Caminalcule activity
Goal: To introduce students to the concepts of holotype and paratype and
morphological taxonomic classification, both historically and with current methods.
Materials: Sheet illustrating 29 Caminalcules (‘extant’) from Sokal, R. R. (June
1983). "A phylogenetic analysis of the Caminalcules. I. The data base". Systematic
Zoology 32 (2): 159–184
Show the class the picture of a single caminalcule (Number 10). Some questions to
discuss:
How would you approach classification of a brand new organism?
What would you keep, and how would you mark it?
What would you do with that specimen?
How would others compare it?
Discuss holotypes and paratypes and how natural history museums use them
Split the class into groups of four. Hand out the sheet with all 29 caminalcules and
ask the groups to categorize them into ‘species’ (marking down the specimen
numbers in each species). Also ask them to identify the defining features of each
species – how do we tell them apart from one another?
What would differentiate one group from another?
Broadly, we need characters that don’t vary between groups
We care about shared derived traits, or synapomorphies
Will talk about reconstructing phylogenies later
On the chalkboard, expand the following table with as many groups and species as
needed.
Group Specie
s 1
(#’s)
Species 1
(features)
Questions for discussion:
Are there differences between groups for which specimens to include?
Differences in features chosen?
What were the challenges students faced when doing the classification?
