Pseudocoelomates

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Pseudocoelomates

• Rotifera
• Nematoda

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Pseudocoelomates
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Common Characteristics

• Pseudocoel
• Mesoderm muscle lined ectoderm
• Complete digestive tract
• Organs are within pseudocoel
• Syncytial epidermis with non-living cuticle

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Coelom
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Phylum Rotifera

• 1800 species
• Live mainly in fresh water
• Some are marine or terrestrial
• Feed on plankton

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Rotifer Body Plan

• Head
• Corona draw in food
• Mastax grinding jaws
• Trunk
• Cloacal bladder
• Excretion
• Foot
• Pedal glands attachment

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Phylum Nematoda

• Found everywhere
• Use pseudocoel as a hydrostatic skeleton
• Collagen cuticle
• Longitudinal muscles
• Free living and parasites
• Dioecious

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Nematode Body Plan
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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

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Muscle/Nerve Structure
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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

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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

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Caenorhabditis elegans

• Extensively using in genetic and animal
  development research
• Lineage of each cells is know and documented
• Whole genome is cloned and sequenced

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Dirofilaria immitis

• Dog and cat heart worm
• Transmitted through mosquitoes
• Most common in dogs
• Infects heart and lungs

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Brugia malayi

• Causes Elephantitis
• Swelling and blockage of lymph ducts cause
  massive swelling in late stages

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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

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• Proboscis
• Everts and attaches to intestine