This activity is a follow up to Activity 1. Here students do the next step in the experiments to determine of the effects of toxicants on blackworms, investigating the effects of nicotine. As a follow up to the activity, the students then ‘think of the next experiment’.
Estimated Time of Activity
2 class periods (1.5- 2 hours)
Students will be able to do the following as a result of the activity:
- Continue to develop concept mapping, team work, safe animal handling, data recording, and critical thinking skills.
- Understand the concept of dose-response and the definition of toxicology as well as its connections to other sciences, the real world, and their own lives.
- Learn how to conduct a toxicological assay.
Students should have completed Activity 1.
- Form the students into groups of 3 to 5 depending on class size and collect the materials needed for the Blackworm lab.
- Students should briefly examine the blackworms and first distinguish the anterior end from the posterior end. The anterior is blunter and more darkly pigmented than the posterior. The anterior is also the end that will move first. If several worms are in the chamber, they will clump together in a ball, as they like to “cling” to things. This is a normal behavior that the students will want to note. Students can separate the group by gently probing the worms or pipetting with water.
- Once the anterior and posterior ends are established, students should briefly observe the worms’ swimming behavior. Touch the probe to the posterior end. The worm will swim forward in a corkscrew fashion, alternating clockwise and counterclockwise. When the worm is probed on the anterior end, it will coil and reverse its position.
- Next, direct students to briefly observe crawling behavior. The worm can be placed in a Petri dish or weighing dish on moistened filter paper (with all excess water removed). Again they should probe both the posterior and anterior ends of the worm. In each case the worm will move by peristaltic crawling (successive waves of muscle contractions) in the opposite direction.
- Have students record their observations in the data sheet provided in the Blackworm lab packet.
- Introduce the activity on pages 10-11 of the Blackworm packet and continue the lab as time permits.
- For homework, ask students to design an experiment or study that follows up on the experiment. They should cartoon the follow-up study’s procedure for in- class discussion.
- On Day 2 of the Activity students should form groups.
- Instruct students to discuss in groups what makes a ‘good’ research proposal. They should then make a list of 5-10 ‘criteria’ by which research proposals will be evaluated.
- Have groups exchange their cartooned proposals, evaluate them using the criteria they have selected, and make a decision as a group about which proposal to approve.
- Groups should report to the class their selection and criteria.
Observe student participation with the group and class discussion.
Review student responses to Data sheets, cartooned research proposals, and group criteria for project selection.
The students should complete the observation data sheet in class as a group in Day 1. Students should individually cartoon research proposals for homework after Day 1. Students should complete a list of criteria and review research proposals on Day 2.
- Blackworm lab packet
- California Blackworms (available at aquarium/ pet stores where live fish food is sold)
- Nicotine dilutions
- Graduated cylinders
- Four Petri dishes (top and bottom) per group
- Filter paper
- Probes (rubber bands, electrical tape, stir sticks)
- Beral pipettes
- Spring water
- Black permanent markers
- You will need to purchase California blackworms prior to class. These can usually be found at aquarium stores. Be sure to have adequate copies of the lab instructions from the Blackworm lab packet for the class (pages 10-11), and prepare the nicotine concentrations according to the instructions provided in the Blackworm lab packet (pages 3-4). It will save time if the instructor assembles the probes as well (page 4).
- For more information on the ‘Think of the Next Experiment’ portion of this activity, instructor should refer to pg. 1384 in the article “Selective Use of the Primary Literature Transforms the Classroom Into a Virtual Laboratory” by Sally Hoskins et al; and pg. 11 of the tutorial on the CREATE method.
Web Links for blackworms – good, facts, pictures, and lessons for future editing.
Biology facts about Blackworms: http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Lvfacts.htm
Professor C. D. Drewes’ website (http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/) has a wealth of information on all types of invertebrates, animations, and biology facts. It also has numerous articles published by Professor Drewes and many links to interesting biology sites. It’s worth the time to explore.
TOXICANTS AND CALIFORNIA BLACKWORMS: http://coep.pharmacy.arizona.edu/curriculum/blackworms/pdf/orig_bwrm.pdf
Toxicity Testing with California Blackworms: Alcohol http://www.niehs.nih.gov/health/assets/docs_p_z/blackworms-alcohol.pdf