Introduction to Animal Diversity !

and more animal diversity!

Make a hypothesis: How are these 9 animal phyla related Make a hypothesis: How are these 9 animal phyla related? Draw an evolutionary tree with 9 branches… Arthropods (insects, spiders, crustaceans) Nematodes (roundworms) Annelids (segmented worms) Chordates (mostly vertebrates) Platyhelminthes (flatworms) Porifera (sponges) Mollusks (snails to squids) Echinoderms (sea stars, sea urchins) Cnidaria (jellies)

What do all animals have in common? Eukaryotic & multicellular with no cell walls Heterotrophs that ingest food Specialized cells capable of movement

Symmetry in Animals Bilateral Radial

Many bilaterally symmetrical animals show cephalization - a concentration of senses and brain in the head region

Animal Body Plans True digestive system Gastrovascular cavity performs dual functions of digestion and gas exchange

Protostomes vs. Deuterostomes (which comes first, mouth or anus?)

Tissue Organization Tissue - a collection of specialized cells with a common structure and function - separated from other tissues by a membraneous layer - Ex: muscle tissue, nervous tissue - most (but not all!) animals have specialized tissue layers

Tissue Layers Form during embryological development (gastrulation) Blastula (ball of cells) develops germ layers Ectoderm - Endoderm - Mesoderm Embryos with two layers (ecto and endo only) are diploblastic Embryos with all three layers are triploblastic

Diploblast Triploblast Ectoderm Endoderm Mesoderm

Some triploblastic animals have a coelom – a hollow cavity lined with mesoderm tissue that contains internal organs

Segmentation Segment - a distinct section of the body; may be repeating (annelids) or differentiated (arthropods)

Skeletons Endo Exo Hydrostatic