Lab: The Origin and Evolution of Animals
Lab Overview
Download and print the lab before you begin. Complete the required work on the printed pages, using the illustrations on this webpage as visual guides for the drawings and labels.
Your drawings do not need to match the illustrations exactly. Focus on the overall form and the important structures. Drawing requires you to actively identify shapes, relationships, and labels instead of simply looking at them, which helps you learn and remember the organisms more effectively.
Drawings are evaluated for completion, not artistic quality. The phylogeny exercises are evaluated for accuracy.
The phylogeny exercises require you to apply what you learn throughout the lab. Read the lab text carefully and use the organisms, structures, and evolutionary traits you encounter to determine where each characteristic belongs on the phylogenies. The completed phylogenies are not provided on this webpage.
Learning Goals
- Recognize major animal groups and the body features used to distinguish them.
- Connect animal body plans and developmental traits with evolutionary relationships.
- Use morphological characteristics as synapomorphies when interpreting an animal phylogeny.
Jump to Exercise
Exercise A: The Origin of Animals
Animals are multicellular opisthokonts, and choanoflagellates are their closest living relatives. In this exercise, you will compare single and colonial choanoflagellates and use a phylogeny to examine characteristics shared by major opisthokont groups.
Step 1. Draw a unicellular choanoflagellate.
Step 2. Draw a colony of choanoflagellates.
Step 3. Label the synapomorphies.
A synapomorphy is a shared characteristic that helps identify a branch of a phylogeny. Use the descriptions in your printed lab to compare Fungi, Choanozoa, and Animalia. For each branch, identify which group or groups descend from it, then choose the characteristic from the word bank that matches all of those descendants.
Fill all five boxes before checking your answers.