INVERTEBRATES = NO BACKBONE!

Symmetry

• Definition- Similar in size, shape, and position

• Three types of symmetry

1. Spherical

2. Radial

3. Bilateral

Spherical SymmetrySpherical Symmetry:Everything is the same in all directions (as if on the surface of a sphere).

                         

                         

The pollen of the hollyhock exhibits spherical symmetry (magnification x 100,000)

Radial Symmetry

Bilateral Symmetry

Sections of the Body

• Anterior = Front

• Posterior = Tail

• Dorsal = Top/Back

• Ventral = Underside or Belly

Worms

• Phylum: PLATY Helminthes – flatworms

• Planaria- Free living organism (NOT a parasite!)

• CAN regenerate

• Hermaphroditic- Have both male and female reproductive structures

• Class: Trematoda- flukes-parasites

Worms:Unique Life Cycles

• Sheep Liver Fluke (Herma)

1. Found in the liver as an adult

2. Releases eggs in waste

3. Eggs become larvae

4. Enter a snail

5. Forms cysts

6. Cysts on the grass are eaten by animal!

Sheep Liver Fluke

Worms: Unique Life Cycles

• Cestoda (Herma)

1. Tape worms enter the body as cysts

2. Attach to intestines

3. Grow head called Scolex

4. Develop body sections called PROGLOTTIDS

Cestoda

Worms: Unique Life Cycles

• Nematoda – Round worms

1. Enters in food and water

2. Eggs become larvae

3. Burrows hole in intestines

4. Grows and produces 200,000 eggs per day!

5. Example:Ascaris

Ascaris

FUN FACT!!!

• 1/3 of world is infected with round worms!!

Worms: Unique Life Cycles

• Hookworms1. Eggs and larvae are in warm, moist, damp soil2. Enters human body through the bottom of the foot3. Enters blood stream and travels to intestines.4. Grows and develops eggs passed out in waste

Worms: Unique Life Cycles

• Heartworms

1. Found in dogs

2. Animal feces attach to heart vessels

Worms: Unique Life Cycles

• Trichina Worm (Trichinosis)

1. Forms cysts in muscle of pigs and hogs (pork)

2. Most enter in foods and water

Trichina Worm

Annelids-Segmented Worms

• Earthworms, Red worms- (Night crawlers)

• Bilaterally symmetrical, segmented worms

• Well developed Cephalization

• Closed circulatory system

• Hermaphroditic (Non-Parasites)

• Parasites- Leeches- Blood Suckers