Lab 5: Nemertea, Bryozoa, Brachiopoda, Rotifera 2 March 2016 Today we have several very distinct spiralian clades to look at. Nemertea Cerebratulus marginatus preserved in ethanol from the MCZ. Observe it submerged under the dissecting scope. Draw and label according to your knowledge of nemerteans; use a textbook if necessary to guide your observations. Remember the video of the huge nemerteans feeding on a dead seal in Antarctica! We will find some colorful and smaller nemerteans in Bocas del Toro (see the guide of Bocas Invertebrates!). Lab 5 – Nemertea, Bryozoa, Brachiopoda, Rotifera OEB 51 Bryozoa Bugula neritina (live!) and Bugula stolonifera (in ethanol) CHOOSE ONE This erect, branching colonial form demonstrates polymorphism in bryozoans. Under a dissecting scope, identify feeding zooids and avicularia (only in B. stolonifera), drawing and labeling any recognizable structures (especially the lophophore!). What is the function of avicularia? And of the lophophore? Schizoporella unicornis Observe this colony of encrusting bryozoans. Draw a part of it representing the individual zooids, lophophore (what is it for?) and any other structures you can see. 2 Lab 5 – Nemertea, Bryozoa, Brachiopoda, Rotifera OEB 51 Brachiopoda Lingula sp. (lingulid – preserved in ethanol) and Laqueus sp. (shells) Observe and draw both of these preserved brachiopods. Point to the orientation of the animal and main external structures. Lingulid brachiopods have changed very little since the Ordovician period. • How can you tell if you are looking at a brachiopod or a bivalve? Describe some of the differences between the external morphology and shell of the two groups. 3 Lab 8: Rotifera, Nematoda, Nematomorpha OEB 51 Rotifera Today we have representatives of the major groups of rotifers: live monogononts and bdelloids, and preserved acanthocephalans. Start by choosing one of the live forms to study the anatomy in more details (and indicate which species you chose). Make wet mounts and take special care to observe their jaw apparatus (mastax) at high magnification. Can you see the wheel organ moving? Why is this a trick question? • Brachionus, marine monogonont • Philodina, a freshwater bdelloid Which sex are you observing? And why might this also be a trick question? 4 Lab 8: Rotifera, Nematoda, Nematomorpha OEB 51 • Echinorhynchus, an acanthocephalan (preserved from the MCZ) Examine under a dissecting scope. Make a rough sketch of the animal and try to identify as much of the anatomy as you can (use the textbooks as guides). What size are these, roughly? How does it compare to the free-living rotifers you just observed above? What are some characters that unite these parasitic animals with other rotifers? 5 .