Flatwormsor

Who Got Run Over by the Mail Truck

I. General Traits or Characteristics

• A. Simplest animal that possesses bilateral symmetry

B. Bilateral symmetry

• 1. recall that organism has a dorsal and ventral surface

• 2. also has a left and right side

C. Cephalization

• 1. concentration of nerve tissue in the head of the animal

• 2. two ventral nerve cords running posteriorly

• 3. anterior sensory organs

D. TriploblasticE. No coelom

F. Possesses organ systems

• 1. digestive system– a. Single opening– b. Tubular

muscular pharynx– c. Single arm

leading anteriorly– d. Forked branch

leading posteriorly– e. Note highly

branched nature

Muscular pharynx

Flatworm feeding

• http://www.martinmicroscope.com/HDVideoDownloads.htm

• http://www.youtube.com/watch?v=Fq_aSR5FK0Y&NR=1&feature=fvwp

2. Reproductive system

• a. Hermaphroditic• b. Both sexes on

same organism

3. Excretory system

4. No respiratory nor circulatory system

• Why not?

II. Classes of platyhelminthes

• A. Turbellaria• 1. already described• 2. planaria and relatives

B. Monogenea

• 1. parasitic forms• 2. ectoparasites

C. Trematodes-schistosomiasis

D. Cestoidea-tapeworm

• 1. scolex• 2. proglottids• 3. de-evolution• 4. reproductive machine• 5. pieces of “rice” in

feces

This is HUGE!!!

Once you are attached…

That is what you call “knockers”

Aren’t parasites fun?

What does this say??