1. Phylogeny of Metazoa.- 2. Porifera (Sponges).- 3. Cnidaria (Cnidarians).- 4. Platyhelminthes (Flatworms).- 5. Annelida (Segmented Worms).- 5.1. The Ragworms Hediste sp. and Alitta sp. (Errantia).- 5.2. The Common Earthworm Lumbricus terrestris (Sedentaria).- 6. Mollusca (Mollusks).- 6.1. The Common Pond Mussel Anodonta anatina (Bivalvia).- 6.2. The Roman Snail Helix pomatia and the Garden Snail Helix aspersa (Gastropoda).- 7. Nematoda (Roundworms).- 8. Arthropoda (Arthropods).- 8.1. The European Crayfish Astacus astacus (Crustacea).- 8.2. The Argentine Cockroach Blaptica dubia (Hexapoda).- 9. Echinodermata (Echinoderms).- 9.1. The Common Starfish Asterias rubens (Asteroidea).- 9.2. The Shore Sea Urchin Psammechinus miliaris and the Common Sea Urchin Echinus esculentus (Echinoidea).- 10. Acrania (Cephalochordata) Lancelets.- 11. Chordata, Urochordata (Tunicata, Tunicates).- 12. Craniota (Vertebrata), Craniates or Vertebrates.- 12.1. The Rainbow Trout Oncorhynchus mykiss (Teleostei, Bony Fishes).- 12.2. The Laboratory Rat Rattus norvegicus (Mammalia, Mammals).- Further Reading.