WORMSclip

FLAT WORMS

~13,000

species

•Flatworms, liver flukes,

tapeworms

•Usually parasitic

•Can be free living and carnivores

•Can be aquatic or terrestrial

•Soft, Flattened, Acoelomates•Keeps body cells in direct contact with O2

•Bilaterally symmetrical •Cephalized•Have true tissues and organs•Two way gut

Body structure

•Have tissues and internal organs•Have all 3 germ layers.•Gas exchange occurs by diffusion through skin

Pharynx - muscular tube that extends through the mouth and through which food is ingested

Planarians have flame cells to regulate body fluid volume and composition•Body fluids are filtered across the flame cells.•Waste is excreted through pores to the outside.

A branched gastrovascular cavity is site of extracellular digestion and distributes nutrients about the body

    Simple nervous system: a. Paired ganglia form a brain.

       b. Sensory cells are in the body wall.

ReproductionSexual and asexual reproductionAsexual:Asexual:•Through regeneration -Able to regenerate any lost partsSexual:Sexual:•Hermaphrodites

•Both worms exchange spermFertilized eggs are enclosed in a cocoon and hatch in two to three weeks into tiny worms

Planaria

Classes1-Turbellaria

•Planaria and relatives •Free living, marine and freshwater•Two light-sensitive eyespots CLIP

2- Tremotoda• Flukes-blood, liver, lung • Head ends has suckers or hooks• Have reduced digestive, nervous, and

excretory systems.• Reproductive systems are well developed and

usually hermaphroditic • Parasitic- infecting the intestines of their host• Covered by teguments that protect them from

host digestive juices.– Examples:

•Schistosoma mansoni- blood fluke•Burrow through skin, lay eggs in

intestines and past out of body•Cause tissue decay

3-CestodaTapeworms•Absorbs nutrients through body• Taenia echinococcus -Can grow to 30 ft long -Has hooklets (Scolex) for attachment•No digestive system•Absorb nutrients directly through skin•Proglottids

-Segments of the worm

Each proglottid segment contains a full set of both male and female sex organs

Humans can be infected by eating beef that has not been cooked wellThe tapeworm attaches to the lining of the host with suckers and hooks

•A tapeworm scolex contains hooks and suckers for attachment to intestinal wall of host.

• Behind the head is a short neck and then a long string of proglottids.

Cow eats grassCow eats grassEggs hatch and burrow into cow’s muscles, where they can become dormant

Life cycle of TapewormTapeworm releases packets of eggs which exits with the host feces. Some eggs end upon grass on in field

•The blood flukeSchistosoma infects200 million people,leading to body pains,anemia, and dysentery.

ROUND WORMS

~500,000

species

•Roundworms (nematodes), hookworms

•Free-living and parasitic

•Aquatic and terrestrial

•Shaped like thick threads and tapered

on both ends

Body•Unsegmented, bilateral symmetry•Pseudocoelom•One way gut•Exchange gases through body walls-through diffusion

Movement:Contracting muscles -whip-like motion from longitudinal muscles

not for the

squeamish

Reproduction:

-Most species have

separate sexes

-Internal fertilization

DiseasesTrichinosisTrichinosis

--Humans, Pigs-In humans, can be contracted by eating infected pork.-Symptoms include abdominal pain, nausea, puffy and swollen face, headache and vomiting. Can have permanent damage to the heart muscles.-Recovery in about 6 months-5% of cases are fatal

Trichinella spiralis

trichina worm: Trichinosis

• Trichinosis

  After maturation, female adult burrows into wall of small intestine and produces living offspring that are carried by bloodstream to skeletal muscles where they encyst.

Muscle Biopsy Showing Trichinosis

Ascarid Worm:•Matures in the intestines of the host•Eating vegetables that are not washed

Hookworms:•Soil•Walking barefoot•anemia, malnutrition, and in children causes under-development

Filarial Worm•Tropical regions•Lives in blood and lymph vessels of birds and mammals•Usually causes elephantiasis

•Endemic in central Africa, Turkey, India, Southeast Asia, Australia, Philippines, and South America •transmitted by mosquitoes •After infection, the adult filarial worms migrate to and live in the lymphatic ducts of humans.  There, they clog up the blood vessels and cause the enlargement of the various body parts.  The worms then infiltrate connective tissue.

Guinea worms

• The worms mate. – Males die soon after, but pregnant females

continue to grow. – As adults, each threadlike worm can be three

feet long and harbor three million embryos. More than one guinea worm can infect a person at the same time.

• About eight months later, the female prepares to expel mature embryos by migrating toward the skin surface.

• Extreme pain occurs as the worm emerges from under the skin, often around the infected person's ankle.

• The pain is temporarily relieved by immersing the area in water, an act that contaminates the water and starts the cycle again.

•Contaminated water containing infected water fleas •Once in the human intestine, larvae burrow into surrounding tissue.

SEGMENTED WORMS

~12,000 species

•Segmentation allows a high degree of specialization of body regions.

–Groups of segments are modified for different functions.

•Ranging in length from less than 1 mm to 3 m for the giant Australian earthworm.•Annelids live in the sea, most freshwater habitats, and damp soil.

Diffusion of O2 and CO2 through moist skin

Segmented, Coelomates, Bilateral symmetryOne way gut Ex: Earthworms, leeches

Movement:-By alternating the two groups of muscles

1- Longitudinalshorter or fatter

2- Circularlonger or thinner

-Setae: bristles

animation

Feeding and Digestion:Feeding and Digestion:-Feed by sucking in soil and decaying matter-Earthworms move food through the pharynx-esophagus-crop-gizzard-intestines

•A muscular pharynx draws food into the mouth. •Food is stored in a crop and ground up in a muscular gizzard.•Gizzard can contain sand to aid in breakdown.

Chem Mech

               

             

             

           

                      

               

IntestineGizzard &

CropPharynx

Absorption- Large folds in the upper surface of the intestine –typhlosole (increases surface area)

• Closed circulatory system

• Heart consist of five pairs of aortic arches

• Blood contains hemoglobin

Hearts

Nephridia (in each segment) for excretion of nitrogenous wastes, urea.

•Wastes are discharged through exterior pores

Metanephridia of an earthworm

• Excretory system involves nephridia. – a. Coiled nephridia tubules in each

segment have two openings: one is a ciliated funnel that collects coelomic fluid, and the other is an exit through body wall.

– b. Between the two openings, a coiled nephridia tubule removes waste from blood vessels.

•Reproduction:•Sexually•Some have separate sexes and some are hermaphrodites (earthworms and Leeches)

•Earthworm: Clitellum secretes slim that contain eggs and sperm- the ring then becomes a cocoon- young worms hatch a week later.

The received sperm are stored while a special organ, the Clitellum, secretes a mucous cocoon.

• Nervous system has a brain connected to a ventral solid nerve cord; a ganglion is in each segment.

• Long ventral nerve cord leads from brain to ganglionic swellings and lateral nerves in each segment

nerve cord on the body cavity's ventral surface

Classes Classes of Annelida:of Annelida:1- Oilgochaeta1- Oilgochaeta--

•Stream-lined bodies, few setaeStream-lined bodies, few setae•Earthworms, Tubifex WormsEarthworms, Tubifex Worms

2. HirudineaLeeches

Moist-tropical Climates•most are parasites

use suckers to attach to host and blade-like teeth to make cut in host’s skin.

once used by doctors for bloodletting

hermaphroditicaquatic and terrestrial

Were used to treat medical conditions-Keep blood from coagulating by hirudin, an anticoagulant in their saliva

3. Polychaeta (marine worms )Sandworms, Blood Worms

•Live in Cracks and Creases in coral reefs, sand, mud, piles of rocks.

• Parapodia are paddle-like appendages used in swimming and for respiration.

Ecology:•Recycling in nature•Diet of many birds

•Diet of fish

The evolutionary significance of the coelom cannot be overemphasized.

– The coelom provides a hydrostatic skeleton that allows new and diverse modes of locomotion.

– It also provides body space for storage and for complex organ development.

– The coelom cushions internal structures and separates the action of the body wall muscles from those of the internal organs, such as the digestive muscles.

Coelom

Name of Disease

Causative Organism

Vector Definitive test

Human Ascaroid

Ascaris lumbricoides

Drinking infected (sewage) water

Stool sample

Hookworm Necator americanus

Walk barefoot on soil w/ juvenile

Fecal Sample

Trichinosis Trichinella spiralis

Eating pig meat w/encysted T. Spiralis

Tissue Sample of Muscles look for

encysted T. Spiralis

Elephantiasis

Wucheria bancrofti

Mosquito Bite Blood Sample look for

microfilaria

Guinea Worm

Dracunculus medianansis

drink water/ swallow cyclops

blood test, look for microfilaria

River Blindness

Oncocerca volulus

Black Flies "

Eye Worm Loa loa Deer fly "

Dog Heartworm

Dirofilaria immitus

Mosquito, mostly Aedes culex "