snail

Observation of Snail Behavior

Name _______________________________________ Period ___

Background The purpose of this lab is to use the scientific method in studying snail behavior. We will be observing the snail’s response to various stimuli, and collecting our observations. We will then interpret those results by explaining why these responses would be useful to the snail for surviving in its natural environment.

The natural environment of a snail involves humidity. The snails prefer cool, moist, and dark environments during the day and they feed during the night.

Snail Anatomy

DO NOT DO ANYTHING THAT MIGHT HARM OR INJURE YOUR SNAIL!!!

Procedure Pre Observations Record your snails behavior, movement and behavior in the fish tank before you begin the experiment.

Snail Behavior Locomotion (a) Place an active snail in a clear bowl and while holding the bowl above your head, observe how the snail moves. Record your observations. The snail leaves behind a trail of mucus – why is this mucus useful to the snail?

(b) Turn the bowl over and place the snail on the bottom of the bowl. Allow the snail to move freely over the surface of the bowl. How does the snail respond to the edge of the bowl? Record your observations.

(c) Rate of locomotion: You will measure the rate of locomotion of the snail in millimeters traveled per minute on three different surfaces. For each surface make three trials and average the rate of movement for each surface. Record your observations in a table. The three surfaces are: table top, paper, ¼ inch of water in bowl. Convert all units to cm/min SNAIL SPEED Trial 1 Trial 2 Trial 3

Table Top

Paper

¼ inch of water

After you’ve gathered your speed data- explain your reasons behind the snail’s speeds?

Movement in response to chemicals (chemotaxis) The snail has 2 pairs of tentacles which it uses to sample its surroundings. (a) Crush some lettuce and place a thin streak of its juice across a clean, dry table top. Place the snail on the table so its direction of movement is toward the juice. Record your observations of the snail’s response.

(b) Dampen a cotton swab with water and bring it close to the tentacles. Record your observations.

(This is a control – testing the snail’s response to the damp cotton swab). a. Dampen a cotton swab with vinegar and test the snail’s response. Record your observations.

b. Repeat, but this time dampen your cotton swab with amyl alcohol and record your observations.

Movement in response to light (phototaxis) Place the snail on a dry, clean surface and dim the lights in the room. Shine the light from the dissecting microscope on the snail so it has its choice to travel on an illuminated or a darkened surface. Record your observations.

Summarizing your data: Write a summary of your 3 experiments? Include answers to the following questions in your Conclusion.

Locomotion: What is the response of the snail’s locomotion to different surfaces?

Movement in response to gravity: Does the snail exhibit a positive (towards) or negative (away from) response to gravity?

Movement in response to chemicals: Does the snail like lettuce, water, vinegar, amyl alcohol?

Movement in response to light: What is the snail’s response to light?

Analyzing your data: You will interpret your data by answering the following questions: How does the snail’s behavior help it survive in its environment? Remember your answer must be supported by your observations. Use your observations from each of the lab – locomotion, movement in response to gravity, chemical, light and your observations of the snail in its natural environment to back up your answer to the question.