Biol 212 Zoology
Lab 02: Phylum Porifera (10 points)
Introduction
The most primitive and ancient group of the kingdom
Animalia is the phylum Porifera. They have no true tissues
and generally no symmetry. They are basically composed
of two layers of uncoordinated cells, the outer layer of
flattened cells called the pinacoderm and an inner layer of
flagellated feeding cells called choanocytes making up the
choanoderm. The choanocytes line an internal cavity, the
spongocoel. The flagella of the choanoytes beat, setting up
currents of water that enter the spongocoel through small
pores called ostia; the choanocytes filter food from the
water current, then send the filtered water out through a
large exit pore, the osculum. Between the pinacoderm and
choanoderm is a space called the mesohyl. In the mesohyl
are amoebocytes, which transport nutrients about the body
of the sponge; amoebocytes also have limited and
generalized immune function, removing foreign particles
from the sponge. Also in the mesohyl are the unique
skeletal elements of the sponges, spicules. Besides
providing skeletal support, spicules help us group sponges
into three classes, as we’ll later see. Simple sponges, such
as Leucosolenia, have a single spongocoel and single
osculum; complex sponges are essentially simple sponges
that have fused together with interconnecting spongocoels
and numerous oscula. Sponges are mostly marine and are
benthic and sessile, being attached either to hard substrates
or hard objects in the water.
Evolutionarily, we think these simplest of animals
probably evolved from choanoflagellates, which evolved
from primitive fungi.
The purpose of this lab is to acquaint you with the
three classes making up the phylum Porifera.
Fig. 2.1: Cross section of a simple
sponge. 1 = osculum, 2 =
choanoderm, 3 = spongocoel, 4 =
pinacoderm, 5 = ostia, 8 =
amoebocytes in hesohyl, 9 =
spicules
For the Lab Report:
*On the upper, right-hand corner of your lab report, print your name, Biol 212, Lab 2: Phylum
Porifera, and the date you did this lab.
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Introductory Obujectives
Objective 1: Define the following terms: Pinacoderm, choanoderm, choanocytes, spongocoel,
ostia, osculum, mesohyl, amoebocytes, spicules. Identify these structures on any representative
of the three sponge classes using either specimens or photographs.
Objective 2: Describe the flow of water through a simple sponge.
For the Lab Report:
Write out these questions then answer them:
1. Write out then define the following terms: Pinacoderm, choanoderm, choanocytes,
spongocoel, ostia, osculum, mesohyl, amoebocytes, spicules.
2. Describe the flow of water through a simple sponge.
Exercise 2.1: Class Calcarea
Introduction
Members of the class Calcarea, the calcareous sponges, are completely marine, and are
found attached to hard substrates from the rocky intertidal into the deep sea. They have spicules
in the mesohyl made of calcium carbonate that are usually three rayed, which separates them
from the other classes of poriferans.
Objectives
Objective 3: State the habitat of the class Calcarea.
Objective 4: State the chemical composition and morphology of the calcarean spicules.
Objective 5: Identify the phylum and class of typical representatives of the class Calcarea from
specimens, photographs and/or microscope slides of skeletal elements.
Objective 6: Identify and label the ostia and oscula of typical representatives of the class
Calcarea in specimens or photographs.
Materials and Methods
*Preserved specimens of Leucosolenia, Scypha, Grantia or other simple Calcarea for dissecton
*Microscope slide of Grantia c.s., Leucosolenia c.s. or Scypha c.s.
*Microscope slide of Grantia or other Calcarea spicules
-Compound microscopes, slides & coverslips, lens paper, immersion oil, lens cleaning solution
-Dissecting microscopes
-Needle probes, forceps
-Single-edged razor blades (or scalpels) for dissecting sponges
-Dropper bottle containing sodium hypochlorite (Chlorox) for spicule preparation
-Watch glasses
*Preserved or dried specimens of various Calcarea for examination, not dissection
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1. Place a single specimen of Leucosolenia, Sypha or Grantia in a watch glass and cover with
water. Place the preparation under a dissecting microscope. Draw the external anatomy of the
sponge, identify and label the structures as indicated in the For the Lab Report box below.
For the Lab Report:
3. Write out, “3. Phylum Porifera, class Calcarea, Leucosolenia external anatomy.” If
Leucolenia was not used, write down the genus that was. Draw the external anatomy of the
specimen. Identify and label the ostia and osculum. Include an accurate size rule next to your
drawing—use a millimeter ruler to measure your specimen and make your size rule. No
credit for drawings without accurate size rules. To the right of yur drawing, state how big the
size rule is in millimeters (for example, “Size rule = ___ mm.” Also, include any notes that
might help you to identify the organism on the lab practical! Have your instructor check and
initial your drawings for credit; all drawings must be completed in lab and signed by your
instructor for credit!
For the Lab Report:
Write out these questions then answer them:
4. What is the habitat of the class Calcarea?
2. Obtain a clean microscope slide. Using a single-edged razor blade or scalpel, cut off a 2 to 3
mm square section of your sponge specimen and place it on the slide. Add a few drops of
sodium hypochlorite solution. Caution! DO NOT get sodium hypochlorite on your skin or in
your eyes. If you do, IMMEDIATELY go to the eyewash station, flood your eye with water
and call your instructor! The sodium hypochlorite will dissolve the soft tissue of the sponge
so you can examine the spicules. Continue with the next section then come back to this in a
few minutes.
3. Obtain a commercially-prepared microscope slide of Grantia c.s. (cross section) or other
available Calcaria genus. Start with lowest power, and work your way up to 1000x. Identify,
draw and label pinacocytes, mesohyl and choanocytes as per the instructions in the For the
Lab Report box below. IF no commercially-prepared slide is available, get another
microscope slide and coverslip. Using a single-edged razor blade or scalpel, make a thin
section of the body wall from the pinacoderm through the mesohyl to the choanoderm and
place it on a microscope slide. Add a drop of water and a drop of methylene blue stain. After
a minute, pour off the excess methylene blue stain and add another drop of water. Gently
place the coverslip over the specimen and push down a little with a pencil eraser to squash
the preparation. Examine under a compound microscope as indicated in the For the Lab
Report box.
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For the Lab Report:
5. Write out, “5. Phylum Porifera, class Calcarea, Leucosolenia cross section.” If Leucolenia
was not used, write down the genus that was. Identify, draw and label pinacocytes, mesohyl,
spicules (if apparent) and choanocytes. Note that the specimen may have been prepared with
acid to dissolve the spicules, so you may not be able to see the spicules. Include an accurate
size rule next to your drawing. No credit for drawings without accurate size rules. To the
right of your drawing, include total magnification (for example, “400x”) and how big the size
rule is (for example, “Size rule = ___ m.” Also, include any notes that might help you to
identify the organism on the lab practical! Have your instructor check and initial your
drawings for credit; all drawings must be completed in lab and signed by your instructor for
credit!
4. Place several drops of water on the spicule preparation from #2 and imbibe off the excess
fluid with a small corner of paper towel so as to wash the excess sodium hypochlorite form
the preparation. Examine under a compound microscope without a coverslip. Draw two or
three representative spicules as per the instructions in the For the Lab Report box below.
For the Lab Report:
6. Write out, “6. Phylum Porifera, class Calcarea, Leucosolenia spicules.” If Leucolenia was not
used, write down the genus that was. Identify, draw and label two or three spicules. Include
an accurate size rule next to your drawing. No credit for drawings without accurate size rules.
To the right of your drawing, include total magnification (for example, “400x”) and how big
the size rule is (for example, “Size rule = ___ m.” Also, include any notes that might help
you to identify the organism on the lab practical! Have your instructor check and initial your
drawings for credit; all drawings must be completed in lab and signed by your instructor for
credit!
5. Examine a commercially-prepared slide or demo slide of Calcareaq spicules. If these spicules
are different from your preparation, sketch a couple under the For the Lab Report #7.
For the Lab Report:
7. Write out, “7. Phylum Porifera, class Calcarea, spicules.” Identify, draw and label two or
three spicules. If a commercially-prepared slide or demo slide is not available, simply enter
“N/A after #7 in your lab report. Include an accurate size rule next to your drawing. No credit
for drawings without accurate size rules. To the right of your drawing, include total
magnification (for example, “400x”) and how big the size rule is (for example, “Size rule =
___ m.” Also, include any notes that might help you to identify the organism on the lab
practical! Have your instructor check and initial your drawings for credit; all drawings must
be completed in lab and signed by your instructor for credit!
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For the Lab Report:
Write out these questions then answer them:
8. What is the chemical composition and morphology of calcarean spicules?
Exercise 2.2: Class Hexactinellida
Introduction
The class Hexactinellida, the glass sponges, have delicate spicules in the mesohyl made
of silicon dioxide (glass) that are usually six-rayed, often with one very long, pointed and sharp
ray. These sponges are entirely marine. Although some hexactinellids occur attached under rocks
in the rocky intertidal, most of these sponges are deep-sea.
Objectives
Objective 7: State the habitat of the class Hexactinellida
Objective 8: State the chemical composition and morphology of hexactinellid spicules.
Objective 9: Identify the phylum and class of typical representatives of the class Hexactinellida
from specimens, photographs and/or microscope slides of skeletal elements.
Materials and Methods
*Preserved or dried representatives of the class Hexactinellida (for demo, not dissection) such as
Euplectellum aspergillum (Venus’ flower basket)
*Commercially-prepared slide showing Hexactinellida spicules
1. Because they are so fragile, you should not handle the dried representatives of the class
Hexactinellida, the glass sponges. Identify and draw a representative of this class and make
necessary notes that would allow you to identify it on a lab practical as per the instructions in
the For the Lab Report box below.
For the Lab Report:
9. Write out, “9. Phylum Porifera, class Hexactinellida.” Identify and draw a representative of
this class. Use a centimeter ruler to measure the specimen and include an accurate size rule
next to your drawing. No credit for drawings without accurate size rules. To the right of your
drawing, state how big the size rule is in centimeters (for example, “Size rule = ___ cm.”
Also, include any notes that might help you to identify the organism on the lab practical!
Have your instructor check and initial your drawings for credit; all drawings must be
completed in lab and signed by your instructor for credit!
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2. If one is available, examine a commercially-prepared slide or a demo slide showing
Hexactinellida spicules. Draw a few representative spicules as per the instructions in the For
the Lab Report box below.
For the Lab Report:
10. Write out, “10. Phylum Porifera, class Hexactinellida, spicules.” Identify, draw and label two
or three spicules. If a commercially-prepared slide or demo slide is not available, simply
enter “N/A after #7 in your lab report. Include an accurate size rule next to your drawing. No
credit for drawings without accurate size rules. To the right of your drawing, include total
magnification (for example, “400x”) and how big the size rule is (for example, “Size rule =
___ m.” Also, include any notes that might help you to identify the organism on the lab
practical! Have your instructor check and initial your drawings for credit; all drawings must
be completed in lab and signed by your instructor for credit!
For the Lab Report:
Write out these questions then answer them:
11. What is the habitat of the class Hexactinellida?
12. What is the chemical composition and morphology of hexactinellid spicules?
Exercise 2.3: Class Demospongiae
Introduction
Members of the class Demospongia, the bath sponges and others, are mostly marine; a
few live in freshwater attached to submerged tree branches. Although some demospongians have
spicules made of silicon dioxide, the fact that they are not six-rayed separates them from the
hexactinellids; further, most demospongians have spicules made of a soft, interwoven protein
matrix called spongin. Spongin is what gives natural bath sponges their sponginess!
Objectives
Objective 10: State the habitat of the class Demospongia.
Objective 11: State the chemical composition and morphology of demospongin spicules.
Objective 12: Identify the phylum and class of typical representatives of the class Demospongia
from specimens, photographs and/or microscope slides of skeletal elements.
Objective 13: Identify and label the ostia and oscula of typical representatives of the class
Demospongia in specimens or photographs.
Materials and Methods
*Preserved or dried representatives of the class Demospongiae (for demo, not dissection)
*Commercially-prepared slide showing Demospongiae spicules/spongin
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1. You may handle the representatives of the class Demospongiae. Identify and draw a
representative of this class and make necessary notes that would allow you to identify it on a
lab practical.
For the Lab Report:
13. Write out, “13. Phylum Porifera, class Demospongia.” Identify and draw a representative of
this class. Identify and label the ostia and oscula. Use a centimeter ruler to measure the
specimen and include an accurate size rule next to your drawing. No credit for drawings
without accurate size rules. To the right of your drawing, state how big the size rule is in
centimeters (for example, “Size rule = ___ cm.” Also, include any notes that might help you
to identify the organism on the lab practical! Have your instructor check and initial your
drawings for credit; all drawings must be completed in lab and signed by your instructor for
credit!
2. Gently squeeze a dried demospongin skeleton. Record your observations in the For the Lab
Report box below.
For the Lab Report:
Write out these questions then answer them:
14. Observation of squeezing a demospongin skeleton. Was the skeleton hard, brittle or resilient?
3. Obtain a commercially-prepared slide showing spongin, or if one is not available, look at the
demo slide prepared by your instructor. Draw a few strands of spongin as per the instructions
in the For the Lab Report box below.
For the Lab Report:
15. Write out, “15. Phylum Porifera, class Demospongia, spongin.” Identify, draw and label a
few of the spongin fibers. Include an accurate size rule next to your drawing. No credit for
drawings without accurate size rules. To the right of your drawing, include total
magnification (for example, “400x”) and how big the size rule is (for example, “Size rule =
___ m.” Also, include any notes that might help you to identify the organism on the lab
practical! Have your instructor check and initial your drawings for credit; all drawings must
be completed in lab and signed by your instructor for credit!
For the Lab Report:
Write out these questions then answer them:
16. What is the chemical composition and morphology of spongin?
17. What is the habitat of the class Demospongia?
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For the Lab Report:
Write out these questions then answer them:
18. What might be the advantage to the Calcarea and Hexactinellida of having hard spicules?
19. What might be an advantage to the Demospongia of having a soft, “spongy” skeleton?
20. What are the definitive (unique) characteristics of the phylum Porifera?
21. What are the definitive characteristics of the class Calcarea, class Hexactinellida and class
Demospongiae?
~When you’re finished, help clean up!
1. Is your lab bench clean and wiped down with antiseptic solution?
2. Are all materials returned to their proper place?
3. Is the oil immersion objective of your microscope clean?
4. Is the lowest-power objective of your microscope positioned down?
5. Is the power cord draped loosely about one of the oculars?
6. Is your microscope put away?
7. Is all refuse disposed of properly?
8. Is the lab generally in order?
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