Ron Daman, age 12, of Wichita, Kan.,, for his question:
How does the crayfish multiply?
The average crayfish looks somewhat like a fancy little wagon, with eyes for headlights and legs for wheels. His jointed body is encased in acrisp shell, and his color may be pasty pale, yellowish or pinkish brown. Most creatures of this type neglect their young. Not so the crayfish. During the egg and babyhood stages of life he is tended by his mother.
Our native crayfishes enjoy life in most freshwater ponds and streams. Some are at home in soggy swamps, and a few live in sunless caves. They look like small cousins of the seagoing lobster, and so they are. All of these creatures are crustaceans, distantly related to the teeming insects. Hence, one would expect the life story of the crayfish to progress from egg to adult through some sort of larva stage. But this is not so.
The adult male and female crayfish mate in the fall. The male spreads milt, or sperm cells, onto the abdomen of the female. She then retires to a muddy bank or stream bed and digs herself down into a soggy burrow. There she lays 100 or so soft round eggs, which are fertilized when they contact the milt. The eggs remain stuck to her abdomen, between four pairs of bristled flaps called the swimmerets, all through the winter.
The female comes out at night to feed on decaying organic material. During the day, she pokes her head from the mouth of her burrow, with her pincers and whiskery antennas. There she waits to grab small creatures that happen to swim by.
Come spring, the eggs are ready to hatch. Unlike other crustaceans, which go through a larva stage, the infant crayfishes are miniature copies of their parents. They cling to the female's abdomen with tiny pink claws, looking like a crowd of glassy, dark eyed pixies, daintily tinted with pale pinks and blues.
At last they are ready to leave home. As they grow they must molt their crusty shells for larger ones and molting is a hard, risky problem. It begins when the body of a small crayfish absorbs into its blood the calciums from the shell. Meantime a soft larger shell grows under the old one.
When this is complete, the crayfish stops eating and goes into hiding. The old shell, now papery thin, cracks and peels away. The body swells up with extra water, which stretches the larger new shell and carries in the calciums stored from the old shell. The actual molting takes about six hours. As the crayfish grows, this complicated process is repeated several times.
Many of our native crayfishes get to be about 4 inches or so long. But some of the Australian crayfish are much bigger. The largest is a 9 pound whopper of Tasmania. This lobster size crayfish usually leaves the water of his forest stream and sets up housekeeping in a soggy burrow.