Russell Elliott, age 11, of Nichols, South Carolina, for his question:

What is the life cycle of a shrimp?

A shrimp kindergarten, if such there be, may be invisible to the human eye. The youngsters measure perhaps 100th part of an inch, which is barely large enough to be seen, and at this stage of their larva existence, they are usually transparent. You just might be able to detect the red or black eye dots on their hungry little heads.

Shrimps are crustaceans and there are dozens of different species ranging in length from less than one inch to more than 12 inches    plus antennas. They come in greys and browns, pinks and reds, yellows, greens and blues and several species wear multi colored stripes. A few are luminescent, emitting a hazy glow. Most shrimps live in the sea, some live in brackish estuaries and a few in fresh water.

All shrimps lay eggs and molt through several larva stages, though the life cycle varies somewhat in different species. Small females lay 1,500 to 6,000 eggs at a time, larger species lay as many as 14,000. Most species produce two broods during the summer, plus a winter brood of larger eggs that take somewhat longer to hatch. In some species, the fertilized eggs are left to take their chances in the hungry sea. In others, the brood of tiny round eggs is attached to the female's swimmerets until hatching time.

The newly hatched larvae may resemble miniature pears, torpedos or almonds    plus legs and tiny dark eyes. Usually they are transparent. They feed near the surface, on morsels of floating plankton. During their first two, three or four weeks, the glassy midgets go through perhaps 15 body changes, depending upon the species.

At last they resemble adult shrimps and sink down to take up a less hazardous life near the bottom. Most species skulk on or in the sand during the day and do their foraging after dark. Some species reach maturity and old age at the end of their first year. Others mature at the age of one or two and have life expectancies of two to five years.

Their life cycles vary quite a lot, but apart from size and a few special features, adult shrimps are very much alike. The average shrimp is a decapod, a ten legged crustacean built like a miniature lobster. Its head and thorax are united under a single shell. This section is fitted with five pairs of skinny walking legs, two pairs of whiskery feelers, a pair of pincer jaws and five pairs of appendages used to handle food. The jointed abdomen section has ten swimmerets, plus two more under the tail.

The frisky shrimp can swim forward or tip down his tail to reverse his direction. He usually walks on two pairs of his back legs, tucks two pairs under his body and uses the front pair to feel his way. He hides himself by shoveling a hollow with his walking legs and jets of water from his gills, then using his whiskery antennas to flip sand over his back. All this is done with a noisy cracking of joints.