SYSTEMATIC BIOLOGY

LABORATORY 6: THE OTHER DEUTEROSTOMES, PARAZOA, AND RADIATA

Today's laboratory is your opportunity to observe representatives of the Deuterostomes other than the Craniates, Parazoans, and Radiata.  Please come to lab prepared to examine the assigned specimens and be ready to answer questions about them.  You may already have answered some of the questions in anticipation of the lab.

By the end of this laboratory experience, student teams will gain enough experience with deuterostomes other than the craniates, parazoans, and radiata to be able to:

DEUTEROSTOMATES

 

1.a.      Observe living sea urchins.  How do they attach themselves to the sides of the aquarium?

 

 

1.b.      Note the response when a glass rod taps one side of the animal.

 

 

1.c.      Describe the test of sea urchins and related animals.

Sea urchin oral surface

Sea urchin aboral surface

 

 

1.d.      Describe the structure of the sea urchin's mouth.

 

 

2.a.      Watch the brittle star move across the bottom of an aquarium.  Note the structural similarities between this animal and a sea star.

 

 

2.b.      How are they like sea urchins?

 

 

3.a.      Find a preserved crinoid.  Note its similarity to a sea star.  Describe the structure of the branches of the animal. 

3.b.      Now examine fossil crinoids and related taxa (blastoids, and cystoids).  Find segments of the stem, the calyx and the arms (or tentacles). 

 

 

3.c.      How did these animals procure their food?

 

 

4.         Describe the symmetry of the echinoderms.

 

 

5.a.      Note the Hemichordates on demonstration.  Find the gill slits, mouth, proboscis, collar, and trunk.  Look for the tentacles on the head.

Label the drawing of Balanoglossus in its burrow.

 

 

5.b.      Be sure to look at a Balanoglossus in a bioplastic mount (or whole mount slide).  Why are these animals called hemichordates?

 

 

5.c.      Find the fossils of possible hemichordates on demonstration.  Describe them.

 

 

6.a.      Examine a wm slide of Molgula.  Find mouth, gill slits, pharynx, siphons, digestive tract.  How do most adults feed? 

 

 

6.b.      Note the sea peach, a living urochordate.  How does it resemble a sponge?  How are they different from each other?

 

6.c.      Find a wm slide of an ascidian larva.  This is the larval form of a tunicate.  Locate the notochord in the animal's "tail".

7.a.      Look at a wm slide of amphioxus, Branchiostoma.  Find the mouth, pharynx, gill slits, digestive tract, fins, segmented myonemes, dorsal nerve cord, and notochord.

 

7.b.      Why is this animal called called a cephalochordate? 

 

 

7.c.      How do they feed?

 

 

7.d.      How is the animal like the larval ascidian?

PARAZOA

1.         Note the diversity of preserved, living, and fossil sponges.  What features do they all have in common?

 

 

2.a.      Look at the living Spongilla.  Describe the organism (color, texture, overall growth pattern, etc.).  Pay particular attention to the gemmules.  What is their function?

 

2.b.      Carefully slice off a very thin piece and examine it in a wet mount.  Find the choanocytes and spicules.  Describe them.

 

2.c.      Now remove the coverslip and add a drop of chlorox to the slice.  This should remove most of the organic material and leave just the spicules.  How many different types can you see?  Sketch them.

 

 

3.a.      Examine preserved synconoid sponge, Scypha (Grantia), on demonstration.  Note overall structure.  Find the ostia and osculum.

 

3.b.      Examine the sections of Scypha (Grantia).  Label the spongocoel, epidermis, flagellated chamber, mesenchyme, ostia, and incurrent canal.  Insert choanocytes, amoebocytes, and spicules into the illustration below.

3.b.      Indicate the direction of water flow in the drawing.

4.         Find examples of and be able to distinguish between members of the sponge classes.

RADIATA

1.         Look at the various living, preserved and fossil Radiates.  What conspicuous feature gives the group the name, Radiata?

 

2.a.      Examine living Hydra.  Describe the organism (color, texture, overall growth pattern, etc.).  Find the tentacles, mouth, body column, and the basal disk.

 

2.b.      Describe the behavior of the living animal.  How do they respond when brine shrimp nauplii are added to the culture?

2.c.      Look at a section of Hydra.  Find: gastrodermal cells, mesoglea, epidermis, gastrovascular cavity, nematocysts.  Add them to the illustration below.

 

                                                                                           100mm

 


3.a.      Investigate whole mount slides of Obelia.  Add gastrozoids, gonozoids, and medusa buds to the drawing below.

3.b.      Find a whole mount slide of the medusoid form of Obelia.  Sketch it below.

 

4.         Examine preserved Physalia and Velella.  Locate the crest, pneumatophore, gastrozoids, and fishing tentacles of both animals.

Physalia

 

5.         Cassiopeia is a jellyfish with some interesting attributes.  Watch the animal swim.  Describe it and its orientation.  How are the behavior and color related?

 

 

6.        Now observe the structure of preserved Aurelia.  Find the gonads, the mouth, radial canals, and the gastrovascular cavity.

 

7.a.      Metridium is a common sea anemone.  Examine the preserved individuals and find the pedal disk, tentacles, and mouth.

 

7.b.      Now look at a Metridium section slide.  Add and/or label septa, body wall, and gastrovascular cavity in the illustration below.

8.         Carefully examine a coral  like Astrangia.  What is the most conspicuous aspect of the stony structure that demonstrates its clear relationship with an animal like Metridium.

 

9.                  Similarly, consider the structures of brain coral (Meandrina), staghorn coral (Acropora), and organ pipe coral (Tubipora).

 

10.              Some corals are "soft".  Examine Gorgonia, and describe its overall growth habit (form).

 

11.              Now look at the varieties of fossil corals.  Which forms can be found alive today.  Which are not found among living corals today?

 

12.       Find preserved Ctenophores on demonstration.  How do they differ from cnidarians?

 

JRH & CAI:  Last revised: 01/27/2009