Zoology Manual II

Home , Mesentery (zoology), Planula, Polyp (zoology)

Zoology II

6. Present the preserved cnidaria on a tray or the model/transparencies. Ask

what the skin of the cnidaria is like. Have the children verbally describe

their observations. Explain that there are two layers to the skin of the

cnidaria, the ectoderm and the endoderm.

7. The skeleton is an outer layer of tough, transparent perisarc. It supports

and protects the cnidaria.

8. Circulation occurs through the movement of fluid between two tissue layers

(ectoderm and endoderm) that circulate the food to each cell.

9. Respiration has no structural specialization, but occurs through diffusion

between cell and the water.

10. Reproduction is sophisticated. Labeled ‘alternation of generations’, the

two generations are the hydroid and the medusa. The hydroid reproduces

asexually; its offspring is the medusa. The medusa reproduces sexually;

its offspring is the hydroid.

11. Lay out the pictures of the main characteristics / internal parts of the

cnidaria. Distribute the labels for the children to read and to match to the

appropriate pictures. Read the definitions and allow the children to match

the definitions to the pictures and labels.

12. Present the booklet and display the wall chart.

Activities:

1. Allow the children to sit and observe the anemone.

2. Allow the children to dissect or examine the slide of the hydra under a

microscope.

3. The children should make their own booklets, tracing or drawing the

pictures and writing the definitions.

4. Visit an aquarium or marine biology museum to see anemones or hydra.

NOTE: It is advised that the presentation be divided over several days:

Days 1-5 Observe the live anemone

Observe the preserved hydra

Days 6-8 Dissect the hydra / view model and transparencies

Days 9-10 Introduce the pictures and labels, the booklet and

wall chart

NOTE ALSO: Greek: knide - nettle

koilos - hollow

enteron - intestine

Presentation 2: Life Cycle of the Jellyfish

1. Show the life cycle of the jellyfish to the children.

2. Name the parts of the life cycle of the jellyfish:

A. Sexual Reproduction: adult medusa, gamete (egg or sperm), blastula,

planula larva, polyp, bud, immature medusa, adult medusa.

B. Asexual Reproduction: polyp, bud, asexual larva, polyp.

3. Discuss the life cycle of the jellyfish:

A. Sexual Reproduction - The adult jellyfish contains either eggs or

sperm in gonads. Some species have both eggs and sperm in one

individual.

B. The Adult Medusa - The adult medusa releases eggs or sperm from

the gonads into the water. The gonads are located along the radial

canals.

C. The Gamete - The gamete is the egg or sperm released by the adult

medusa into the water. The egg and sperm unite to form the blastula.

D. The Blastula - The blastula is the microscopic fertilized egg.

E. The Planula Larva - The planula larva is free-swimming, using cilia

to swim through the water. The planula larva is solid with no mouth.

The planula larva metamorphoses into the polyp.

F. The Polyp - The polyp settles on a hard surface and remains

anchored to the hard surface through the winter. The polyp

reproduces asexually by budding to produce a colony of polyps.

In the spring, the polyps reproduce asexually to form stacks of tiny,

swimming, immature medusae called ephyra.

G . The Immature Medusa - The immature medusa grows and develops

into the adult medusa.

4. Discuss another life cycle of the jellyfish.

A. Asexual Reproduction - The jellyfish polyp reproduces by itself

without exchanging any genetic material with another polyp.

B. The Polyp - The polyp settles on a hard surface and remains

anchored to the hard surface through the winter. The polyp

reproduces asexually by budding to produce a colony of polyps.

C. The Bud - The bud forms on the side of the polyp and separates

from the polyp to become the asexual larva.

D. The Asexual Larva - The asexual larva grows and develops into a

polyp.

5. Encourage each child to repeat the functions of the parts of the life cycle

of the jellyfish.

6. Lay out the pictures of the life cycle of the jellyfish in a circle with the

adult jellyfish at the top center and going clockwise.

7. Distribute the labels for the children to match to the pictures.

8. When the children know the definitions of the parts of the life cycle of the

jellyfish, distribute the definitions for the children to read and to match to

the pictures.

9. Display the chart of the life cycle.

10. Place The Jellyfish Life Cycle classified nomenclature material on the shelf.

11. Place The Jellyfish Life Cycle booklet on the shelf.

12. Follow-up activities for the child:

A. Match the picture and label. (simple nomenclature)

B. Match the picture, label, and definition. (classified nomenclature)

C. Make a booklet of The Jellyfish Life Cycle.

D. Make a chart of The Jellyfish Life Cycle.

E. Repeat the above procedure for the sea anemone and coral.

Presentation 3: Internal Parts of the Sea Anemone - Detailed

1. Show the picture of the internal parts of the sea anemone to the children.

2. Name the internal parts of the sea anemone: oral disk, siphonoglyphs,

sphincter muscles, mouth, pharynx, gastrovascular cavity, ectoderm,

mesoglea, endoderm, mesentery, retractor muscles, mesenteric filaments,

gonads, and basal disk.

3. Discuss the internal parts of the sea anemone.

A. The Internal Parts of the Sea Anemone - The internal parts of the

sea anemone are oral disk, siphonoglyphs, sphincter muscles,

mouth, pharynx, gastrovascular cavity, ectoderm, mesoglea,

endoderm, mesentery, retractor muscles, mesenteric filaments,

gonads, and basal disk.

B. The Oral Disk - The oral disk is the disk around the mouth. The

oral disk extends inwards to produce the tubular gullet or pharynx.

The tentacles are attached to the oral disk.

C. The Siphonoglyphs - The siphonoglyphs are two grooves located

in the oral disk. The siphonoglyphs have many cilia which move

water, oxygen, and food particles through the pharynx and

gastrovascular cavity.

D. The Sphincter Muscles - The sphincter muscles contract and expand

the oral disk and the tentacles.

E. The Mouth - The mouth is in the center of the oral disk and is

surrounded by tentacles. Water, oxygen, and food particles enter

the sea anemone through the mouth. The mouth also squirts out

the waste material and acts as the anus in the sea anemone.

F. The Pharynx - The pharynx is the tubular connection between the

mouth and the gastrovascular cavity of the sea anemone. The

siphonoglyphs move water, oxygen, and food particles from the

mouth, through the pharynx, and into the gastrovascular cavity.

Internal fluid pressure in the pharynx and gastrovascular cavity

help to keep the upright shape of the sea anemone.

G . The Gastrovascular Cavity - The gastrovascular cavity is the digestive

system of the sea anemone. The cilia of the siphonoglyphs move

the water, oxygen, and food particles through the gastrovascular

cavity. Radial canals distribute dissolved oxygen and carbon

dioxide from the gastrovascular cavity to the outside layers of the

sea anemone.

H. The Ectoderm - The ectoderm is the outside layer of cells of the sea

anemone.

I. The Mesoglea - The mesoglea is the jelly-like substance between

the ectoderm and the endoderm of the sea anemone. The mesoglea

is a matrix of elastic collagen fibers that gives the shape to the sea

anemone and cements the ectoderm and endoderm together. The

mesoglea can also change the body shape.

J. The Endoderm - The endoderm is the inside layer of cells of the sea

anemone. The endoderm forms the lining of the gastrovascular

cavity.

K. The Mesentery - The mesentery forms internal partitions in the

gastrovascular cavity. The mesentery usually occurs in arrays of

multiples of six mesenteries.

L. The Retractor Muscles - The retractor muscles are longitudinal

muscles that are anchored in the mesoglea. The retractor muscles

retract the tentacles. The retractor muscles retract the mesoglea

for movement from place to place.

M. The Mesenteric Filaments - The mesenteric filaments are attached

to the gonads. Sperm and fertilized eggs are released through the

mesenteric filaments and out through the mouth.

N. The Gonads - The gonads contain the eggs and sperm of the sea

anemone. The sperm are released through the mesenteric filaments.

The eggs are held in the gonads until fertilization occurs. Once

the eggs are fertilized, they are released through the mesenteric

filaments. Some sea anemones are hermaphrodites, containing

both eggs and sperm, while others have separate sexes. Sea

anemones do not fertilize their own eggs.

O. The Basal Disk - The basal or pedal disk is the point of attachment

of the sea anemone to a surface such as a rock or coral reef. The

sea anemone can reproduce by splitting of the basal disk.

4. Encourage each child to repeat the function of the internal parts of the sea

anemone.

5. Lay out the pictures of the internal parts of the sea anemone from left to

right.

6. Distribute the labels for the children to match to the pictures.

7. When the children know the definitions of the internal parts of the sea

anemone, distribute the definitions for the children to read and to match

to the pictures.

9. Place The Internal Parts of the Sea Anemone classified nomenclature

material on the shelf.

10. Place The Internal Parts of the Sea Anemone booklet on the shelf.

11. Follow-up activities for the child:

A. Match the picture and label. (simple nomenclature)

B. Match the picture, label, and definition. (classified nomenclature)

C. Make a booklet of The Internal Parts of the Sea Anemone.

D. Make a wall chart of The Internal Parts of the Sea Anemone.

E. Repeat the above procedure for the jellyfish and coral.

Presentation 4: Classification and Research of the Phylum Cnidaria

1. Show the classification form to the children.

2. Say, “Scientists have classified living things into different categories

according to characteristics that they have in common.”

3. Say, “Cnidarians are animals. Cnidarians belong to the Kingdom Animalia.”

4. Say, “Cnidarians are simple animals with stinging tentacles. Cnidarians

belong to the Phylum Cnidaria.”

5. Say, “There are three classes of cnidarians:

Class Hydrozoa are the hydras. There are about 2,700 species in six

orders. The hydras are marine or freshwater. They are solitary or colonial

organisms. The life cycle can include the medusa and polyp, or one or

the other. The sexes may or may not be separate. Examples are the

siphonophores Physalia (Portuguese Man of War) and Muggiaea.

Class Scyphozoa are the jelllyfish. There are about 200 species in five

orders. The jellyfish are marine. They are solitary organisms. The medusa

is the dominant form of the life cycle. The sexes are usually separate.

Examples are Aurelia and Cassiopeia.

Class Anthozoa are the sea anemones, sea pens, and corals. There are

about 6,500 species in 12 orders. The sea anemones, sea pens, and corals

are marine. They are solitary or colonial organisms. The polyp is the

dominant form of the life cycle - there is no medusa form. The sexes are

separate or hermaphroditic. Examples are Metridium (common plumose

sea anemone), Corallium (red coral), Tubipora (tube coral), and Alcyonium

(dead man’s fingers coral).

the sea anemones. Sea anemones are soft-bodied cnidarians with a mouth

surrounded by stinging tentacles. Most sea anemones live on a hard

surface, cemented to the surface by secretions from the basal disk.

Barrett, Norman, Picture Library: Coral Reef, Published by Franklin Watts, New

York.

Dr. Keith Banister and Dr. Andrew Campbell, The Encyclopedia of Aquatic

Life, Published by Facts on File, Inc., New York, 1998, pages 172 - 181.

Kalmen, Bobbie and Walker, Niki, Life in the Coral Reef, Published by Crabtree

Publishing Company, New York.

Lynn Margulis and Karlene V. Schwartz, Five Kingdoms, Published by W.H.

Freeman and Company, New York, Third Edition, pages 218 - 223.

The Visual Dictionary of Animals, Published by Dorling Kindersley, New York,

pages 24 - 25.

MAIN CHARACTERISTICS/ INTERNAL PARTS OF INVERTEBRATES PLATYHELMINTHES

Material:

A set of pictures, labels, and definitions illustrating the main characteristics/

internal parts of the flatworm

A booklet of the main characteristics / internal parts of the flatworm

A wall chart of the flatworm

A live Playtyhelminthes

A preserved Playtyhelminthes for dissection / model or transparencies

Presentation 1: Main Characteristics of the Platyhelminthes

1. Bring a live flatworm before the children and observe it.

2. Allow the children to discuss what they observe.

3. Review the booklet of the Zoology Classified Nomenclature for

Platyhelminthes.

4. While observing the live flatworm, ask how the flatworm moves. Discuss

and explain this process. Some Platyhelminthes move by means of cilia

that cover the body, and some move by the contraction of muscles.

5. While observing the live flatworm ask how the flatworm breathes. Discuss

and explain this process. There is no specialized organ. Respiration occurs

by a process of diffusion.