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

Pores Ostia –Small 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

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

Radiate Phyla CnidariaCtenophore

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