Kingdom Animalia

Invertebrates to Vertebrates

General Characteristics

• Multicellular eukaryotes

• Heterotrophs that ingest their food

• Mostly sexual reproduction, some asexual

• Controlled Movement – response via nerve impulses & muscle coordination

Invertebrates vs. vertebrates

•

Evolution

• 800 MYA from motile protists that liked to hang out together

–choanoflagellates

• Movement from water to land– protection from dessication & sun’s

rays

Move from water to land determines changes in…

• Body support & movement• Reproduction • Circulatory system• Respiratory system• Digestive and excretory system• Nervous system

Common morphology

• 3 categories of morphology for classification and evolutionary advances–Symmetry–Germ layers–Body cavity

symmetry

Advantages of bilateral symmetry

– Allow for cephalization• Centralized nervous system in a head

– Allows for segmentation• Specialization of body parts

– Allows for one way digestive system• Input (eating) to output (excretion) that

flows in one direction vs. a 2-way system

Germ layers• Ectoderm

-becomes hair, skin, nervous system • Mesoderm

-becomes skeleton, muscle, inner skin, circulatory system, liver

• Endoderm– becomes gut and associated organs,

lungs, gills, pancreas, and their linings

Body Cavity• Acoelomate

–Solid organism–restricted movement &

function• Psuedocoelomate

–False body cavity

Body Cavity, cont’d

Coelomate– True body cavity – body cavity surrounded by

mesoderm– Allows for ease of mobility & function, i.e.

digestion, circulation– More room for larger organs (or coiled organs)

so processes can take longer/efficiency– Allows for retention of eggs/gametes

• Internal fertilization (protects young)

Patterns of Development

• Type of cleavage determines whether or not cells can regenerate and ease of cloning

Patterns of Development• Indirect

–Metamorphosis through a life cycle

vs.

Direct

-growth & differentiation

Earliest animals - sponges

• Phylum Porifera• Collection of cells, able to

communicate with each other

• No true tissue layers• No symmetry or organs• Sessile, suspension feeders• O&D• regeneration

First true animals

• Phylum Cnidarian– Jellies, anemones, hydra,

corals

• Phylum Ctenophora– Comb jellies– 2 (?) true tissue layers but

lacking in complex systems– Sexual reproduction– Radial Symmetry

Early Worms• Phylum Playthelminthes

– flatworms

• Phylum Nematoda– Round worms

Phylum Mollusca• 1st with true coelum

• The “head-foods”

• Radula

Phylum Annelida

• Earthworms (segmented worms)

• Hermaphrodites

• Do NOT regenerate!!

Phylum Arthropoda• Largest phylum, essential for evo. Of plants

• Exoskeleton limits size– Crayfish, insects, lobsters, spiders

– Jointed appendages

Phylum Echinodermata• First deuterostomes, closely related to us

• Starfish, sea urchins– “Spiny skin”

Phylum Chordata

• Dorsal nerve chord

• Notochord

• Pharyngeal (gill) slits

• Post-anal tail– Classes – birds,

reptiles, amphibians, mammals