Non-Coelomate Animals

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Non-Coelomate Animals
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Porifera

• Simplest metazoan
• Cell level of organization
• Few cell types
• No true tissues
• Feed on material suspended in water
• Motile as larva - sessile as adult

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Pores

• Ostia
• Small pores
• Water inlets
• Multiple ostia lead to canal system
• Osculum
• Large pores
• Water outlets
• Certain forms have more than one

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Canal Structure
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Four Types of Sponge Cells
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Spicules
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Hexactinellida Glass Sponge
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DemospongiaeLeuconoid Forms
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DemospongiaeLeuconoid Forms
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Radiates

• Radial symmetry
• Tissue level organization
• Two germ layers
• Ectoderm and endoderm
• Nerve net (simple nervous system)
• Extracellular digestion

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Radiate Phyla

• Cnidaria

• Ctenophore

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Phylum Cnidaria

• Two forms
• Polyp
• Medusa
• Tentacles
• Nematocyst

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Polyp and Medusa Forms
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Hydra Tissue Structure
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Obelia Life Cycle
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Zoantharian Coral

• Calcium carbonate exoskeleton secreted externally
  from base
• Contain mutualistic zooxanthallae algae
• Live in colonies
• Hexamerous symmetry

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Medusa
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Hydra
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Sea Anemone
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Soft Corals
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Coral Polyps
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Phylum Ctenophora

• Comb Jellies
• Move using cilia
• Comb plates
• Do not have nematocysts
• Colloblasts capture food

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Predatory Comb Jellies Approaching Prey
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Predatory Comb Jelly Engulfing a Comb Jelly
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Comb Jelly After a Meal
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Acoelomate Phyla

• Platyhelminthes
• Flat worms
• Nemertea
• Ribbon worms
• Gnathostomulida
• Jaw worms

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Why bilateral symmetry?

• Movement toward prey or host
• Cephalization
• Directional sense organs
• Chemoreceptors
• Ocelli (light sensing eyespots)
• Rheoreceptors (sense water currents)

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Acoelomates Key Features

• Three germ layers
• Ectoderm, endoderm, mesoderm
• Mesoderm forms muscle and mesenchyme
• Organ-system level of organization
• Cephalization
• Excretory system
• Some have circulatory and one-way alimentary canal

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Acoelomates Body Plan
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Phylum Platyhelminthes

• Examples
• Planaria freeliving
• Liver Flukes endoparasite
• Tape Worms - endoparasite

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Planaria

• Eye spots (Ocelli)
• Auricles - chemoreceptors

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Liver Fluke Digenetic Life Cycle
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Liver Damage Caused By Flukes

• Scar tissue
• Blocked bile ducts

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Tape Worm Digenetic Life Cycle
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Tapeworm

• New proglottids are added just behind the scolex

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Pseudocoelomates

• Pseudocoel
• Mesoderm muscle lined ectoderm
• Complete digestive tract
• Organs are within pseudocoel

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Coelom
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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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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