Animal Diversity

Three domains

archaea, bacteria, eukarya

Heterotrophs

must derive foods from other sources to survive

Invertebrate

animals that lack a backbone

Linnaean hierarchy

Kingdom, Phylum, Class, Order, Family, Genus, Species 

Phylogenetic tree

depicts the presumed evolutionary relationships among a group of organisms

Body symmetry

• None (asymmetrical)

• Radial

• Bilateral

Cellular organization

• Collection of cells

• Distinct tissues, organs, or organ systems

Body segmentation

• No segmentation

• Segmentation: repeated units (Arthropods)

Cephalization

• No cephalization: nerve net

• Cephalization: mouth, eye spots, eyes, brain or antennae

Digestive tract

• Incomplete: single opening for eating and pooping

• Complete: two openings, a mouth and anus

Appendages

• No jointed appendages

• Jointed appendages (Arthropods)

Skeleton (body support system)

• Hydrostatic: body fluid structural fibers that contract

• Endoskeletons: calcium-based internal frameworks

• Exoskeleton: external coverings that give the body shape and protect vital organs

Dichotomous key

constructed from a series of couplets or mutually exclusive choices

Invertebrate phyla - Porifera

• Most primitive phylum: lack of energy (no tissues, no digestive tract, no cephalization, etc.)

• Example: sponge

Invertebrate phyla - Cnidaria  

• Two forms 

  • Medusa form is free-swimming

  • Polyp form tends to be sessile

• Example: corals, jellyfish

Nematocysts

• Adaptation of Cnidaria

• Harpoon-like structures, when triggered, deliver toxins that can paralyze prey or deter predators

Invertebrate phyla - Platyhelminthes  

• Parasitic and free-living dorso0ventrally flattened worms

• Have primitive eyes

• Example: planaria, tapeworms

Invertebrate phyla - Mollusca  

• 3 major classes - Bivalves, Gastropods, Cephalopods

• Have a shell (inter

Invertebrate phyla - Arthropoda

• Most diverse and successful phylum

• Example: crayfish

Invertebrate phyla - Echinodermata

• Evolutionarily closest phylum to vertebrates (humans)

• Example: sea stars