Evolution of Animal Diversity Chapter 18 Animal Evolution

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Evolution of Animal Diversity Chapter 18

Evolution of Animal Diversity Chapter 18

Animal Evolution Basics • Animal Evolution was rapid, occurring ~ 600 million years ago

Animal Evolution Basics • Animal Evolution was rapid, occurring ~ 600 million years ago (Precambrian Era) • Evidence suggests that animals have evolved from protists that lived as colonies of cells. • Colonies form when cells divide, but do not separate. • These cells differentiated and became specialized.

Protoanimals • Model of blastula and grastula used to represent these early animals. Sources:

Protoanimals • Model of blastula and grastula used to represent these early animals. Sources: http: //farm 3. static. flickr. com/2372/2121294845_dab 7667079. jpg? v=0 ; http: //www. dkimages. com/discover/previews/800/912525. JPG

Cambrian Explosion (545 mya) • Time period in which all the major body plans

Cambrian Explosion (545 mya) • Time period in which all the major body plans seen today developed. • Occurred during a short, 10 million year period of time. • Why? ? – Ecological (food), Geological (atmosphere), Genetic (reg. genes)

Animal Specs. • Multicellular, eukaryotes that are heterotrophic (utilize ingestion). • Animal cells lack

Animal Specs. • Multicellular, eukaryotes that are heterotrophic (utilize ingestion). • Animal cells lack cell walls, utilize intercellular junctions, proteins. • Utilize muscle cells for movement

Animal Reproduction • Reproduce sexually • Mitosis & Meiosis involved • Blastula -> Grastula

Animal Reproduction • Reproduce sexually • Mitosis & Meiosis involved • Blastula -> Grastula -> Ectoderm (epidermis) -> Endoderm (lines digestive tract) -> Mesoderm (internal organs) • Larval stages & Metamorphosis sometimes present • Hox genes = reg genes that control development.

Invertebrates / Vertebrates • Invertebrates = lack vertebral column • Vertebrates = have vertebral

Invertebrates / Vertebrates • Invertebrates = lack vertebral column • Vertebrates = have vertebral column

Animal Ancestry • Ancient Choanoflagellates = ancestor of all animals species today. – Colonial

Animal Ancestry • Ancient Choanoflagellates = ancestor of all animals species today. – Colonial protist. – Fig. 18. 3 E

Radial Symmetry • Animal body parts are arranged in a pie-like shape (around central

Radial Symmetry • Animal body parts are arranged in a pie-like shape (around central axis). – Ex: Phylum Cnidaria: jellyfish Phylum Porifera: Cylindrical sponges – Fig. 18. 3 B

Sponge Nutrition (Phylum Porifera) • Suspension Feeders = animals that collect food particles from

Sponge Nutrition (Phylum Porifera) • Suspension Feeders = animals that collect food particles from water passed through some type of foodtrapping mechanism. – Choanocytes: Trap and obtain bacteria from water via mucus. – Amoebocytes: digest food packaged in vacuoles. – Package food via phagocytosis (engulfment)

Cnidarians • Have gastrovascular cavity – Incomplete digestion: undigested foods exit through mouth. –

Cnidarians • Have gastrovascular cavity – Incomplete digestion: undigested foods exit through mouth. – Classified as polyp or medusa – Ex: Sea anemones, jellies

Bilateral Symmetry • Animal can be divided equally by a single cut; left &

Bilateral Symmetry • Animal can be divided equally by a single cut; left & right mirror image. • Anterior (Head) - houses brain, sensory organs, and mouth. • Posterior (Tail) • Dorsal (Back) • Ventral (Bottom) • Lateral (Side)

Bilateral Symmetry • Animals with this symmetry are very active and travel headfirst through

Bilateral Symmetry • Animals with this symmetry are very active and travel headfirst through its environment. • Most have complete digestive tract (mouth to anus) & a body cavity between digestive tract and body wall. • *Importance in evolution of animals*

Body Cavity • *Fluid-filled space between the digestive tract and the body wall was

Body Cavity • *Fluid-filled space between the digestive tract and the body wall was important in the evolution of animals* • Pseudocoelom = body cavity not completely lined by tissue derived from mesoderm. • Coelom (“sea-lum”) = body cavity completely lined by tissue derived from mesoderm (complete digestive tract)

Advantages to having a Body Cavity • Flexibility • Allows use of muscles by

Advantages to having a Body Cavity • Flexibility • Allows use of muscles by force derived from “hydroskeleton. ” • Allows internal organs to develop and move independently of outer body wall. • Fluid aids in protecting internal organs. • Circulate nutrients and oxygen. • Aids in waste disposal

Complete Digestive Tract • Anterior portions of body churn and mix food with digestive

Complete Digestive Tract • Anterior portions of body churn and mix food with digestive enzymes. • Posterior portions of body absorb nutrients and dispose of wastes.

Circulatory System • An organ system that distributes nutrients and oxygen throughout the body.

Circulatory System • An organ system that distributes nutrients and oxygen throughout the body.

Segmentation • Subdivision of the body along its length into a series of repeated

Segmentation • Subdivision of the body along its length into a series of repeated parts. • Allows for grouping of specialized cells. • Flexibility = adaptation for movement – Ex: Earthworm - grooved rings (external), coelom partitioned by walls (internal) – Ex: Dragon fly (head, abdomen, & thorax) human (vertebrae & abdominal muscles)

Arthropods • Have an exoskeleton = hard external skeleton. – Consists of layers of

Arthropods • Have an exoskeleton = hard external skeleton. – Consists of layers of protein and chitin (polysaccharide) – Serves as protection and points of attachment for muscles. – Shedding of exoskeleton = molting.

Echinoderms • Endoskeleton - hard internal skeleton.

Echinoderms • Endoskeleton - hard internal skeleton.

Chordates • Have the following features: – Dorsal, hollow nerve chord – Notochord –

Chordates • Have the following features: – Dorsal, hollow nerve chord – Notochord – Pharyngeal slits – Post-anal tail Vertebrate chordates Invertebrate chordates (tunicates & lancelets)

Vertebrates (Chordates) • Have the following features: – Skull & Backbone (encases brain and

Vertebrates (Chordates) • Have the following features: – Skull & Backbone (encases brain and main parts of nervous system) – Endoskeleton (cartilage / hard bone) *Evolution of jaws were of great importance in fish development*

Amphibians • 1 st terrestrial vertebrates • *Evolution of lungs and appendages were major

Amphibians • 1 st terrestrial vertebrates • *Evolution of lungs and appendages were major evolutionary advances in fishes and allowed evolution of amphibians / adaptation to land* • Adapted to living in shallow aquatic habitats and water’s edge. • Proliferated during Carboniferous period.

Reptiles • Adaptations to living on land: – Skin with scales (keratin) – Eggs

Reptiles • Adaptations to living on land: – Skin with scales (keratin) – Eggs that retain water – Amniotic eggs = self-contained nourishment. – Exothermic = absorption of heat externally.

Reptiles • Dinosaurs: – Endothermic animals = use heat generated by metabolism to maintain

Reptiles • Dinosaurs: – Endothermic animals = use heat generated by metabolism to maintain constant body temperature. – Mass extinction ~65 mya – Evolution of Birds

Birds • Relationship to Reptiles: – Presence of amniotic eggs – Scales on legs

Birds • Relationship to Reptiles: – Presence of amniotic eggs – Scales on legs of birds – Toenails of keratin – Similar body structuring to reptiles • Flight Structures: – No teeth, hollow shafted feathers, honeycombed bones (strong, but light)

Birds • High Metabolic Rate • Endothermic (feathers ensure insulation of body temperature) •

Birds • High Metabolic Rate • Endothermic (feathers ensure insulation of body temperature) • Efficient circulatory system

Mammals • Evolved about 220 mya from reptiles. • Mass extinction of dinosaurs allowed

Mammals • Evolved about 220 mya from reptiles. • Mass extinction of dinosaurs allowed for a proliferation of mammals – Exposure to greater resources & lack of predation) • Endothermic, high metabolic rate, presence of hair, and mammary glands.

Mammals • 3 Groups: 1) Monotremes – EX: duck-billed platypus (egg-laying). 2) Marsupials –

Mammals • 3 Groups: 1) Monotremes – EX: duck-billed platypus (egg-laying). 2) Marsupials – EX: kangaroo (External pouch) 3) Eutherians – EX: dogs, cats, humans (Reptile Homologous structure = amniotic tissues)

Mammals • Placenta = structure joining mother & embryo within uterus (#2 & #3)

Mammals • Placenta = structure joining mother & embryo within uterus (#2 & #3) • Placentas provide long-lasting association between mother and developing young.