 |
| A radial phylogenetic tree of life (version of the tree found in Life: the Science of Biology [9th edition] by Sadava, Hillis, Heller, and Berenbaum) |
_______________________________________________
PHYLOGENETICS
In this lab students learned how to approach classifying the diversity of invertebrate animals based on evolutionary relationships rather than in overall morphological similarity. The main approach to do so was by examining the most basic concepts of phylogenetics by using cladistics as a tool.
They did a small exercise in which a character data matrix was completed, by observing a variety of specimens of several invertebrate phyla, and used to generate a cladogram. By doing so, some of the difficulties that systematists have to face became obvious, and students attempted to solve them with a variety of approaches.
Thursday, January 26, 2012
PROTOZOA AND PORIFERA
 |
| Amoeba proteus, a protozoan |
 |
| Spicules from a sponge |
___________________________________________
Preserved specimens from the main groups of protozoans were observed under the microscope for students to identify their main morphological features:
Ciliates: Spirostomum, Vorticella, Didinium, Stentor, Paramecium
Flagellates: Trichonympha, Euglena, Volvox, Trypanosoma, Ceratium
Ameobeoids: Amoeba, Foraminifera, Radiolaria, Actinosphaerium
Preserved specimens of the various classes of the phylum Porifera (click here for more sponges) were displayed for students to observe their general morphology. Some specimens ere available to be treated with commercial bleach to dissolve the organic matter and observe the spicules of different individuals. By using polarizing filters students were able to determine if the spicules were calcareous or siliceous.
Observed specimens belonged to the classes:
See the filtering activity of sponges
-----------------------
No comments:
Post a Comment