• Round worms
• Molting--ecdysozoa
• Soil, fw, marine
• Free living and parasitic

• Cuticle--support and protection
• Pseudocoelum
• Only longitudinal muscle
• Complete digestive system

• Dioecious
• Sexual dimorphism
• Internal fertilization
• Eggs are juvenile adults
• Male--hooked ending

Parasitic nematodes

Ascaris

• Lives in intestine
• 1/4 of world is infected
• Mouth with 3 lips
• Eggs hatch in intestine

Parasitic nematodes

Trichinella

• Pig, rat, human--vectors
• From undercooked pork
• Adults live in intestine
• Eggs migrate to skeletal muscle and encyst
• Deadly with no cure

Parasitic nematodes

Pinworms

• Enterobius--species
• In large intestine
• Eggs near anus, can become airborne
• Common in cities and children

Parasitic nematodes

Hookworms

• Intestine
• Teeth--cutting plates
• Ingest blood--cause anemia
• Causes reduced growth in children
• Dog hookworms cause cutaneous larva migrans

Parasitic nematodes

Filarial worms

• 8 species
• Produce microfilariae
• Elephantasis--mosquito vector, blocks lymphatic vessels 
• River blindness--black fly vector, lives under skin
• Dog heartworm--Dirofilaria, common in US, deadly, mosquito vector