|
This week's LabZone activity
June 30, 2004
Crayfish
Crayfish look like little lobsters. Both are decapods, or ten-legged crustaceans. They belong to different families, however, and live in different habitats. Lobsters are found in the ocean but crayfish are freshwater animals. They are common in rivers, lakes, ponds, and streams. Some species climb about on land at night, returning to burrows in damp soil when they are through foraging for food.
On guard!
When you approach a crayfish, it may rear up its body and open its claws. This is a defensive posture many crayfish assume when they sense a threat. Crayfish have other postures and behaviors, too. If several are put in the same container, one may dominate the others, displaying aggressive behavior until the others retreat. Some may show a preference for certain places in the tank, or have a particular response to light or food. Crayfish behavior is interesting to study, and since many species are easy to care for, you can learn more about them at home.
 | Crayfish. | Eric Engbretson, U.S. Fish and Wildlife Service. |
Rearing crayfish
You can collect your own crayfish from a pond or lake, or order a few from a supply company (see www.carolina.com/life_science/crayfish.asp (Carolina Biological Supply Company)). Keep them in an aquarium or plastic tub with a layer of clean gravel on the bottom. Some species do best in very shallow water (not quite covering their bodies) with plenty of surface area for oxygen exchange. Others will need deep water with a filter and aerator. If you collect your own, keep in mind that most crayfish do best in clean, well oxygenated water. Change the water daily if you are not filtering it; tap water is usually acceptable.
Put a few rocks in the tank so the crayfish can climb out of the water from time to time. Piled up rocks or clean clay flowerpots provide places for the crayfish to hide. If the tank is large with several hiding places, a few crayfish can be kept together. If you notice fighting or other aggressive behavior, they need more space.
Crayfish are scavengers, and will eat all sorts of food. You can offer them bits of raw meat, dog or cat food, and aquatic plants. Put the food right in front of them. If they don't start eating it within five minutes or so, remove it and try again later. Three feedings a week are adequate. Change the water after each feeding. Try feeding your crayfish in a small glass dish so it's easier to keep the tank water clean.
From Invertebrate Zoology by Ellen Doris, photography by Len Rubenstein. © 1993 Thames & Hudson Inc. (thamesandhudsonusa.com). Reprinted by permission of Thames & Hudson.
Talk Back:
Do you have any comments about this activity? Send them
to us using the form below.
|
SNK RSS Feed 
