Download Kingdom Animalia: Phyla Porifera and Cnidaria

Kingdom Animalia: Phyla Porifera and Cnidaria
Essential Question(s): What are key characteristics to the animal kingdom?
Objectives:
1. Students will be able to distinguish essential characteristics in the animal kingdom.
2. Students will be able to differentiate between phyla of the animal kingdom
3. Student will recognize defining attributes in the Porifera and Cnidaria phylas.
In the following chart are the listed traits of animals and associated new vocabulary. Examine the
chart below and new vocabulary.
Kingdom Animalia
Cell
Feature
Body Plan
Nutrition
Life Cycle
Eukaryotic, no chloroplast present, small cells
Multicellular, Highly differentiated, Motile, Blastula, Gastrulation
Heterotrophic, may be predators or parasites.
Haploid (sperm and egg) and diploid(multicellular) phase
Introduction:
Animals originated in the oceans of the Precambrian era about 1.5 billion years ago. The first animals
were multicellular, eukaryotic and heterotrophic. They were the first “predators.” By the beginning
of the Cambrian period (543 mya), sponges and cnidarians were already present. During the end of
the Precambrian and the beginning of the Cambrian, a huge diversification of the animals took place.
This is called the Cambrian Explosion, although it spanned the Cambrian-Precambrian boundary
(565 to 525 mya). Most extant phyla are directly traced to this period. During this period, animal
phyla displayed dramatic variation in tissue formation, body symmetry, gut tube formation, major
feeding structures, molting strategies and skeletal arrangements. These evolutionary trends, through
natural selection, resulted in the major animal lineages of today. In this particular lab we will study
the first two phyla, Porifera and Cnidaria.
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Three essential characteristics to observe while progressing through each animal phyla are symmetry,
cephalization, and body cavity. There are two types of symmetry present in animals, bilateral like
humans, and radially symmetrical like a wheel.
As the exception, sponges do not exhibit any type of symmetry.
Cephalization, having a head, only occurs in bilaterally
symmetrical animals where the brain and most of its sensory
organs are located. Throughout this lab you will observe
acephalic organisms and one cephalic organism. Body cavity
refers to having an area where digestive and other internal
organs form and reside. Though Poriferans and Cnidarians do
Figure 1: Sea-anemone (cnidarian)
illustration showing radial symmetry
not have body cavities they will be included in the next animal
specimens to be observed.
Phylum Porifera
The basic body form of all sponges is a sac-like
structure consisting of three sections, outer-most
epidermal cells and aggregations of specialized
cells beneath them, such as flagellated cells called
choanocytes; and clusters of amoeboid cells that
form skeletal structures of various sorts. These cell
groupings are perforated by a large number of
small pores and canals. The main cavity of this
sac-like arrangement is called the spongocoel and
has at least one large opening to the outside, called
an osculum. The sponges are taxonomically
classified based on the type of skeletal elements
produced.
Figure 2: Sea Sponge labeled diagram.
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These include calcareous spicules, siliceous spicules, or proteinaceous spongin fibers. This leads to
the basic sponge taxonomy, which includes three classes.
Sponges in the Class Calcarea have calcium carbonate spicules, which have three or four rays. All of
these sponges are marine. The Class Hexactinellida have siliceous spicules, which are 6 rayed. These
sponges are all marine and most often cylindrical in form and found in deep water. The Class
Demospongiae are typically called “bath sponges” because they are used by humans for bathing. These
sponges have spongin fibers, or siliceous spicules, or both. They represent over 90% of the sponges in
the world, and one family is found in fresh water.
In all sponge types, the body is designed to facilitate filter-feeding. Water is pulled into the pores and
canals by the beating of the flagella of choanocytes. The water moves into the spongocoel and is
eventually forced out through the osculum. As the water passes across the choanocytes, food
particles (microscopic algae, bacteria, and organic debris) adhere to the cells and are eventually taken
into food vacuoles for intracellular digestion.
Figure 3: 1=Porifera body structure. Colour-coding: *Yellow: pinacocytes *Red: choanocytes *Grey: mesohyl * Pale
blue: water flow Structure types: *Left: asconoid *Middle: syconoid *Right: leuconoid Re
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Figure 4: Scanning electron micrograph images of a selection of microscleres and megascleres of demosponges, not to scale, sizes vary
between 0.01 and 1 mm.
Observe:
1) Obtain a preserved specimen of Grantia, look closely and try to see how their bodies are designed
to move water in order to feed and move water.
a. Are any of the features observed in Grantia those of an animal? Explain.
2) Examine a slide of a Grantia cross-section. Pay close
attention to the folded body wall.
a. Draw your observation indicating the external environment and the
Spongocoel.
b. Label choanocytes and amoebocytes from your previous drawing.
Figure 5: Grantia cross section
Figure 6: Spongin fibers
(left)
Figure 7: Isolated Spicules
(right)
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3. Examine a prepared slide of sponge fibers. These are the commercial sponges.
Cnidaria:
Members of the largely marine Phylum Cnidaria are considered to be more "advanced" than the
poriferans for two major reasons. First, they are the first animal to show multicellular layers, i.e.
tissue level organization, although they have no organs. Second, the adult forms are derived from
two distinct embryonic germ layers, the ectoderm and the endoderm hence, they are diploblastic.
Higher phyla are triploblastic (derived from three distinct embryonic germ layers). The organisms in
the phylum Cnidaria are characterized by radial symmetry. Terms for direction use the mouth as a
point of reference. The end of the organism which contains the mouth is oral; the opposite end of the
animal is aboral. Radial symmetry refers to the fact that any plane passing through the oral-aboral
axis divides the animal into two equal halves, or that the body tends to radiate out from the oralaboral axis like spokes of a wheel.
The basic body plan of the cnidarians is a sac-like structure, with a gastrovascular cavity. The
gastrovascular cavity has a single opening which serves as both mouth and anus; it is often
surrounded by tentacles. The body wall has an external cell layer, the epidermis; an internal cell
layer, the gastrodermis that lines the gastrovascular cavity; and a jelly-like layer between these two,
called the mesoglea which may be either cellular, or more often, acellular. Unique cellular
components, called nematocysts are found in cells called cnidocytes. Cnidocytes (hence the phylum
name Cnidaria) are especially abundant on tentacles, but may be generally distributed throughout
the epidermis and gastrodermis.
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Figure 8. Diagram of a cross section of a jellyfish (Olindias formosa) showing the main parts of a jellyfish
The life cycle of a typical cnidarian alternates between an often sessile polyp stage and a freeswimming medusa stage. The existence of two distinct forms such as this is known as developmental
polymorphism. Both stages exhibit the radial body plan described above; however, the polyp stage is
cylindrical and attached at the aboral end to a substrate, while the medusa stage is flattened or
domed in appearance with the mouth oriented downward. In Scyphozoans the polyp is an asexual
stage, while the medusa is a sexual stage. In some Cnidarian classes, either the polyp or the medusa
stage may be reduced or completely absent (e.g. Hydra). You will examine the three classes of the
Phylum Cnidaria: Class Hydrozoa, Class Scyphozoa, and Class Anthozoa.
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Summary characteristics of class Hydrozoa and specific specimens.
Class Hydrozoa
*Dominant Polyp
stage *Germ layers
are separated by
acellular mesoglea
*Ectodermal cells
have cnidocytes and
muscular contractile
cells *Endodermal
cells secrete
enzymes for
digestion
Specimen 1 :
Hydra
*Small * lives
in shallow
freshwater
*Prey on
smaller
invertebrates
*Do not have
medusa stage
Specime 2:
Obelia
Specimen 3:
Physalia
Specimen 4:
Ganoneimus
*Has colonial
polyps
*Polymorphic
polyps
*Gastroid
polyps are for
feeding
*Gonozoid
polyps are for
reproduction.
*Floating
polymorphic
colony of polyps
*Gas filled polyps
for floatation
*Nutritive polyps
make up long
tentacles
*Tentacles are
lethal for small
fish
*Large
medusae
*Gonads
attach to
radial canals
and appear
similar in
males and
females
*Tentacles
have a rough
surface
Figure 9: Hydra budding 4X
Observe:
1) Obtain a live Hydra sample. Allow a few minutes for specimen to relax in petri dish and then
observe under a dissecting microscope.
2) Tap the edge of petri dish and observe behavior of Hydra. Place live Daphnia near Hydra tentacles.
a. Describe your observations.
b. What tissues must exist for the behaviors observed?
3) Examine prepared slides of budding hydras and a cross section of hydra showing
endoderm and ectoderm.
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Figure 10: Obelia 4X
Figure11: Obelia Medusae 40X
Figure 12: Physalia Tentacle
3) Under a microscope examine prepared slide of both polyp and medusae of Obelia.
Differentiate a feeding polyp from a reproductive polyp.
4) Examine preserved sample of Gonionemus,
Class Scyphozoa
Commonly called the jellies are the Aurelia and Cassiopeia. The planula is the
typical larva of a cnidarian. After sexual reproduction, this larva is formed; it
swims to a new location and develops into a polyp or medusa. The gelatinous
medusa is the dominant body form in the life cycle of Schyphozoans.
Class Anthozoa: Corals
Figure 13: Jelly cc10
Corals are colonial cnidarians, often having huge numbers of polyps. They
have internal skeletons, which you see here. You should be able to see the small holes where the polyps
lived. When the coral was alive, the entire skeleton was covered by a skin of living tissue. These corals
made their living mostly by symbiosis with photosynthetic zooxanthellae, a type of dinoflagellate
(Protista)
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Observe:
1) Examine anthozoans on display.
a. How does the feeding method of a sponge compare with that of a coral?
Introduction to the Flatworms:
Phylum Platyhelminthes Flatworms. The acoelomates
are animals that lack a coelom. Acoelomates lack a
body cavity, and instead the space between the body
wall and the digestive tract is filled with muscle fibers
and loose tissue called parenchyma. These animals
possess three living cell layers (i.e.: ectoderm,
mesoderm, and endoderm) which makes them
triploblastic. The Platyhelminthes, or flatworms are
an economically important group because they
include the parasitic tapeworms and flukes, which
Figure 14: Coral Polyp anatomy
affect both humans and the livestock we depend on.
These acoelomates are advanced over other radiate animals in several ways. 1. Their bilateral
symmetry adapts them for direct movement. 2. Their tissues are well defined and organized into
complex organs. 3. The nervous system is organized and concentrated in the anterior end of the
animal (cephalization). 4. They do not depend on simple diffusion for elimination of nitrogenous
wastes, but have an
excretory system based on
structures called flame
cells.5. They possess a
complex digestive tract
with both a mouth and
anus.
Figure 15: Planaria Body plan
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Class Turbellaria (Planarians)
Planarians are found on the underside of stones and submerged leaves or sticks in freshwater springs
and ponds. They are often confused with leeches, which they resemble in size, shape and color.
Unlike leeches planarians are not segmented and usually do not resort to blood meals.
Slides of stained Turbellaria
(Planaria)
View slides of stained whole mount of
planaria. Sketch and label the digestive
system in your preparation.
Figure 16: Planaria digestive tract 4X
Observation of live Planarians
Gently, using forceps, an eyedropper or a finger, place a live planarian in a petri dish with the
spring water provided. Periodically replace the water as it evaporates.
External Structures:
Observe the animal and decide which is the anterior, posterior, dorsal and ventral surface.
On your live specimen note the ear-like auricles. These structures bear sensory cells but they are
tactile neither auditory nor olfactory. Note the eyes, do they possess lenses?
Locomotion:
Note how your specimen moves across the petri dish. This gliding movement is accomplished in part
by mucus on which the planarian moves via cilia. The body is also propelled by waves of muscle
contractions. Note how the animal will shorten and lengthen its body length to accomplish
movement.
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Reactions to Stimuli:
Observe the responses of planarians to touch (thigmotaxis) and light (phototaxis) through the
following experiments: - Response to touch. Very gently touch the outer edges of the worm with a
probe or pencil. Which parts of the body are the most sensitive? - Response to directional
illumination. Direct a strong light at the planarians from one side of the dish and observe their
movements. Periodically, move the dish around the light pausing to note the animal's response. Is the
response random or directional?
Class Trematoda (Flukes)
All trematodes are parasitic, harbored in or on a
great variety of animals. Many have two
intermediate hosts before reaching the final host.
Examine a slide of Schisistosom
jamonicum. An odd feature of this genus is
the strong sexual dimorphism. The males are
stouter than the females and have a longitudinal
groove called the gynecophoric canal. Even odder,
the thinner female normally resides there,
permanently embraced by the male. Note the
strong oral sucker and secondary sucker near the
Figure 17. A fluke showing internal
anatomy.
anterior end.
Class Cestoda (Tapeworms)
Tapeworms are all endoparasitic and
show extreme adaptations to their
existence through the complete loss
of their digestive tract, and a focus
Figure 18. An adult tapeworm.
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on reproduction. Most require a single intermediate host and a final host, where the adult tapeworm
resides. As their name implies their long bodies are usually made of segments called proglottids. As
new proglottids are formed anteriorly the older ones are pushed towards the tail, hence the most
mature proglottids are found at the posterior end. The scolex is located on the head and is used for
attachment.
Examine the preserved slides of Taenia pisiformis. Attempt several sketches of the scolex
and suckers, which are used for attachment. Sketch both mature and immature proglottids if present.
Label the structures you can discern.
Since tapeworms are hermaphroditic each proglottid contains both male and female gonads. The
mature proglottid contains a genital pore laterally (on the side). From this pore two tubes extend into
the interior. The anterior, convoluted tube, which branches in the middle of the proglottid, is the
sperm duct. It branches to the different testes in the segments. The posterior duct is the vagina, which
connects to the ovaries via the oviducts.
Planarian Regeneration Experiment:
As we learned in class planarians have incredible powers of regeneration. It's now time to make some
cuts! Now pair up with another classmate.
1. Clean razor blade or sharp scalpel
2. A clean petri dish with cover and partially filled with spring water
3. Obtain two flatworms per group
Procedure:

Using a pair of forceps, place the planarian on a piece of tissue paper and place both on a cube
of ice. The planarian will immediately extend and become catatonic.
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
Place the ice, tissue paper, and planarian under a dissecting microscope and decide how you
want to cut your worms. If you decide to make longitudinal cuts make sure the cut is clean
and has completely separated the cut surfaces.

Place the cuts and cut planarians into the petri dish (with your name on the cover) and place in
a cool place. To insure the health of our specimens the water must be changed every 3 days
with fresh spring water. At each water change remove any dead pieces which will appear
fuzzy and gray.

Use the attached tables on the following page to sketch your initial cuts. At each water change
(every 3 days) examine and sketch the regeneration of new body parts.

Observe the specimens for 1 week.

Important: If you make longitudinal cuts for 2 headed worms, you will need to renew the cuts
1 and 2 days after the initial incisions. This is done to prevent the two pieces fusing back
together.
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Sources:
1. De Anza Lab Manualhttp://faculty.deanza.edu/heyerbruce/bio6a
2. Survey of the Animal Kingdom : Phyla Porifera, and Cnidaria
3. http://cfcc.edu/blogs/jrogers/files/2014/09/Phylum-Platyhelminthes.pdf
Image Sources:
Figure 1 - Sea anemone
Figure 2: Sea Sponge labeled diagram.
https://commons.wikimedia.org/wiki/File:Sea_sponge_diagram.svg#/media/File:Sea_sponge_diagra
m.svg
Figure 3: https://commons.wikimedia.org/wiki/File:Porifera_body_structures_01.png
Figure 4: Scanning electron micrograph images of a selection of microscleres and megascleres of
demosponges, not to scale, sizes vary between 0.01 and 1 mm.
https://upload.wikimedia.org/wikipedia/commons/b/ba/Demospongiae_spicule_diversity.png
Figure 8:
https://commons.wikimedia.org/wiki/File:Cross_section_jellyfish_en.svg?fastcci_from=24861
Diagram of a cross section of a jellyfish (Olindias formosa) showing the main parts of a jellyfish
Figure 13: : "Jelly cc10". Licensed under CC BY-SA 2.0 via Wikimedia Commons https://commons.wikimedia.org/wiki/File:Jelly_cc10.jpg#/media/File:Jelly_cc10.jpg
Figure 14: http://oceanservice.noaa.gov/education/tutorial_corals/media/supp_coral01a.html
Figure 17: http://www.phsource.us/PH/PARA/Chapter_6.htm
Fugure 18: http://pathologyoutlines.com/topic/parasitologydipylidiumcaninum.html
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