrusters propel the craft, and lead—acid batteries power the electrical system. Inside is an infinite variety of the latest electronic equipment, including a gyrocompass, a magnometer, and a computer terminal.

Alvin allows researchers to conduct underwater biological, chemical, and geological studies. Special lamps shine light into the black water so observers can see the wonders of the underwater environment. Cameras are mounted on the outside to take underwater photographs, and two external “arms” enable researchers to collect underwater samples.

ALVIN’S AMAZING DISCOVERY

One day in 1977, Alvin contributed to an amazing discovery. On that day, Alvin was transporting scientists on a routine study. The craft was one and a half miles below the surface of the sea near the coast of the Galapagos Islands.

As they looked through the three 12-inch portholes, the scientists were temporarily stunned to see a strange underwater landscape littered with what looked like chimneys. The chimneys were discharging clouds of black smoke into the surrounding water.

Clustered around the chimneys was an aggregation of odd creatures that lived totally cut off from the world of sunlight. The scientists were looking at him hydrothermal vents and the strange sea creatures that exist near them—an entire system of life based not on sunlight, but on energy from the earth itself.

STRANGE SEA CREATURES

An unusual kind of animal life exists around these vents. Among the chemicals pouring out of the vents is hydrogen sulfide, a gas that is poisonous to most land-based life. However, bacteria in the seawater near the vents feed on this gas and other dissolved chemicals and minerals pouring from the vents.

Then tiny animals feed on the bacteria, and these tiny animals ultimately become food for still larger animals. Giant red and white tube worms eight feet tall cluster near the vents and dominate the scene. Tiny shrimps and white crabs Ocean life growing near the vents as feed on the worms while giant clams rest in the sand. In an environment that seems incompatible with life, these creatures are thriving.

WHAT IS IN THE FUTURE’?

Since the first vent was discovered in 1977, hundreds of other vents have been located in oceans around the world. In 2008, a cluster of five vents so was discovered in the Atlantic Ocean between Greenland and Norway. Some of the sites are inaccessible, so scientists have not been able to study them all.

However, scientists are planning to trace the development of vents by revisiting some they studied earlier. They want to find out if the vents will erode or remain active over time and if the odd creatures as will change.