MAR111 Exercise 5
(10 points)
Name _________________________________
Lower Invertebrates - Porifera, Cnidaria, Ctenophora, Annelida
Porifera (Sponges)
1. Observe the whole dried sponge specimens. Notice the large number of pores and the
spongy texture that comes from the protein spongin. Now look at a slide of spongin using a
compound microscope. Describe what spongin looks like. ____________________________
____________________________________________________________________________
2. Below is a diagram of the anatomy of a simple sponge showing the spicules and 4 types of
cells (porocytes/pore cells, pinacocytes/epithelial cells, amoebocytes/wandering cells, and
choanocytes/collar cells). Use your book and/or your lecture notes to help you identify those 5
items on the diagram:
A = _________________________
B = _________________________
A
C = _________________________
E
D = _________________________
D
E = _________________________
B
C
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3. Use a compound microscope to look at the slide showing a whole mount of the sponge
Grantia. Draw what you see and label the pores, osculum opening, and spicules.
4. Look at the slide of loose sponge spicules using a compound microscope.
What are the two possible types (chemical compositions) of spicules?
____________________________________
___________________________________
What could you add to the spicules to determine which kind they are? (Hint: remember the
algae lab chemicals). __________________________________________________________
Draw the spicules you observed:
Cnidaria (Jellyfishes, Anemones, Corals)
There are 4 classes of cnidarians: Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa. You will see
examples of all except Cubozoa.
5. Use a compound microscope to look at the slide of the colonial hydrozoan Obelia. Draw the
organism and label the stem, polyps, and tentacles.
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6. Gonionemus is a hydrozoan jellyfish. Look at the preserved Gonionemus jellyfish, draw a
side view of it below, label the bell and tentacles, and show the oral and aboral sides.
7. Look at the plastic embedded specimen of Physalia (Portuguese man-of-war), which is a
colonial siphonophore, not a jellyfish. Using a jellyfish for comparison (Gonionemus or
Aurelia), name 2 ways that the Portuguese man-of-war is different from a jellyfish.
____________________________________
___________________________________
8. Corals and anemones are anthozoans. Hard corals have a polyp body shape like anemones,
but secrete a calcium carbonate skeleton. Look at some of the coral skeletons available. The
living coral animal used to live on top of that skeleton, with each polyp sitting inside a cup.
Solitary coral
Colonial star coral
Colonial brain coral
In living colonial corals, the polyps are interconnected by thin sheets of tissue called
coenosarcs. Inside the polyps, there is no stomach because cnidarians have no organs, but there
are digestive mesenterial filaments.
Most shallow, tropical corals have symbiotic photosynthetic microorganisms living inside their
tissues which provide additional nutrition and which remove wastes from the coral. What are
these microorganisms? ____________________________________
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Label the skeleton, tentacles, mesenterial filaments, mouth, and coenosarc on the diagram
below. Also show the oral and aboral sides.
9. View the slide of nematocyst stinging cells using a compound microscope. They will look
like this:
undischarged
discharged
What are two functions of the stinging cells of cnidarians?
____________________________________
___________________________________
Ctenophora (Comb Jellies)
10. Look at the preserved specimens of Pleurobrachia comb jellies using a dissecting
microscope to see better detail. Comb jellies get their name because they are gelatinous and
have 8 rows of ciliated combs that run along their bodies. They also have 2 tentacles, which
may not be present because they may have broken off during the capture and preservation of the
samples.
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Draw a comb jelly below and label a few representative rows of cilia combs.
11. Using a jellyfish for comparison (Gonionemus or Aurelia) and what you learned in lecture,
name 2 ways (other than the cilia combs) that comb jellies are different from jellyfish:
____________________________________
___________________________________
Annelida (Segmented Worms)
12. Look at the preserved Nereis worm using a dissecting microscope to see better detail. Note
the walking appendages which are called parapodia on each side of each segment. The ends of
the parapodia should have bristles (setae). These bristles are characteristic of the polychaetes
(meaning "many bristles") that are the dominant type of annelid worm in the oceans.
Draw the head and several segments of the worm. Identify the segments, parapodia, and
bristles/setae.
Summary
13. Each of the 4 phyla examined today represent a different body symmetry. Identify the
symmetry exhibited by each phylum. (Use your book and/or lecture notes.)
Porifera = ______________________
Cnidaria = _____________________
Ctenophora = ______________________
Annelida = ______________________
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