Signals at the Coral Arch

The Coral Arch Observation

Ms. Chen's class watched a group of cardinalfish in a classroom coral reef aquarium. The fish often rested near a model coral arch. The class defined a response as swimming toward the arch within ten seconds after a cue began. Students recorded what they could see from outside the tank. They did not know what happened inside a fish's brain.

For each trial, a student moved a silver disk beside the tank or kept it behind an opaque panel. In some trials, a small speaker beside the tank played a soft chime. The speaker did not touch the tank. The students kept the fish group, the arch, the ten-second time, and the distance from the tank the same. They changed which cues were available.

The class recorded twelve trials in each condition: a moving silver disk was visible and the tank was quiet: 9 responses; the disk was hidden and the tank was quiet: 2 responses; the disk was hidden and a soft chime played: 6 responses; the disk was visible and a soft chime played: 10 responses. A response meant that the fish swam toward the arch. The notes did not tell the students which fish noticed which cue or what each fish remembered.

The class planned a model with four parts. A cue outside the animal provides information. A sense organ receives that information. The brain processes the information and helps the animal select an action. The body then carries out the response. For example, the eyes may receive information from a visible object, while the ears may receive information from a sound.