Digestive system, respiratory All animals have 3 germ layers = TRIPLOBLASTIC Except: sponges, jellyfish, anemones = DIPLOBLASTIC Endoderm Mesoderm Ectoderm Digestive system, respiratory Muscle, excretory, bones, circulatory Outer skin, brain, nervous system

Types of Coeloms (See-Lums) No cavity (space) around organs Image from: http://io.uwinnipeg.ca/~simmons/16labman05/lb5pg10.htm ACOELOM = “without space”

FLATWORMS are ACOELOMATES!

Types of Coeloms (See-Lums) Space around organs but only lined with mesoderm on one side (lines body wall BUT NOT around gut) Image from: http://io.uwinnipeg.ca/~simmons/16labman05/lb5pg10.htm PSEUDOCOELOM

ROUND WORMS are PSEUDOCOELOMATES!

Kinds of Coeloms (See-Lums) EUCOELOM: Body cavity (space) lined on BOTH sides by mesoderm Image from: http://io.uwinnipeg.ca/~simmons/16labman05/lb5pg10.htm EUCOELOM = TRUE COELOM = COELOM

EUCOELOMATES ALL VERTEBRATES & MOST INVERTEBRATES

3 Types of Coeloms ACOELOM EUCOELOM PSEUDOCOELOM ectoderm mesoderm endoderm Image from: http://www.lander.edu/rsfox/310images/310bil5.jpg

FUNCTIONS of having a COELOM (body space): Provides space/cushion internal organs In animals without a skeleton- Fluid in coelom space can act as a HYDROSTATIC skeleton In animals without blood vessels- Fluid in coelom space can circulate nutrients and oxygen to cells

ADVANTAGE OF a EUCOELOM? Digestive organ muscles and body wall muscles come from MESODERM in different places so organism can digest food and move at same time. Images from: http://www.lander.edu/rsfox/310images/310bil5.jpg http://www.okc.cc.ok.us/biologylabs/Images/Animal_Images/coelomate.gif