PASSAGE 4 NATURAL SCIENCE: This passage is adapted from Consider the Eel by Richard Schweid (©2002 by Richard Schweid).
{"Image DocumentName": "PASSAGE 4NATURAL SCIENCE: This passage is adapted from Consider the Eel by Richard Schweid (\u00a92002 by Richard Schweid).", "Image ImageDescription": "Eels hatch in the Sargasso as larvae and are carried by the ocean currents to either Europe or the United States, a journey that can cover thousands of miles and take years. Where they end up depends on which of two similar species they belong to. Those that are Anguilla anguilla invariably wind up in European rivers, and those that enter North American rivers always belong to the species Anguilla rostrata. The first person to find eel larvae in the Sargasso Sea was Danish researcher Johannes Schmidt, who published his findings in 1924, after spending 18 years hauling nets in search of eels. The known facts, as they are pretty much universally accepted among biologists and naturalists today, are that all the eels in all the rivers of eastern North America and the Caribbean countries, and all the eels in all the rivers of eastern and western Europe, are born in the same area of the Sargasso Sea, a huge area within the Atlantic Ocean, between Bermuda and the Azores, the surface of which is frequently covered with sargassum seaweed. In fact, the word Sargasso comes from the Portuguese sarga\u00e7o, meaning seaweed. The sea is about 2,000 miles long and 1,000 miles wide, set off from the surrounding waters of the Atlantic by strong currents. It includes the area known in #36popular#36 legend as the Bermuda Triangle. The larvae of both species are shaped like small oval leaves and are called leptocephali. Each leptocephalus begins to assume the form of a tiny eel, called an elver or glass eel, when it gets close to the coasts of either Europe or the Americas. By the time it reaches brackish water, where fresh and salt water mix, it is thin and transparent, hardly bigger than a hair, with a pair of eyes like black dots at one end. #33From the estuaries and mouths of rivers, the tiny eels frequently continue upstream, particularly the females, who sometimes go great distances inland. American eels have been found as far up the Mississippi River system as the rivers of Iowa. They keep going upriver until something tells them they\u2019ve reached home, and then they stop. Whatever it is that signals to eels that they are home is definitive \u2013 they settle in and live there for as long as 20 years, growing up to a yard long before beginning their journey back to the Sargasso Sea. Scientists determine an eel\u2019s age using a microscope to #33read#33 the growth rings of its otolith \u2013 a small, hard calcium deposit at the base of its skull. #33.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}