Nematoda 

• ”round worms” ex: Ascaris lumbricoides 
•   the second largest phylum in animal kingdom
• inhabit an incredible variety of habitats

 (ocean sediments, land soils, ponds, “vinegar eels” are specially adapted to live in German beermats!)

(many are parasitic & hosts include plants, insects and animals)

 Nematoda 

Body Shape

•  Like a tube within a tube 
•  Have a fluid filled cavity (pseudocoelom) between  digestive tract and cuticle 
•  Cuticle = tough waxy epidermis layer to protect them from the hosts enzymes

Nematoda 

Digestive System

• A mouth which leads to a pharynx which pumps food to the intestine & then out the anus 
• Parasites have less specialization as the host does much of the work for them    
• Nutrients are moved about by diffusion

Nematoda 

Reproduction

• Most species have separate sexes 
• Have extensive ovaries and testes 
• Must copulate to transfer sperm
• Fertilization is internal
•  Problem of finding a mate is overcome by the female attracting mate with pheromon

Nematoda 

Nervous System

• Nerve fibers run the length of the body 
• Have touch and chemo receptors 
• Ganglia-nerve concentrations like a minibrain to control activities in an area

Nematoda 

Other Systems

Excretion : Intestines release nitrogenous wastes into cavity where they pass out through pores in the cuticle

Circulation & Respiration : Gases and etc. move through the cavity by diffusion from areas of high concentration to low conc.

Nematoda 

Parasites

• May include several hosts 
• Fertilized eggs mature in hosts’ intestines & are released in the feces  

Ascaris

Trichina worms-causes trichinosis-from uncooked pork

Filarial worms-causes elephantiasis  

Guinea Worms 

Hook worms-Southern States

Pin Worms