A Science Experiment With Crayfish

Crayfish. Crawfish. Crawdads. What you call them depends on where you live. For those unfamiliar with this type of animal, crayfish are crustaceans that resemble tiny lobsters. They come in a variety of colors, and are generally a few inches long, although the biggest ones can be a couple feet long and weigh several pounds. In the past, we successfully raised and released butterflies and frogs. Now it was time to learn about the characteristics of living things in more depth; specifically, how living things change and respond to their environments. Naturally, when my children saw crayfish in a tank at our local pet store, I agreed to buy one because I knew we had found a new science project.

Our Science Experiment With Crawfish

Their crayfish education began on the ride home. When my son reached down to touch his new pet, it pinched his finger and refused to let go. Lesson one: treat all animals with respect, and learn to handle them correctly. Once the tank and pump were set up, we sat back and watched our new pet. Crayfish are fascinating to observe because they have an amazing array of legs, pincers, and other appendages. They use these appendages to simultaneously walk, eat, feel, and grab their prey. The latter use was the one my son unwittingly discovered in the car. Crayfish also have an acute sense of hearing and smell. This was immediately apparent when we saw it scuttle backwards under a rock whenever our dog sauntered into the room.

Making Predictions and Graphing Results

Without even realizing it, the children were starting to do investigative science. As the weeks went by, they made predictions about the crayfish’s behavior, then designed simple procedures to test them out. For example, they wanted to know how a crayfish might behave when given the choice of a shelter or no shelter. They observed it at regular intervals during the day and night over a two-week period, then graphed the data. Next, they compared their predictions to the results. This led to a discussion about animal adaptation; specifically, how crayfish adapt to their environment in order to increase their chances of survival.

The Life of Our Crayfish

We would also watch in wonder as our crayfish climbed up to the top rock and hid patiently behind a plant, until an unsuspecting minnow swam past. Then he would launch himself off the rock to snatch up his meal. What a great opportunity to discuss the terms food chain, predators, and prey! We also looked at crayfish habitats in the wild, and got out the map to see where different types of crayfish live in the world. Over the course of the next few weeks, we drew crayfish anatomy, learned about its reproductive cycle, and watched in wonder as it experienced its first molt. In fact, we covered so many educational topics relating to crayfish, I’d forgotten about the emotional side. Hence, it came as quite a shock one morning when my son discovered it dead in the tank. Even in death, the crayfish taught us another important lesson about the cycle of life. We held a ceremony, followed by a burial in the backyard. The whole family gathered around, even the dog. Somehow, our ceremony seemed curiously fitting for the little creature who had such a big impact on our family's life. Here are some terrific lessons on crayfish and investigative science.

Animal and Crayfish Lesson Plans:

The External Anatomy of the Crayfish

Students study the external structures of a crayfish. They complete a short quiz, and label these structures on a diagram.

Wanted Dead or Alive!

Students identify characteristics of living and nonliving things through oral and written testing.

Animal Adaptations: Physical Characteristics

Students design and construct a habitat for an animal with a specific adaptation.