Bill Fillmore, age 13, of Santa Cruz, Calif., for his question:
ARE THERE MANY KINDS OF EELS?
An eel is a snakelike fish. There are 22 families of eels in the world and about 350 species. All but one family live in the oceans and all except three families lack scales.
Adult eels range in length from six inches to 10 feet. Almost all eels are dull yellow, green or brown in color.
The American eel is perhaps the best known of all eels. It belongs to a freshwater family that ranges all the way from Greenland to Labrador, southward to the Gulf of Mexico and as far inland as the Mid central states.
The American eel has relatives that live in Indo Pacific and European waters. They can be found living in lakes, rivers, streams and ponds, but at spawning time they head out to the ocean, migrating to the Sargasso Sea which is located in the Atlantic Ocean south of Bermuda.
These freshwater eels go down to depths of more than 1,000 feet where the water is saltier and warmer than in any other part of the Atlantic.
On the bottom of the ocean the eels lay their eggs and then die. The eggs float to the surface and hatch into skinny, transparent larvae. The larval stage is known as the leptocephalus or "small head" stage.
In the case of the American eel, after one year the larvae reach their home shores and are ready to travel up the streams and rivers. At this stage they are about three inches long and are called elvers. The European eels take three years to return to their freshwater bases.
The males stay in the brackish waters but the females go far upstream where they remain in the fresh water for five to eight years, growing to a length of about four feet. Some landlocked eels have been known to live for 50 years. But eventually they return to the Sargasso Sea to spawn and complete the life cycle.
Eels are a highly regarded food in many parts of the world. Eels are eaten salted, smoked, marinated and jellied. They are at their best just as they start their journey to the sea.
Freshwater eels have thick capillary systems close to their skin, allowing them to absorb oxygen directly from the air or water.
When an eel heads out to the spawning grounds in the Atlantic, it may take as long as a year of drifting with the currents before the destination is reached.
A female eel on the bottom of the ocean will lay as many as 20 million free floating eggs.
In tropical oceans, the most common eel is the moray which will grow from a length of from four to 10 feet in length.