Transcript Pseudocoelomates

Nematoda
Pseudocoelomates
Grade Bilateria
Division Protostomia
Acoelomates
Example:
Platyhelminthes
Pseudocoelomates
Example:
Nematoda
Division Deuterosomia
Eucoelomates
Examples:
Mollusca, Arthropods, Annelida
Examples:
Echinodermata, chordata
Common Characteristics
• Pseudocoel
– Mesoderm muscle lined ectoderm
• Complete digestive tract
• Organs are within pseudocoel
• Syncytial epidermis with non-living cuticle
Coelom
Phylum Nematoda
• Found everywhere
• Use pseudocoel as a hydrostatic skeleton
– Collagen cuticle
– Longitudinal muscles
• Free living and parasites
• Dioecious
Nematode Body Plan
Muscle Structure
• Longitudinal muscles
– Parallel to ventral and dorsal nerve cords
– Muscle cells form processes to associate with
nerve cells
– Muscles act against the hydrostatic skeleton
Muscle/Nerve Structure
Digestion and Metabolism
• Pharynx
– Radial muscles
• Intestine
– Single cell layer with no muscles
– Body movement and ingestion moves food
• Parasitic nematodes often lack complete
aerobic respiration
Nematode Parasites
• Ascaris (roundworms)
– Found in intestine and lung.
• Hookworms
– Attach to intestine and suck blood.
• Trichina worm
– Forms cysts in muscle
– Causes trichinosis
• Pinworms
– Males are haploid, females diploid
– Live in large intestine
• Filarial worms
– Live in lymphatic system
Caenorhabditis elegans
• Extensively using in genetic and animal
development research
• Lineage of each cells is know and documented
• Whole genome is cloned and sequenced
Family Ancylostomidae
• Hookworm
– Ancylostoma duodenale
– Necator americanus
– Ancylostoma caninum
Ancylostoma cutting “teeth”
Necator americanus
Ancylostoma caninum
Male Copulatory Bursa
Ancylostomidae larval forms
Rhbaditiform larva
Filariform larva
*infective form
Ancylostomidae
Family Ascarididae
• Humans
– Ascaris lumbricoides
• Pigs
– Ascaris suum
• Cats
– Toxocara cati
• Dogs
– Toxocara canis
• Cats and Dogs
– Toxocara leonina
Ascaris lumbricoides
Ascaris Egg Development
Toxocara canis
Toxocara in situ
• Visceral organ migrans in intermediate host
(rodent).
• Visceral organ migrans in humans is a dead
end infection.
Toxocara cati
• Adults in intestine
• Heavy infection can cause intestinal
blockage
Toxocara cati
Toxocara cati
Toxocara transmission to young
• Toxocara cati
– transmammary route to kittens.
• Toxocara canis
– transplacental to fetus and transmammary route
to puppies.
Strongyloides sterocoralis
• Homogonic cycle
– Female is parasitic
– Parthenogenesis
• Heterogonic cycle
– Free living worms can mate in soil
Strongyloides stercoralis
Enterobius vermicularis
• Pinworm
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Not very pathogenic only discomfort
Do not infect dogs or cats
Feed on epithelial cells and bacteria in intestine
Males are haploid, females diploid
Enterobius
vermicularis
Male and Female Pinworms
Flat sided pinworm eggs
Dirofilaria immitis
•
•
•
•
Dog and cat heart worm
Transmitted through mosquitoes
Most common in dogs
Infects heart and lungs
Dirofilaria immitis in blood
Dirofilaria immitis in heart
Wuchereria bancrofti
• Causes Elephantitis
• Swelling and blockage of
lymph ducts cause massive
swelling in late stages
Trichinella spp.
• Domestic cycle
– Pigs
• Trichinella spiralis
• Sylvatic cycle (hunting and eating wild mammals)
– Temerate Zone
• Trichinella britovi
• Trichinella spiralis
• Trichinella murrelli
– Tropic Zone
• Trichinella nelsoni
– Arctic Zone
• Trichinella nativa
Trichinella
spiralis
Trichinella spiralis in situ
Muscle
Blood
Phylum Acanthocephala
• Absorb nutrients through tegument
• Infect livestock, dogs and cats
• Requires invertebrate intermediate host
– For example – beetle grubs are the intermediate
host for pig infection
• Proboscis
– Everts and attaches to intestine