What kinds of organisms most likely gave rise to the first animals? This cladogram represent the evolutionary relationships among major groups of animals. What kinds of organisms most likely gave rise to the first animals? sponges Which evolved earlier, coelom or bilateral symmetry? Bilateral symmetry Which pair of animals is more closely related; annelids and arthropods or echinoderms and arthropods? Annelids and arthropods

Animal kingdom has 9 phyla: Phylum Porifera sponges Phylum Cnideria jellyfish

Phylum Platyhelminthes Flatworms, tapeworms Phylum Nematoda Roundworms

Phylum Echinodermata Phylum Arthropoda Insects Starfish, sand dollars Spiders

Phylum Chordata ALL vertebrates Humans, dogs, snakes

Animals in the first 8 phyla are invertebrates, which means they DO NOT have a backbone. The only phylum that contains vertebrates (animals with a backbone) is phylum Chordata.

Vertebrates are divided into 5 classes (or groups): Fish- includes jawless fish, sharks and rays Breathe through gills Lay eggs in water Have fins

Amphibians (term means double life)- includes frogs, toads and salamanders Have smooth or bumpy skin Lay eggs in water Gills/lungs Breathe through skin

Reptiles- snakes and turtles Dry, scaly skin Lay terrestrial eggs

Birds- owl, chicken and stork. Have feathers Lay terrestrial eggs

Mammals- human, dolphin, bear, bat and mouse All have fur Feed their young milk