A Comparative Approach To Animal Dissections (A Phylogenic Study)

Lee VanNyhuis, Osakis High School, Osakis, MN. Lab report rubric was adapted from Tom Smith.
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Summary

In this biology inquiry lab, students study evolutionary relationships by making observations of preserved animal specimens, developing a question, then investigating by dissecting the specimens provided. This comparative approach offers an alternative to traditional dissections provided by most laboratory manuals. Along with studying evolutionary relationships, this approach could easily be adapted for comparative studies in anatomy and physiology.

Learning Goals

- Students will better understand phylogenic relationships based upon evidence.
- Students will develop and investigate a question they develop based on observations and prior knowledge.

Context for Use

I plan on using this activity as a study in evolutionary relationships in an advanced biology class offered to High School Juniors and Seniors. This activity could take from 2-4 class periods.

Description and Teaching Materials

Working groups of two or three, students are provided two or more preserved animal specimens, as well as equipment required for making observations and the actual dissection of the specimens. How many specimens and which type could be altered depending on the individual teacher's goals. In their groups students will make detailed observations of the preserved specimens. Observations could be written, drawings, pictures, etc. You may also want to provide students with live animals, pictures, stereo-microscopes, hand lenses or access to other informational sources to make observations from.

After making their initial observations, you may want to have the lab groups share their observations with the other groups. It may be beneficial then, to have the groups go back and make a second round of observations, allowing for observations that are more in depth. Encourage students to look for similarities, differences and patterns that are showing up. They should record their observations in a systematic way that may be decided upon by the individual student groups or by the instructor.
Following the observations. Students are to work in groups to develop a question that they can investigate during a dissection. The question should be focused on homologous structures, derived characteristics, phylogeny, evolution, etc. It may be useful to check each group's questions before they begin their investigation.

During the investigation students will dissect the specimens provided. The emphasis will be on comparing the different organisms, not necessarily on identification of specific body parts. To aid in dissection, I recommend providing dissection guides or reference material that will aide in data collection. Student data could include one or more of the following forms: drawings, diagrams, pictures, comparative tables, etc.

After students collect data from the dissections. They will be given time to digest and organize their data to determine trends, discuss their findings that relate to their questions, defend their findings based upon the data they collect, discuss problems that they encountered, and pose other questions that may have come up during their investigation. A formal or informal lab report could be required to use as a summative assessment. Assessment rubric in word format (Microsoft Word 34kB Aug31 08) Assessment rubric in pdf format (Acrobat (PDF) 25kB Aug31 08)

Teaching Notes and Tips

Students should have experience making detailed observations, developing questions from those observations, and designing investigations.

Safety considerations should be made when dissecting preserved specimens.

I am planning on using the following animals to concentrate on vertebrate phylogeny: Amphioxus, Lamprey, Dogfish Shark, Yellow Perch, and Necturus)

Assessment

For a summative assessment, I will have students produce a formal lab report that will be assessed by using a general lab report rubric. Informal formative assessments should be made while students make observations, and develop a question. Lab report rubric is attached.

Standards

9-12.I.B.1 - scientific investigation
9-12.IV.E.4 - evolution explains diversity

References and Resources