WormsChapter 27

27 – (1-3)

1. Worm characteristicsA. Bilateral symmetry (Mirror image)B. Cephalization- concentration of brain-like structure in the anterior area.C. Digestive and circulatory system present

2. Phylum AnnelidaA. Segmented worms

1. Segments filled with fluid. a. Segmentation – body divided into

smaller sections.B. Longitudinal muscles

1. Run up and down and are used to shorten each

segment.C. Circular muscles

1. Surround the longitudinal muscles.2. When contracted they lengthen the segments.

3. Classes of Phylum Annelida

A. Oligochate

1. Means “few bristles”

2. Setae – bristles found on the ventral surface of the earthworm, used for traction and movement.

3. ex. Earthworms

II. Earthworm Body Parts–A. Mouth–B. Pharynx- sucks in soil–C. Esophagus – Food Tract–D. Crop- Temp. food storage.–E. Gizzard – Grinds food–F. Intestines – Food travels through–G. Anus – Waste is removed– .

–H. Dorsal Blood Vessel – Top, transports blood from tail to head.

–I. Ventral Blood Vessel – Bottom, transports blood form the head to tail.

J. Clitelum-specialized segments that secrete a mucus ring into which eggs and sperm are released. Fertilization takes place within the ring of mucus.

• K. Aortic arches – 5 hearts• L. Septa – thin tissues that

separate each segment holding skin tightly around EW inner organs.

Fun Facts about Earthworms

• Earthworm main activity is burrowing. While burrowing, they create holes, and tunnels that loosen the earth and aureate the soil. This allows water to run through it easier than roots can penetrate through the soil more efficiently. (Excellent Gardeners)

• Earthworms feces, called casting, actually fertilizes the grass after it passes through the earthworms body. The casting is filled with vegetation that provides nutrients to the soil.

B. Polychaetes

1. Means “many bristles”

2. Live throughout the oceans

3. ex. Plume worm, bristle worm, sand worm

C. Hirudinea1. live in the tropics, suckers on each end,

part time parasite, attaches only when feeding, still used in medical purposes. 2. ex. Leeches

•Platyhelminthes- Flatworms

• and Nematoda - Roundworms

Phylum Platyhelminthes

A. Common name flatworms “platys” = flat, helmins = worm.

B. Simplest worms.

C. Bilateral symmetry.

D. Flat, long and only few mm thick.E. Can be harmless or parasitic (harmful).F. No respiratory or excretory systems.G. Eye spots are used to detect presence or absence of light.H. Nervous system present.

6. Classes of Phylum PlatyhelminthesA. Turbellaria

1.Carnivores or scavengers.2. Located in lakes, streams, and oceans.3. ex. Planarian

. Planaria body parts• a.) Pharynx – Tube-like structure on the

ventral surface that extends to suck in food. (Mouth and Anus)

• b.) Eyespot – sensory structure on head that senses light and dark.

• c. )Auricles – (sensory lobes) ear-like bumps on right and left side of head used for responses.

• d.) Has the ability to regenerate any body part completely with the exception of the tip of the tail

Planarian

B. Trematoda

1. Parasitic – lives in blood of host.

2. Less than 1 cm but causes serious damage.

3.Native to Africa, Asia, S.A. and Central America.

4. ex. Flukes

C. Cestoda

1. Parasitic flatworms

2. Live in intestines of host

3. ex. Tapeworms

D. Tape worms

1. Has no gut, digestive system, mouth and nervous system of their own.

2. Scolex – head area where the suckers are to

attached to the intestines of host.

a. Rostellum- contains hooks on the tip of the scolex for attachment.

b. Suckers surround the scolex also for attachment.

3. Proglottids are segments with male and

female parts that will break off when filled with fertilized eggs and drop out of the feces of the host animal.

7. Phylum Nematoda

A. “Nematos” = thread (round worms)

B. Thrive in marine sediments, free living, live in soil, salt flats, tropic and polar waters.

C. Most parasitize marine invertebrates.

D. Size range from 1 mm to more than 1 m.

E. Digestive tract – mouth and anus at opposite ends.

1. Simplest animal with this digestive tract.

8. Round worms and Human Diseases

• A. Parasitic roundworms – Trichinella worm, Filarial worm, Ascarid worm and Hook worm.– 1. Trichinella – Trichinosis is a disease that

affect the organs and tissues. Larvae are released attacking organs causing tremendous pain. They also form cysts in the muscles. Human gets it by eating raw or under cooked pork.

• 2. Ascarid Worm – Ascaris can cause malnutrition by absorbing all digested food in the intestines of a human. It can also grow large in numbers and block intestines.

–A. Received by eating poorly washed veggies and food.

Guinea Worm

Guinea Worm

Parasitic worm- ascaris

Loa Loa worm also from insect bite

This is how you remove it!

• 3. Filarial Worm – live in the blood and lymph vessels of birds and mammals. Transmitted through biting of an insect, mosquitoes. Large numbers can block fluid passage ways causing inflammation.

• Example - Elephantiasis

Elephantiasis -The disease is caused by a microscopic, parasitic

worm that invades the body's lymphatic system.

Dog Heartworm