Worms—eeyuu…..

 

Nemotodes and tapeworms and earthworms…oh my!  All of the organisms in today’s notes share bilateral symmetry and are triploblastic exotherms with organ level organization in the adult forms.

 

I. Acoelomate Worms:

 

Characteristics:

 

Outer covering:

·         Syncytial:

 

·         Rhabdites:

 

Digestion:

Excretion:

·         Flame cells:

 

Skeleton/Movement:

 

 

Circulation/Respiration:

 

Nervous System:

 

 

Reproduction:

·         Asexual:

 

·         Sexual:

 

 

Phylum Platyhelmenthes: flatworms: include the free-living Turbellarians and the parasitic Trematoda and Cestoda

·         Turbellarians: (Planarians) free-living worms

 

o   Dugesia

 

 

·         Trematodes:  (Flukes) parasitic

 

o   Most trematodes have complex life cycles, with larval stages parasitizing one or more species that are different from the host of adults.

 

o   Schistosoma: blood flukes: cause a disease known as Schistosomiasis.

 

o   Clonorchis sinensis:liver flukes: found mainly in eastern Asia and south Pacific Asia.

 

·         Cestodes: (Tapeworms)

 

o   Proglottids

 

o   Scolex

 

o   Microvilli

 

 

Phylum Nemerta: Ribbon worms

·         Proboscis:

 

·         Stylet:

 

·         Digestive System:

 

 

II. Psuedocoelomate Worms: Nematodes

 

Characteristics: 

 

Outer covering:

·         Cuticle

 

Digestion:

 

 

Skeleton: 

 

Movement:

 

Circulation/Respiration:

Nervous System:

 

 

Reproduction:

·         Asexual via parthenogenesis:

 

·         Sexual:

 

Some examples of parasitic nematodes:

 

·         Ascaris (intestinal roundworms)

 

·         Trichinella

 

 

·         Filarial Worms

 

 

 

o   Elephantiasis

 

 

o   River Blindness

 

 

o   Heartworm

 

 

·         Pinworm

 

 

 

·         Hookworm

 

II. Psuedocoelomate worms: other types