1. ZOO 115 Invertebrate Zoology
Nematoda

2. Phylum Nematoda Common name: round worms >20,000 species.
Mostly widespread and abundant of all metazoans
90,000 worms in a decomposing apple.
Marine and freshwater benthos, soil, parasites on plants and animals
hooge.developmentalbiology.com/meiofauna/media

3. Phylum Nematoda - Anatomy
/creatures.ifas.ufl.edu/nematode
Nerve cords
Ovaries
Excretory canal
Digestive tract
Most freeliving <2.5 mm in length. Some parasites > 50 cm in length.
Body is cylindrical with a pseudocoel
Complex cuticle
Must molt (Ecdysis)
Anterior end is radially symmetrical but the rest of the body has bilateral symmetry

4. Phylum Nematoda - Head Region Nervous system
Sensilla
/creatures.ifas.ufl.edu/nematode
Sensilla
Chemosensory
Males also have them near the anus
Brain
Ring-like brain
/creatures.ifas.ufl.edu/nematode
Dorsal, ventral and lateral nerve cords

5. Phylum Nematoda - Head Region
/creatures.ifas.ufl.edu/nematode
3 to 6 lips
3-6 lips at the mouth
Muscular pharynx
Pharynx
/creatures.ifas.ufl.edu/nematode
Buccal Cavity varies depending on prey
Bacteria - no teeth or stylet
Plant root - stylet
Carnivore - small teeth and sometimes stylet
Intestine - large hook-like teeth
Stylet - like a
Hypodermic
needle
Buccal Cavity

6. Phylum Nematoda - Digestive tract
Hindgut - Rectum
Rectum
Anus
Foregut (buccal cavity and pharynx shown earlier)
/creatures.ifas.ufl.edu/nematode
/creatures.ifas.ufl.edu/nematode
/creatures.ifas.ufl.edu/nematode
Midgut -Intestine
Intestine
Cuticle

7. Phylum Nematoda – Excretion
Nerve cords
Ovaries
Excretory canal
Digestive tract
Longitudinal
Muscles
Excretory glands and canals thought to be involved in:
Osmoregulation
Ionic regulation
Excretion of waste metabolites
Ammonia secreted through body wall

8. Phylum Nematoda – Musculature
Nerve cords
Ovaries
Excretory canal
Digestive tract
Longitudinal
Muscles
Longitudinal muscles only!

9. Phylum Nematoda - Reproduction
creatures.ifas.ufl.edu/nematode/
Separate sexes - usually
Males have hook-like posterior
Testis
Male Rectum - Cloaca
Reproduction
Digestive waste
Spicule for sperm transfer
Retractable
Spicule
Testis
Rectum - Cloaca

10. Phylum Nematoda - Reproduction
creatures.ifas.ufl.edu/nematode/
creatures.ifas.ufl.edu/nematode/
Females
Ovaries
Eggs
Vulva
Seminal Receptacle
Ovary
Seminal recepticle
Vulva
Eggs

11. Phylum Nematoda - Parasites: Roundworm Life Cycles
Racoon parasite
Baylisacaris procyonis
Plant parasite
Human Parasite
Ascaris lumbricoides

12. Phylum Nematoda - Parasites: Hookworm

13. Phylum Nematoda - Parasites: Trichinella

14. Phylum Nematoda - Parasites: Filariasis