lab practical 1 (1)

8/4/2019 Lab Practical 1 (1)

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Kingdom Protozoa

Introduction

1. Protozoa are unicellular

2. Microscopic in size

3. Live as single individuals or simple colonies

4. Body contains numerous organelles which carry various vital functions and which are analogous

to the organs and organ systems found in higher animals

5. Most scientists believe that multicellular animals (metazoa) evolved from a group(s) of

protozoans (possibly the flagellates)

6. They were considered the simplest group and most primitive phylum IN the animal kingdom

7. For some time, TAXONOMISTS believed that Protozoa were more closely related to the

unicellular aglae (than to metazoans) and were in the Kingdom Protista (with the unicellular

algae)

8. Recent evidence suggests that the differences are significant and they are in separate kingdoms:

Kingdom Protozoa

9. Found in many different kinds of moist or wet habitats: fresh, marine, and brackish water: in

moist soil, sewage, in some spp of animals, in or on some plants

Classification- Kingdom Protozoa

Amoeboid Protozoans

1. Phylum Amoebozoa

a. Includes amoebas

b.

Could me naked or shelled c. Most use pseudopodia locomoation

d. Examples: Amoeba proteus, Arcella and Diffugia (testate amoebae); and Entamoeba

histolytica (a human parasite)

2. Phylum Foraminifera

a. Mostly marine, benthic organisms

b. Have Calcium Carbonate test

c. Multichambered test

d. THIN, BRANCHED pseudopodia= reticulopoidia- projects out openings in the test

3. Phylum Radiozoa

a. Mostly PHYTOPLANKTONIC organisms b. Such as: radiolarians and acantharians

c. Have specialized pseudopodia= axopodia- that is long and thin with systems of

supporting microtubules

d. Endoskeleton of: Silica (radiolarians) and Strontium Sulfate (acantharians)

The Flagellated Protozoans



1. Phylum Euglenozoa

a. Contains photosynthetic euglena and other parasitic forms

b. Es: Leishmania and Trypanosoma (causes sleeping sickness)

2. Phylum Metamonada

a. Contains the parasite GIARDIA as well as other forms

3. Phylum Dinozoa

a. Contains Dinoflagellates

b. Important members of phytoplankton, cause of “so-called” red tides, and some are

endosymbionts for hard coral (cnidarians)

4. Phylum Choanozoa

a. Contains choanoflagellates

Ciliated Protozoans

1. Phylum Ciliophora (ciliata)

a. Protozoa with cilia or ciliary organelles in at least one stage of their life cycle

b. Usually have 2 types of nuclei: macronucleus and micronucleus

c. Examples: Paramecium, Tetrahymena, Vorticella, Stentor, Blepharisma, and Trichodina

Spore Forming Protozoans

1. Phylum Apicomplexa

a. Have apical complex during one stage: a unique structure at the anterior end that allows

them to attach and enter their host cell

b. They reproduce by formation of spores; but spores lack polar filaments

c. All are parasitic

d. Have no differentiated locomotory organelles e. Some have complex life cycles containing both sexual and asexual stages

f. Examples: Plasmodium vivax- parasite that causes malaria in humans

g. Eimeria (can cause coccidiosis in various animals)

LAB EXERCISES

Amoeboid Protozoans

1. Phylum Aboebozoa

a. Amoeba proteus- good example of organization of animal cell

b. More than a cell, because it functions as a complete organism c. When preparing wet mount: the amoeba were slightly heavier than their solution so

were at the bottom

d. Study under low power and with reduced illumination to the minimum

e. The living specimens are nearly transparent and almost invisible in bright light

f. Constantly changes shape; (lack permanent orientation of body)

g. Have pseudopodia= “false feet” (temporary extensions of a cells)



h. ID:

i. Endoplasm- inner granular region, the bulk of the cytoplasm

ii. Clear cytoplasm that is around the endoderm

iii. Cell membrane- outer membrane around the amoeba (also called the

plasmalemma or the plasma membrane)

iv. Nucleus- doesn’t have a fixed position; biconcave disc shaped with some folds

or wrinkles (when stained, dark material in the nucleus)

v. Contractile vacuole: clear vacuole used to rid excess water; in the endoplasm

and collects excess water from cytoplasm and secretes it out of the cell

1. After it secretes it’s contents, a new vacuole is formed WHERE?

2. Was thought to have helped with excretion of waste products from

protein metabolism

3. Found to just help in maintaining water balance (osmoregulation)

vi. Food vacuole- a vacuole that contains food materials and digestive enzymes

that break down the food materials into soluble materials that can be utilized by

the amoeba

1. HOW ARE THEY FORMED? HOW ARE THE UNDIGESTED CONTENTS OF

A FOOD VACUOLE DISPOSED OF AFTER DIGESTION HAS TAKEN PLACE?

i. Amoeboid Movement

i. Closely related to cytoplasmic streaming (found in all living cells)

ii. The pseudopodia are used for support, feeding, and locomotion

iii. Movement accomplished by movement of relatively liquid plasmasol

iv. The plasmasol moves from the center, toward and into the expanding

pseudopodia

v. When it reaches the periphery of the pseudopodia, the plasmasol changes into

plasmagel.

vi. Thus, the plasmasol moves the pseudopodia forward and the plasmagel FIXES it

into position

vii. Not yet determined how, but involves contractile proteins like actin and myosin

that are used in the contraction of muscles

viii. The plasmasol changes between the relatively fluid plasmasol to the gel-like

plasmagel

ix. Locate the movement of the granules in the pseudopodia

j. Reproduction

i. Use asexual binary fission

ii. Binary fission- the nucleus and cytoplasm of the parent cell divide into 2

daughter cells that are about equal in size

iii. The daughter cells are genetically identical to the parent cell- unless there was

an occurrence of a mutation in one of the daughter cells

k. Other Amoebozoa

i. Others are more specialized



ii. Some live in shells or tests (formed or secreted from sand grains or other

materials)

iii. Some are parasitic or symbionts in digestive tracts of various animals

iv. Entamoeba histolytica- an important parasite of humans, causes amoebic

dysentery- a disease spread by drinking water or eating raw vegetables that

were contaminated by human wastes

2. Phylum Foraminifera

a. Marine SARCODINAS that form tests of CaCO3 (calcium carbonate) (multichambered

tests)

b. Mostly found on sea bottom (benthic)

c. Contribute to formation of chalk and limestons

i. Ex: the White Cliffs of Dover in England, Bedford’s limestone found in Indiana

and Illinois, and some was used to build the Egyptian pyramids

d. Important to petroleum geologists

i. Believe that in ancient environmental conditions they were favorable to the

formation of petroleum

e. Long, branched pseudopodia called reticulopodia that they project out of holes in the

test

3. Phylum Radiozoa

a. Planktonic organisms

b. Radiolarians = Silica endoskeletons

c. Acantharians= strontium sulfate endoskeletons

d. Specialized pseudopodia- AXOPODIA- long and thin containing a system of supporting

microtubules

DIFFERENCE BETWEEN RADIOZOA AND FORAMINIFERA

Flagellated Protozoans

1. Phylum Euglenozoa

a. Euglena= common phytoflagellate found in greenish surface scum of standing/slow

moving water

b. Sensitive to light- change intensity and they tend to moveaway

c. They normally remain stationary in bright light d. Borderline between the plant and animal kingdoms

e. Have chloroplasts- thus are autotrophic;

i. Organic materials are SYNTHESIZED by inorganic materials absorbed from the

medium

ii. Energy is provided from light from the sun

f. Actively swimming because of large flagellum



g. Euglenoid movement (metaboly)- worm-like movement, with waves of contractions

moving along the body: due to the elasticity of the thick outer cover- pellicle

h. Their chloroplasts and their storage of plant-like starch shows their close relationship

with plants

i. ID:

i. Chloroplasts with green chlorophyll

ii. Nucleus

iii. Flagella

iv. Contractile vacuole

v. Red stigma (eye spot)

Volvox

a. Common green algae, not member of the Kingdom Protozoa

b. Spherical green volvox are large enough see swimming without a microscope

c. Chloroplast make the spherical volvox green, thus they are autotropic

d. Once thought of as colonial but now they think more like multicellular individuals

e. Their cell coordination and cellular respiration is greater than in most other colonial algae and

protozoans

f. OCCURS IN GREAT #S IN FRESHWATER PONDS AND LAKES

g. Supports the theory that multicellular animals may have evolved from a group(s) of protozoans

h. Illustrates the organization of a simple colonial (or multicellular) organism

i. Have a nucleus, red stigma (light sensitive), two flagellum, a green chloroplast, and a contractile

vacuole

j. The two flagellum project/beat outward from the surface

k.

Their beating keeps the spheroids in a CONSTANT SPINNING MOTION l. Some adjacent cells are connected by cytoplasmic bridges or strands

m. in spheroid, should observe 1 or more large reproductive cells or gonidia

n. reproduction can be sexual or asexual (in asexual the embryos are from the gonidia)

o. 0.5 mm in diameter (very small) with green cells embedded in their outer wall

Other Euglenozoa

1. Trypanosoma- thin, undulating membrane connecting its long whiplike flagellum with its body

a. Several spp cause sleeping sickness and other diseases in humans

2. Leishmania

Other flagellated protozoans

Important flagellates include:

(1) The dinoflagellates

(2) Symbiotic flagelaltes that inhabit the digestive tracts of termites and

wood roaches



(3) Choanoflagellates- some peculiar flagellates that may be related to

sponges

(4) Several important parasites of humans

[A] Dinoflagellates

found in both fresh and marine waters

freshwater dinoflagellates can cause an unpleasant odor or taste in human water

supplies

marine dinoflagellates (Gonyaulax and Gymnodininium) are often associated with red

tides [in coastal waters (N.A., Asia, or Europe)] that sometimes leads to massive fish kills

many spp form characteristic outer covering of cellulose

increase numbers of Pfiesteria have resulted in fish kills and human health problems

some non-motile MARINE dinoflagellates live symbiotically within the GASTRODERMIS

OF CNIDARIANS

they non-motile marine dinoflagellates are important for reef building corals= called

ZOOXANTHELLAE

ZOOXANTHELLAE- a marine dinoflagellate that lives as an endosymbiont in the

gastrodermis of cnidarians (important to reef building corals)

[B] Flagellates that live as symbionts in the digestive tract of termites and wood roaches

Experiments have shown that termites lack the digestive enzyme (cellulase) needed to

digest the cellulose in the wood they eat

The flagellates make these enzyme products from the cellulose breakdown available for

the nutrition of the flagellates and the host

Termites that had the flagellates removed died soon after, no matter how much wood

they ingested

the flagellate benefits from both the continuous supply of cellulose and the suitable

anaerobic environment of the host hindgut

mutualism is occurring- both the termite and the flagellates benefit

Ciliated Protozoans

1. Phylum Ciliophora

a. Paramecium is a large common, ciliated protozoan

i. Often found in water containing bacteria and decaying organic matter

ii. Several spp with different structures and details (120-300 microns in length)

iii. Used Paramecium multimicronecleatum in the lab

iv. Methyl cellulose is a viscous material and serves to slow the swimming of the

fast moving paramecium ( so you can see it’s internal organelles)

v. In other words, the methyl cellulose is a viscous material that is added to slow

the swimming of the fast moving paramecium so you can see it’s internal

organelles

vi. Move with cilia



vii. Slipper-shaped body with an oral groove beginning at the anterior end and

running diagonally across the anterior portion of the body

viii. NOTE THE FORM, COLOR, AND BEHAVIOR OF THE ANIMALS IN PREPARATION

ix. at the end of the oral groove is the cytosome or the “cell mouth”

1. food particles are passed through as a result of the action of the

specialized oral cilia lining the oral groove

x. paramecium is much more advanced in STRUCTURE than amoeba

1. Id:

a. Cilia- numerous, cylindrical protoplasmic extension (cylindrical

extensions of the cytoplasm) that cover the surface of the

Paramecium; function in LOCOMOATION and FOOD GATHERING

b. Pellicle-thick outer covering of the body through which cilia

project. (complex structure, but details hard to observe)

c. Macronucleus- the large nucleus located toward the center of

the cell

i. Controls the metabolic function

ii. Transparent in living animals-best studied in stained

preparation

d. Micronucleus- smaller nucleus located close to and lying partly

within a depression on the oral side of the macronucleus

i. Involved mainly with the reproductive and hereditary

functions of the animals

ii. Best studied in a prepared slide

Having two distinct types of nuclei is called NUCLEAR DIMORPHISM and is found only in

the Phylum Ciliophora.

Some have only one micronucleus (Paramecium caudatum) and others have 2 or more

micronuclei

e. Contractile vacuole- 2 clear, slow pulsating vesicles near each

end of the body; each is surrounded by several radiating canals

that collect water from the surrounding cytoplasm

i. They are not fixed in position; they move

ii. They move alternately

iii. Functions to collect and discharge excess water

iv. Marine protozoans usually have these

v. Freshwater usually lack these

vi. WHY? Because they have to eliminate waste and may

get a rush of water into it???

f. Food vacuole-are located in the cytoplasm



i. Undigested materials are discharged through the

CYTOPYGE, or anal pore, located posterior to the oral

groove

ii. Forms from the cytopharynx

g. Specimen undergoing fission- look in lab book

h. Specimen undergoing conjugation- look in lab book

b. Feeding

i. Filter-feeding organisms

ii. Normally feeds on bacteria and yeast cells collected by specialized food-

collecting apparatus

iii. Oral groove extends diagonally back along the body to a funnel-shaped

cytopharynx

iv. Food is swept along the mouth by specialized oral cilia lining the groove

v. It is passed through the circular cytosome “cell mouth” at the opening of the

cytopharynx

vi. Then is passed through the cytopharynx into the newly formed food vacuole

Cilia and Flagella

1- most of the surface of the Paramecium is covered by thin, hair-like projections called cilia

(singular: cilium)

2- cilia are extensions from the cortical (outer) cytoplasm of the cell and play an important role in

feeding and locomotion

3- cilia are closely related to the flagella (singular: flagellum) [found on the surface of other kinds

of protozoans]

4-

they have minor structural differences 5- if the projections are short and numerous= cilia

6- long and few = flagella

7- relatively simple back and forth movement (cilia)

8- Flagella (more complex)- may involve a series of helical waves propagated along the flagellum

9- Have common basic structure

10- Cross section- has an outer membrane enclosing 9 pairs of microtubules and 2 single

microtubules in the center of the cilium or flagellum

11- They microtubules have dynein arms that project from them and cause the microtubules to slide

past one another causing the cilia or flagellum to move

12- Basic pattern in all cilia and flagella ( ex: trachea lining of verts, tail in spermatozoa, mollusk gills) 13- Involve contractile proteins similar to those found in striated muscle

Reproduction

1) Paramecium reproduces by a simple type of asexual reproduction termed TRANSVERSE FISSION

2) Details of fission are best studied in stained microscopic slides

3) The micronucleus first divides by mitosis



4) No visible chromosomes are formed in the macronucleus

5) The macronucleus simply constricts and the two portions separate

6) Macronuclear division is followed by cytoplasmic division (cytokinesis)

7) The process of fission may be repeated rapidly and under optimal conditions

8) Paramecium can reproduce asexually two or more times a day

Unlike Amoeba, Paramecium...

1- can also reproduce sexually!

a. Conjugation – where 2 individuals come together

i. 2 individuals come together

ii. Adhere by their oral surfaces

iii. Undergo a complex series of changes in both the macronuclei and the

micronuclei

iv. Exchange a single pair of micronuclei (one from each cell)

v. Separate

vi. And resume asexual reproduction

vii. After the exchange of micronuclei in each paramecium, the newly introduced

micronucleus fuses with another (nonmigrating)micronucleus

viii. Thus, there is an exchange of hereditary material and a subsequent fusion of

hereditary material from the two parents, analogous to the situation in ordinary

sexual reproduction

Spore Forming Protozoans

Phylum Apicomplexa

1- All members are parasitic on other organisms

2- Many spp are parasitic on inverts like earthworms, crabs, and oysters

3- Others are parasites of verts, including humans

4- A few most important: Plasmodium (causes various forms of malaria in humans) and Eimeria

5- Malaria is one of the most serious parasitic diseases of humans (occurs in many parts of the

world)

6- Modern drugs and improved saitation measures have brought some forms of the disease under

control, but other serious forms still remain

7- These parasites are mostly intracellular and difficult to find and identify in and intro lab like this

one

Phylum Porifera

1- Includes sponges

2- Were once thought to be plants

3- Very primitive body organization



4- Porous body permeated by a stream of water canals through which water is pumped by the

action of special flagellated cells (choanocytes)

5- Consists of loose aggregation of cells embedded in a jellylike matrix

6- No distinct tissue layers except for an epithelial layer of pinacocytes

7- Choanocytes serve to create water currents through the internal canal systems and filter out

tiny food particles from the water

8- All digestion is INTRACELLULAR (within individual cells)

9- Think represent early offshoot from the main line of animal evolution and not to be closely

related to more advanced animals

10- Were thought to be of economic importance

11- Sponge fishing were big

12- Overfishing and sponge disease took their role and the importance is not as great

Do the id for the phylum porifera

1. Osculum

2. Spongocoel

3. Choanocytes

4. Pinacoderm

5. Ostia

6. Spicules

7. amoebocyte

Phylum Cnidaria

1) formerly called coelenterates

2) simplest animals with DEFINITE TISSUES 3) 2 well-defined tissue layers with a gelatinous material= mesoglea in between the two

4) Epidermis covers the external surface of the body(from the ectoderm) and the gastrodermis

from the endoderm (covers a single internal body cavity)

5) Hey are diploblastic or two-layered animals

6) Phylum cnidaria and the related to phylum Ctenophora are known for their RADIAL SYMMETRY

7) So these two are often called the RADIATE PHYLA

8) ASKED IF I NEEDED TO KNOW ABOUT THE PHYLA AND WHERE THEY CAME FROM

9) Two basic body forms:

a. Polyp stage- attached

b. Medusa stage- free-swimming

10) Some spp exhibit both a polyp stage and a medusa stage and their lifecycles involve an

alternation of these two body forms or “generations”

11) Distinguishing characteristics:

a. Tentacles- around the mouth

b. Diffuse nerve net- provides a modest degree of nervous coordination



*The name Cnidaria is based on the special cnidoblast cells- that produce the nematocysts or stinging

capsules

*the Ceolentarata is based off of the gastrovascular cavity – coelenterons

*Phylum Ctenophora –derives name meaning “comb-bearer” from characteristic eight rows of comb

plates or ctenes (used for locomotion)

Classification

The phylum Cnidaria is divided into 3 classes

1. Class Hydrozoa(Hydroids and Siphonophores)

a. Usually with both polyp and medusa in the lifecycle

b. Medusa with velum, gonads on radical canals of medusa

c. Freshwater and marine spp

d. Polyp is generally the dominant stage

e. Ex: Obelia, Hydra, Gonionemus, and Physalia (Portuguese Man-O-War)

2. Class Scyphozoa (True Jellyfish)

a. Mainly large marine jellyfish

b. With abundant Mesoglea

c. Polyp stage (pcyphistoma) reduced or absent

d. No velum in medusa

e. ALL MARINE

f. Ex: Aurelia, Chryaora (sea nettle) and Cyanea

3. Class Anthozoa (Sea Anemones and Coral)

a. Solitary or colonial animals with polyp stage only

b. Medusa absent

c. Pharynx or gullet present

d. Gastrovascular cavity partitioned by septa

e. All marine

f. Ex: metridium (sea anemone), astrangia (coral), Gorgonia (sea fan), and REnilla (sea

pansy)

Laboratory Exercises

Class Hydrozoa (hydroids and siphonophors)

1. A polyp: Hydra

a. Generally polyp form of a Cnidarian

b. Live in freshwater streams, lakes, ponds

i. Usually attaches to submerged sticks, stones, or vegetation



ii. Feeds on various small aquatic animals

c. About 14% of hydra live in freshwater streams, lakes, or ponds where they are attached

to submerged sticks, stones, or vegetation and feed on various small aquatic animals

d. General appearance and morphology

i. Pond water not tap water (cuz tap water has sopper that is toxic to hydra)

ii. ID:

1. Basal disc- lower end that serves for attachment

2. Hypostome- elevation between the bases of the radially arranged

tentacles

3. Tentacles- at the free end in a circle (how many?- we had 6)

4. Mouth-in the center of the hypostome

5. Buds- products of asexual reproduction

6. Cnidoblasts - swellings on the tentacles (produce nematocysts)

7. Nematocysts – stinging capsule, often armed by spines or barbs; can

contain toxins, enzymes or other chemicals in its capsule

8. Gastrovascular cavity

9. Epidermis- covers the external body surface

10. Gastrodermis- covers a single body cavity

11. Mesoglea (latter 2 can also be ID’d in cross section)- gelatinous material

between the epidermis and the gastrodermis

e. Behavior

i. The hydra changes shape

ii. When touch one of the tentacles it seemed to move away but Brit speara said

that hers clasped onto it

iii. It uses amoeboid movement when it is attached (polyp stage)

iv. But when it is free moving, (medusa stage) it moves like a slinky, so that it can

reattach to different places by the basal disc

f. Feeding Behavior

i. It is CARNIVORE and feeds on living crustaceans, rotifers, insect larvae and other

small animals

ii. HOW LONG DID IT TAKE?

iii. It paralyzes it’s prey by sticking the nematocysts in them, then engulfs them into

the mouth

iv. Has an incomplete gut at this stage

v. Hydras feeding reaction is normally caused by bodily fluid oozing from the body

of it’s prey (feeding reaction can also be elicited by a solution of a tripeptide,

reduced glutathione)

vi. Cnidoblasts and Nematocysts

1. Cnidoblasts- appear as swellings on the tentacles

2. Each cnidoblast is a cell containing a nematocyst, or stinging capsule

3. So a nematocyst is a stinging capsule



4. Cnidoblasts can be stained to help observations (add 0.01% metylene

blue solution to edge of coverslip)

vii. Nematocysts

1. Hydra has 4 different types of nematocysts: each have a distinctive

structure and function

2. Important in:

a. Capture of food

b. Locomotion

c. In attachment

3. Nematocysts are complex organelles that formed within a developing

cnidoblasts

4. Each consists of :

a. An outer protein capsule

b. Long, coiled tube often armed with spines or barbs

c. Also contains toxins, enzymes, and other chemicals in the

nematocysts capsule

d. When stimulated coiled tube is shot out and they empty their

contents (barbs or spines, toxins, enzymes, other chemicals)

viii. Reproduction

1. Asexually by budding

2. Sexually by production of eggs and sperm

3. Most are dioecious (sexes separate)

4. Some are monoecious (both sexes in one individual)

5. Males are often more common than females in the lab setting (not

sure why)

6. On female specimens

a. Ovary may bear an unfertilized ovum, or later stage of

development

b. Since early embryonic development may occur while the

embryo is still attached to the parent

ix. Histological structure

1. Diploblastic (two-layered) structure of its members

2. ID:

a. Epidermis- outer, thinner, epithelial layer of cells

b. Gastrodermis- inner layer of cells that covers a single body

cavity

c. Mesoglea- very thin, noncellular layer between the epidermis

and the gastrodermis

d. Gastrovascular cavity- internal cavity lined by the gastrodermis

x. Cellular Structure

1. More advanced that Volvox colony

a. General structure



b. Degree of differentiation of cellular structure and functions

c. Cellular specialization in the form of reproductive, sensory,

secretory and primitive nerve cells

d. Nerve cells are located among the cells of the epidermis

e. Nerve cells have two or more processes connecting with:

i. Sensory cells

ii. Contractile fibers of epithelial cells

iii. Other nerve cells

f. Nervous impulses are spread in a radiating pattern from the site

of initiation

g. This type of diffuse nerve net with no nerve centers (ganglia) or

brain is characteristic of Cnidarians

So they have a diffuse nerve net with no nerve centers (ganglion) or brain

Remember that all cnidarians have a diffuse nerve net and tentacles

(Phylum Cnidaria)

Class Hydrozoa

A colonial polyp: Obelia

1. A colonial MARINE animal

2. Illustrates complex life cycle with ALTERNATING polyp and medusa stages

3. Exhibit polymorphism or morphological specialization of its members (like other colonial

animals)

4. So…can distinguish two different kinds of individuals in an Obelia colony

a. Feeding polyp (hydranth)

b. Reproductive polyps (gonangia)

5. The feeding polyp- the hydranth- consists of tentacles with armed nematocysts, mouth,

hypostome, and a delicate outer cover, the hydrotheca (extension of the perisarc)

6. Gonangia (reproductive polyps) consist of a CENTRAL BLASTOSTYLE, on which medusa buds

develop, and a thin outer covering, the gonotheca

7. At the distal end of the gonotheca there is an opening , the GONOPORE

8. Newly liberated Medusa escape through the GONOPORE

9. HAVE NO TENTACLES OR MOUTH, HOW DO THEY RECEIVE THEIR NUTRITION??

a. 10. Hydranths and gonangia are attached to a main stem, or hydrocaulus

11. The hydrocaulus (main stem) consists of a cylindrical tube of living tissue, the coenosarcs, and

an outer secreted covering, the perisarc

12. in a cross section, the coensarc resembles a cross section of Hydra with an outer epidermis, an

inner gastrodermis, and a thin intervening layer of mesoglea

13. LIFE CYCLE OF OBELIA LOOK AT IT!



a. Parent secretes egg and then sperm fertilizes it

b. Turns into zygote

c. Blastula

d. Planula

e. Young colony

14. Do not need to know why the CAMPANULARIA IS DIFFERENT

15. The obelia life cycle illustrates the alternation of generations characteristic of the phylum

cnidaria( which means the back and forth stages of the polyp and medusa stages)

16. Metagenesis is the alternation of the asexual polyp generation and the sexual medusa

generation

17. The alternation generations of Cnidarians are different that the alternating generations of plants

18. In cnidarians, the polyp and medusa generations are diploid (2N) and the alternations between

plants is between a haploid (1N) gametophyte genereation and a diploid (2N) sporophyte

genereation

19. Life cycle of obelia:

a. The polyp generation produces medusa buds within its gonangia

b. Tiny, short-lived medusa escape into the plankton and produce either eggs or sperm

c. Fertilized eggs develop into ciliated planula larvae

d. Planula larvae swim about in the sea for a time

e. Settle to transform into a new polyp

f. Buds transformed by asexual reproduction of polyp do not detach

g. So they form a colony

Phylum Cnidaria

Class Schyphozoa (true jellyfish) – A Schyphozoan Jellyfish: Aurelia

1. Aurelia- common, marine jellyfish

2. Large specimens (up to 12 inches) in diameter

3. Polyp form- scyphistoma

4. Scyphistoma (polyp form) is small and sessile, and lives attached to rocks and other submerged

objects in shallow coastal waters

5. STUDY STAINED PLASTIC MOUNTED SPECIMENT OF Aurelia !!!

6. Observe the 4 part radial symmetry

7. Locate 4 long arms arising from the corners of the square mouth

8. Along the arms: find short oral tentacles that help capture food

9. The food is then moved toward the mouth along the ciliated groove on the oral side of each arm

10. After passing through the mouth the food enters the gastrovascular cavity

11. Internally the gastrovascular cavity is divided into four gastric pouches

12. A ring of gastric filament within each gastric pouch immobilizes or kills any food organisms still

active

13. The gastric filaments bear many cnidocytes

14. Four horse-shaped gonads surround the ring of gastric filaments within the four gastric pouches



15. Four horse-shaped gonads SURROUND THE RING OF GASTRIC FILAMENTS WITHIN THE FOUR

GASTRIC POUCHES

16. observe the complex branching systems of the radial canals that distribute food materials from

the gastric pockets to the other parts of the bell, and an outer circular canal around the margin

of the bell

17. around the margin of the bell, locate the 8 marginal sense organs

18. these marginal sense organs, 8 that are around the margin of the bell, are sensitive to touch and

balance

19. Reproduction and Life cycle:

a. Mature Aurelia medusa release gametes from the gonads into the gastrovascular cavity.

b. The gametes exit from the mouth

c. Fertilization is external

d. Fertilized eggs or zygotes develop into ciliated planula larvae

i. May be retained for a time on the oral arms of the medusa and later settle to

the sea bottom

ii. There the larvae develop into a small trumpet-shaped polyp (scyphistoma)

e. Under appropriate conditions the scyphistoma forms and releases a series of free-

swimming saucer-shaped ephyra larvae

f. These ephyra larvae bear marginal sense organs and other medusoid features

Class Anthozoa- A Sea Anemone: Metridium

1. Typically sessile; mainly marine; attach to rocks, shells, pilings, and other hard substrates in the

sea

2. Only found in polyp form

3.

No medusa generation in this class 4. Polyp form is the highest degree of specialization in the cnidarians polyps is the metridium

5. North atlantic anemone: metridium

6. Has a mouth in the middle of tentacles and a basal disc at the bottom to attach to things

because sessile and marine

7. Mouth is at the center of the oral discs

8. Can be dissected horizontally or longitudinally

9. Tubular gullet leading internally from the mouth to the large gastrovascular cavity

10. One or more ciliated grooves (siphonoglyphs) should be found along the edge of the gullet

11. Usually the cilia within these grooves beat inward to provide a respiratory current of water into

the gastrovascular cavity 12. Remaining cilia usually beat outward to remove wastes and foreign particles from the

gastrovascular cavity

13. When feeding the beat of cilia along the gullet wall is reeersed and aids in moveing food

particles into the gastrovascular cavity

14. Gastrovascular cavity is partially divided into sections by thin vertical walls of tissue called septa



15. Some septa attach to the central gullet (primary septa) other extend only partway into the

gastrovascular cavity (secondary or teriary septa) and bear thickened septal filaments on their

free inner margins

16. Septal filaments that etend below the partial septa as thin,twisted, threads , the acontia are

used to quiet living pretty taken into the gastrovascular cavity

Reproduction and Life Cycle:

Both sexual and asexual

a) Some anemones reproduce by longitudinal fission

b) But main asexual means of reproduction in Metridium is PEDAL LACERTAION

c) PEDAL LACERATION (the main means of asexual reproduction in Metridium) this is where bits

of tissue from the pedal disc are split from the anemone as the animal moves along the

substrate

d) These tissue pieces later regenerate an entire small anemone, literally in the footsteps of its

parent

e) Sexual reproduction- OCCURS SEASONALLY WHEN GAMETES ARE RELEASED FRO THE GONADS

ON THE PARTIAL SEPTA into the gastrovascualr cavity

f) The gametes are released and are fertilized in the sea

g) The fertilized eggs develop into free-swimming planula larvae

h) After a period as planktonic larvae, the planulae settle on tsome hard substrate and

metamorphose into an anemone

i) Sexual occurs seasonally when the gametes are secreted from the gonads in the paritial septa

into the gastrovascular cavity and then released in to the sea to become fertilized which then

are planula larvae (after a time of being planktonic larvae they settle and attach to some hard

substrate and become anemone

Phylum Platyhelminthes

1. Platyhelminthes are flatworms

2. They are soft, wormlike animals with flattened elongated bodies

3. Exhibit some important STRUCUTRAL advances over the cnidarians

a. Triploblastic (3-distinct tissue layers)

b. Ectoderm, endoderm, and mesoderm

c. They are bilaterally symmetrical – can be cut down the middle (vertically and the

halves are the same)d. Several well developed organs

e. So the main three are well developed organs, triplobastic structure (3 distinct tissue

layers) and then bilateral symmetry

f. Bilateral symmetry is characteristic of more advanced mulitcellular organisms except

for adult echinoderms



g. Platyhelminthes are flatworms that are soft and have flattened elongated bodies and

many structural advantages over the cnidarians 1

h. Triploblastic 3 distinct tissue layers

i. Bilateral symmetry (usually among higher metazoans)

j. Advanced organs: nervous excretory digestive reproductive nervous digestive

reproductive nervous and muscular

k. Some are now parasitic

l. Parasitism caused them to lose some of their modifications in these organs

Classification

Phylum Platyhelminthes- flatworms

Class Turbellaria (free-living flatworms)

1. Mainly free-living flatworms

2. Both freshwater and marine3. Flattened dorsoventrally bodies

4. Ciliated epidermis

5. Mouth usually ventral leading into the gastrovascualr cavity

Class Trematoda (flukes)

1. Parasitic animals

2. External tegument secreted by underlying cells

3. Ovoid body with one or two suckers for attachment to host

4. Gastrovascular cavity usually with two main branches

5. Very complex life style involving larval stages and alternate hosts

Class cestoda (tapeworms)

1. Elongated body with specialized scolenx with hooks and/or suckers for attacfhemnt to host;

2. Body divided transversely into a series of proglottids:

3. Thick external tegument

4. Mouth and digestive tract absent

5. Usually with compelx life cycle involving alternate hosts

Laboratory exercises

Class Turbellaria (free-living flatworms)

They have a head with auricles (organs sensitive to touch) and eye spots

1. Head is a major directing organ of the body and then there are a lot of muscle contractions

2. Incomplete gut so the mouth is in the center of the body

3. Cilia on the ventral surface on the body to help with the smooth, gliding locomotion



4. Carnivore

5. When flipped over uses head and muscles contractions to flip the whole body over

6. Swings head when looking for food, if senses the touch it alerts the auricles dugesia planarian

belongs to the class turbellaria

7. Triploblastic yayay

8. Know that these are dugesia planaria class turbellaria (flatworms)_

9. The more stained means lots of fibers

10. 3 layered gastrovascular cavity

11. Incomplete gut so the pharynx is in the middle of the body

12. Head, auricle and eyespot what where is the diverticula

13. Diverticula is the smaller lateral branches

14. There is 3 layered gastrovascular cavity (one anterior and 2 posterior)

15. Reproduction is hard to see because so small

16. Each individual has both male and female sex organs so is monoecious

17. Don’t usually self -fertilize

18. Instead one secretes sperm that is picked up by the other worm and carried to the oviduct of

the female organs in the other worm to fertilize the eggs and are eventually released to

develop directly into young worms

19. Mainly use asexual reproduction because they are great regenerators they break apart into 2

parts and then regenerate the rest of the missing structures

Phylum Pletyhelminthes

Triploblastic; bilateral symmetry; and advanced organs (reproductive, excretory, nervous, and

digestive) so they are more structurally advanced than the cnidarians that are diploblastic!

Class turbellaria (free-living flatworms)

Dugesia- spp planaria

Class Trematoda (parasitic flukes)

Hooks or suckers

Class Cestoda (tapeworms) lake head and gastrovascular cavity

Scolex with hook and/or suckers and have proglottids

Have well developed suckers for attachment, one located in the region of the mouth and one at the

intestine branching just above the uterus

The outer layer is called the tegument- it is an extension of cells embedded in the body wall

The tegument is an extension of cells embedded in the body wall

Tegument has complex structure and so does a tapeform



Both the digestive tract and reproductive systems are well developed

The digestive tract and reproductive systems are well developed

Clonorrchsislkls

The fluke has three specific hosts and it needs them to be available at the specific time or else they

will die (man, snail, and fish)

Life-cycle of clonorchis 0ccurs from eating raw fish

1. Humans are infected by eating raw fish

2. Fertilized eggs are released into the bile ducts because the adult worms live in the bile ducts (

so they secrete the fertilized eggs into the bile ducts)

3. Eggs pass through small intestines and end up in feces

4. If feces get into water then a specific spp of snail might consume them (1st intermediate host)

5. They will hatch into larval formation (miracidium) inside the digestive system of the snail

6. Miracidium lives in the tissues of the snail

7. Then undergoes many other larval stages (sporocyst, redia, cercaria)

8. And it reproduces asexually to reproduce thousands of new larvae

9. The cercaria stage is the last larval stage

10. The cercaria escape from the snail, get into the water and enter the second host the fish

11. It burrows under the fish skin and sheds its tail when it comes into contact with it!

12. This is the metacercaria metacercaria

13. If the fish isn’t cooked enough then it is consumed by man (3rd intermediate host) and enters

the bile ducts and grow to become adult clonorchis (flukes) and complete the life cycle

Life cycle stages of Fasciola

1. It is similar to the Clonorchis but the eggs hatch in the water and the miracidia search for the

snail, then the cercaria that is released doesn’t find fish but ncst on vegetations and the

herbivore gets infected by eating vegetations that there are metacercaria

2. The adult is a lot larger than other trematodes (tapeworms)

3. Common liver fluke in sheep, goats and sometimes humans

Fascolia is the common liver fluke important for livestock (sheep, goats, and sometimes humans)

Class cestoda (tapeworms)

1. Dog and cat tapeworms – taenia pisiformis

2. Highly specialized internal parasites

3. Have 3 sections of the body: 1. Solex that has 2 suckers 2. The hold fast organs with suckers or

hooks neck is followed by the hold fast organs, 3. The strobilla (the rest of the body that

contains the proglottids

4. Tapeworm is divided into many sections called proglottids



The scolex is the first part, then there is a hold-fast organ that has hooks or suckers that is followed by

a narrow neck, where the proglottids are asexually produced and then the stobilla is the rest of the

body that has proglottids that are not really segments because they are in each owntheir own

A proglottid is a COMPLETE REPRODUCTIVE UNIT WITHIN ITSELF

TAPEWORMS DO NOT HAVE A MOUTH OR A DIGESTIVE TRACT SO THEY ABSORB FOOD THROUGH

THEIR SKIN

PHYLUM NEMATODA

1. Pseudocoelomate- a body cavity that is fluid-filled but is not derived from the mesoderm

2. Used to be classes of phylum Aschelminthes but now belong to own separate phylum (phylum

nematode)

3. Nematodes and rotifer!

4. Their pseudocoelom is derived from a blastocoels of embryo

lab practical 1 (1)

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