Phylum: Platyhelminthe

To Know:Bilateral, Cephalization, Diffusion, Ectoparasite, Endoparasite, Eyespot, Fission, Flame cells, Flukes, Gastrovascular cavity, Hermaphrodite, Pharynx, Proglottids, Scolex

Understand:All organisms carry out the same body functions.

Be Able to Do:For platyhelminthe give: Body type How they carry out essential functions. Describe the ecological affects of each.

The Parasitic Way of Life:

Most parasitic animals, including parasite flatworms cannot replace lost parts.

Parasites may be either internal or external.

The size of the internal parasite is limited by the size of its host.

Intestinal parasites usually have hooks or suckers so they can cling to the walls of the host’s intestine.

The parasite is protected from being digested by a thick cuticle.

Certain systems are reduced or lost in parasitic worms (degenerated). The parasitic worm benefits by this since they have more body room for developing eggs.

Dispersal is a problem for internal parasites. At the larval stage, they may be free living or live

within another organisms.

Phylum: Platyhelminthe

Means:“Flatworm”

Description:

Soft-flattened worm that has tissue and internal organs.

Related terms: Platyhelminthe

Ganglia (Brain)Eyespot

Nerve cord

Gastrovascular cavity

Pharynx

Mouth

Endoparasite: Parasite that lives inside of its host.Related terms: Platyhelminthe

Ectoparasite:

Parasite that lives outside

the host.

Related terms: Platyhelminthe

Scolex:

Knob-shaped head

that contains

suckers or hooks and

absorbs nutrients.

Related terms: Platyhelminthe

Proglottids: Mass of reproductive organs.

Related terms: Platyhelminthe

Cerebral ganglia:

A pair of nerve-cell clusters that serve as a primitive brain at the anterior end.

Related terms: Platyhelminthe

Related terms: Platyhelminthe

Eyespot: Detects changes in quantity and quality of light

Flame cells: A cell that has flagella or cilia that move waste products through the body.

Related terms: Platyhelminthe

Related terms: Platyhelminthe:

Flukes: A parasitic flatworm of the class Trematoda or Monogenea.

Related terms: Platyhelminthe

Pharynx: A muscular tube that leads from the mouth to the gastrovascular cavity.

Classes of Flatworms:

Turbellaria:

• Planarian: free living

Most are marine, but some inhabit freshwater and there are terrestrial ones as well.

• The two pictured are from down under and use slime to move around.

•

Flukes are parasitic and infect blood organs.

Trematoda:

Classes of Flatworms:

Native to Africa and Asia, South

and Central America.

Classes of Flatworms:

Flukes live part of their life cycle in snails and another part in one or more host.

a. 500 to 1000 eggs

How many eggs can this fluke lay?

b. 1200 to 8800 eggs

c. 9000 to 60,000 eggs

d. 10,000 to 100,000 eggs

Classes of Flatworms:

Flukes live part of their life cycle in snails and another part in one or more host.

a. 500 to 1000 eggs

How many eggs can this fluke lay?

b. 1200 to 8800 eggs

c. 9000 to 60,000 eggs

d. 10,000 to 100,000 eggs

Classes of Flatworms:

•

Flukes live part of their life cycle in snails and another part in one or more host.

A fresh water fluke that lives in fish and water birds and occasionally humans. (Not adapted to humans, so they don’t live long.)

Causes:A short lived rash known as “swimmer’s itch”

Problems:

Eggs can clog blood vessels causing swelling, tissue decay in lungs, liver, spleen or intestine.

Other symptoms:

Rash, fever, cough, body pain in early stages. Dysentery, emaciation (thinness), and weakness in later stages.

Problems may occur:

From improper sewage disposal.

Class: Cestoidea Tapeworms

The SCOLEX – a knob-shaped head, contains suckers or hooks that attaches it to the intestines and absorbs nutrients.

Tapeworms:

PROGLOTTID: Mass of reproductive organs

NOTE: The proglottid contains both male and female reproductive organs. These proglottids can fertilize either other tapeworms or other proglottids of its own body.

Classes of Flatworms:

Tapeworms:Fertilized tapeworm’s eggs are released when mature proglottid break off and rupture. One proglottid contains 100,000 eggs. These eggs are pass out through the feces.

Ecology:Procotyla fluviatilis, and other flatworms, are important parts of healthy streams, ponds, and lakes. They need clean water with lots of oxygen, so when we don't find them, that tells us the water is not healthy. They also provide food for animals, like dragonflies, when they are young. Dragonflies later help us control pests (like mosquitoes) when they are adults.

Symmetry

Bilateral

Movement/Support(Skeleton)

Cilia on outside of body

Muscles cells – quick reactions

Hydrostatic skeleton

Feeding(Digestion)

One opening digestive system

Gastrovascular cavityEat through pharynx

Carnivores and Parasites

Respiration

Diffusion of oxygen and carbon dioxide through body wall

ExcretionFlame cells – filter out excess water & waste, join as network

Circulation

Diffusion moves oxygen and food around to cells

Response/Nervous

Ganglia – mass nerve cells controlling nervous system

Eyespot

Cephalization

Two long nerve cord

Reproduction

Hermaphrodite (both sexes)

Asexual

Fission – organism split in two

SexualInternal fertilization

Special Features

Three germ layers1 ectoderm

2 mesoderm

3 endoderm

Special FeaturesAcoelomates (no body cavity)

Tegument: On the external surface of a parasitic invertebrate. It is a layer that counters the defenses of the host’s body.

RoundwormsPhylum: Nematoda

Roundworms:

Phylum:Nematode

Latin for:Round worm

Defined as:Unsegmented worms that have pseudocoeloms and digestive systems with two openings, a mouth and an anus.

Trichinosis:A disease caused by a parasitic roundworm that results from eating larvae in undercooked meat. Characterized by diarrhea, fever, abdominal and muscle pain. Affects the lungs, nervous system and heart.

Examples:

Filarial worm:Passed by the bit of a mosquito causing severe infection, which may block the passage of fluids within the lymph vessels.

Examples:

Filarial worm:Causing: Elephantiasis

A disease in humans that is caused by filarial worms and that is characterized by fluid accumulation that results in thickened skin around the swollen extremities.

Ascarid: Causes: malnutritionOccurs when eggs are ingested. The egg releases a larval worm which penetrated the small intestine and enters the blood stream. It is carried to the liver and the heart and enters the pulmonary circulation and breaks free in the alveoli The ascaris grows and molts. The larvae passes from the respiratory system to be coughed up, swallowed, and thus returned to the small intestine. Here they mature into adults male and female worms and fertilization occurs. The female can produce as many as 200,000 eggs per day for a year. These fertilized eggs become infectious after 2 weeks in soil and can persist in soil for 10 years or more.

Examples:

Hookworm:

Can cause anemia, weakness and poor growth in individuals.

Examples:

Pinworm:

The adult pinworm inhabits the large intestine, the eggs are laid outside of the anus during the night, creating a severe itching sensation.

Examples:

Caenorhabditis elegans:

A nematode with exactly 959 cells. They are transparent, which allows researchers to watch each cell develop.

• Takes on 12 hours from fertilization of the egg till it hatches into a juvenile worm.

• In that time, successive cell divisions produces 671 cells, in which 113 are programmed-to-die, leaving 558 in the worm that hatches.

• This “programmed-to-die” characteristic is valuable to researchers studying the aging process.

Examples:

Symmetry:

Bilateral:

Movement/Support(Skeletal)

Simple muscles

Hydrostatic skeleton

Feeding(Digestion)

Many are carnivores

Two opening digestive tract

Extracellular

Respiration

Diffusion of oxygen and carbon dioxide through body wall

                                                     

    

                                                     

    

Excretion

Diffuse waste through body wall

Circulation

Diffusion moves oxygen and food around to cells

Response/Nervous

Cephalization: has several ganglia

Simple nervous system

Several sense organs (detect chemicals)

ReproductionSexual

Internal fertilization

Hermaphrodites

Special Features

Pseudocoelom (false body cavity)

Explain why tapeworms can survive without a digestive system.

They absorb nutrients directly from the host’s digestive tract through their

tegument.

Note proglottids are reproductive sections that may be expelled

in the host’s feces and releases eggs.

If eaten, the eggs develop into larvae, which form a cyst.

Life cycle of the Schistosome.

Fertilized eggs leave the primary host in the feces or urine.

Ciliated larvae swim through the water.

Larvae burrow into a snail.

Larvae produce asexually in the intermediate host.

Tailed larvae swim through the water.

Larvae penetrate the skin of a human.

Larvae enter a blood vessel and develop into adults.

Phylum: Annelida

Means:

“Little Ring”

Description:

Worm with segmented bodies that has a true coelom that is lined with mesoderm.

Body Plan:

Bilateral

Annelids body is divided into segments by:

Septa (septum)

Internal wall between

segments.

Earthworm have an anterior, posterior, dorsal and ventral side.

Anterior: The segmented end is darker and more pointed than the posterior end.

Dorsal: Is darker than the ventral side. The ventral side is flatter and has setae.

How can you identify the difference between each of them?

The mouth of the earthworm cannot be seen because if is covered up by an upper lip called the Prostomium.

Prostomium

Flap over the mouth in annelids.

Digestive System parts:

Mouth: Opening into system, located on the anterior end.Pharynx: Sucks in food.Esophagus: Connective tube between pharynx and crop.

Crop: Stores food temporarily.

Digestive System parts:

Gizzard: Grinds food.

Intestine: completely digests and absorbs the food.

Anus: Opening through which undigested materials is released.

Aortic arches: Pumps the blood (Heart) – 5 pairs.

Dorsal Blood VesselBlood vessel on the back of the worm. Blood flow towards the anterior end

on the dorsal side and towards the anus on the

ventral side.

Clitellum:

Secretes a slime ring in which the eggs and sperm are released.

Seminal receptacle: Where sperm from the other worm is stored.

Symmetry:

Bilateral

Skeleton:Hydroskeleton

Movement:Longitudinal muscles: When they contract, they shorten the segments.

Circular muscles: Ringed shaped muscles that will lengthen the segments when they contract.

Digestion:Extracellular

Respiration: DiffusionEarthworms absorb oxygen and give off carbon dioxide through the skin. Skin must be moist.

Excretion: NephridiaRemoves metabolic waste. There are two in each segment except the first and the last.

Circulatory:Closed

Nervous: CephalizationThe nervous system coordinated the worm’s movement. There is a very small Dorsal nerve center in segment 3 (brain) and a nerve cord.

The ventral nerve cord runs down the middle of the ganglia (enlarged nerve center) in each segment. Earthworms are sensitive to light and sound.

Reproduction: HermaphroditesExternal fertilization

Earthworms are hermaphrodite. Sperm is produced in the testis are stored in the seminal vesicle until mating takes place. Sperm received from another worm is stored in seminal receptacles.

During mating sperm travels from the seminal vesicles of one worm through openings in segment 9 and 10. Eggs leave the ovaries through opening in segment 14. they are released into a slime ring secreted by the clitellum; sperm (from seminal receptacles) is released on top of them.

Mating in terrestrial worms:Worms usually mate at night in late summer, but will mate other times if the conditions are favorable. When a worm meets another worm of the same species and read to mate, they will lie side-by-side, head to head. The head ends becomes enveloped in a mucous tube which helps hold them together while the sperm is exchanged.

A few days after mating the clitellum will secrete a substance that will encircle and become the cocoon wall. The clitellum glands will secrete albumin. As the cocoon moves forward towards the head, eggs and sperm are released. This seals as it passes off the head. These cocoons can be formed every 3 or 4 days.

There are between 100 to 180 segments in a earthworm. Body parts are located in the same segment of each earthworm.

If you are looking for:

Mouth 1

Look in segment:

Heart (Aorta arches)

17 - 18

Brain

7 - 9

3

GizzardIntestine 19 to the endClitellum 33 - 37

AnnelidsAnnelids have the most complex body structure of all worms. Their body is divided into segments that are filled with fluid and are tightly sealed by body walls called septa. Most live in salt water, although some live in fresh water or on land. They have a true body cavity or coelom.

Bristle worm

Classes of Annelids:

Oligochaete: means “few bristles”

• They have setae, bristle that dig into the soil providing traction

• They swallow and grind up incredible amounts of soil and organic matter.

• They aerate the soil and recycle many nutrients, such as nitrogen.

Example: Earthworm

Classes of Annelids:

Polychaetes: means “many bristles”• Each body segment includes a pair of paddle-like

structure tipped with bristles.Example: Bristle worm, Sandworm and Plume worm.

Bristle worm

Sandworm

Plume worm

Classes of Annelids:

Hirudinea:

Example: Leech

SKBloor Production