Non-Coelomate Animals

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

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

Canal Structure

Four Types of Sponge Cells

Spicules

Hexactinellida – Glass Sponge

Demospongiae Leuconoid Forms

Demospongiae Leuconoid Forms

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

• Cnidaria Radiate Phyla • Ctenophore

Phylum Cnidaria • Two forms – Polyp – Medusa • Tentacles • Nematocyst

Polyp and Medusa Forms

Hydra Tissue Structure

Obelia Life Cycle

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

Medusa

Hydra

Sea Anemone

Soft Corals

Coral Polyps

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

Predatory Comb Jellies Approaching Prey

Predatory Comb Jelly Engulfing a Comb Jelly

Comb Jelly After a Meal

Acoelomate Phyla • Platyhelminthes – Flat worms • Nemertea – Ribbon worms • Gnathostomulida – Jaw worms

Why bilateral symmetry?

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

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

Acoelomates Body Plan

Phylum Platyhelminthes • Examples – Planaria – freeliving – Liver Flukes – endoparasite – Tape Worms - endoparasite

Planaria • Eye spots (Ocelli) • Auricles - chemoreceptors

Liver Fluke – Digenetic Life Cycle

Liver Damage Caused By Flukes • Scar tissue • Blocked bile ducts

Tape Worm – Digenetic Life Cycle

Tapeworm • New proglottids are added just behind the scolex

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

Coelom

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

Nematode Body Plan

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

Dirofilaria immitis

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

Brugia malayi

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