### Understanding Invertebrates and Vertebrates: Symmetry, Traits, and Evolution ###

1. DOR: Invertebrates • What type of symmetry does a sponge have? • A jellyfish represents an animal from what phylum? • Which phylum contains animals that have an eyespot sensitive to light? • Name one type of parasitic flatworm. • Name 2 unique facts about the circulatory system in Annelids different from other invertebrates.

2. Vertebrates ! ! Moving on up….

3. Phylum: Chordates • Traits: • 1) Notochord • Located on the dorsal (“back” side) of the animal • Structural support, vertebral column develops form this structure • 2) Dorsal tubular nerve cord • Nerve cord for developing embrygo • Becomes brain, spinal cord (vertebrates) • 3) Pharyngeal pouches • “temporary” gill slits from most unless fish, amphibian,and nonvertebrate chordates • 4) Postanal tail • Embryonic tail, may not be observed in adult form.

5. Chordates: Nonvertebrates • Cephalochordates • Ex. Lancelets • Contain all traits of chordates even through adulthood • Provide model for evolutionary and comparative anatomy research • Shallow water, filter feeders • Urochordates • Ex. Sea squirt • Mobile larvae, adult is non-motile/sessile • Does not keep chordate traits to adulthood, only gill slits • Larvae has all chordate traits, bilateral symmetry • Related to vertebrates ?

6. Vertebrates • Contain traits of chordates AND: • 1) Vertebral column • Notochord becomes individual vertebrae • 2) Skull • Brain protection, skeleton includes this structure with vertebral column • Brain develops specialized region, becomes more complex • 3) Endoskeleton • Animal’s internal skeleton, continual growth (bone marrow) • Made of cartilage/bone • Functions: structural, organ protection, muscle attachment • 4) Internal organs • Well-developed digestive tract, closed circulatory system, respiratory system (gills/lungs), and excretory system

8. Vertebrates: Fish • Jawless • Ostracoderms: extinct, no fins, filter-feeders • Agnathans: present, skeleton made of cartilage, notochord present, no scales, cyclinder shape (ex. Lampreys, hagfish)

9. Vertebrates: Fish (cont.) 2) Jawed • Traits: ectotherms (temperature based on environment), gills, closed circulatory system, skeleton with bone or cartilage, SCALES • A) Cartilage • Skeleton composition: cartilage • Dermal denticles—small, rough scales projecting out from animal (ex. Sandpaper) • Ex. Sharks, rays, skates • B) Bony • Ray-finned: most fish, fins have fan shape, variety of feeding styles, SWIM BLADDER • Lobe-finned: fins resemble limbs, can also contain lungs with gills (lungfish), prefer stagnant water

11. Amphibian Evolution • Evolved from early, jawed fish • Ancient lobe-finned fish adapted to live on land via food resources/predation or advantages • Developed into tetrapods (vertebrates with four limbs, terrestrial)

12. Vertebrates: Amphibians • Traits: • Tetrapods, contain limbs • No scales, MOIST SKIN • Lungs—small, aided by moist skin • Closed circulatory system with 3-CHAMBER HEART, DOUBLE LOOP • Sensory system with special tongue and eyelids • Dependent on environment’s temperature (ecotherms) • FERTILIZATION in AQUATIC environment, with metamorphosis • Types: • 1) Salamanders/newts—internal fertilization • 2) Frogs/toads • 3) caeilians—no limbs, resemble worms

14. Vertebrates: Reptiles • Traits: • Limbs occur in pairs—5 toes • THICK/DRY SKIN for water conservation • Lungs well developed • Closed circulatory system with PARTIAL or COMPLETE division of ventricles in heart, DOUBLE LOOP • URIC ACID excretion—water conservation • Ecotherms • AMNIOTIC EGG ! ! ! • Organized based on skull anatomy, no common ancestor (p. 558-559, Fig. 29.15) • Types: • 1) Dinosaurs (ex. T. rex) • 2) Turtles (ex. Box turtle, loggerhead turtle) • 3) Lizards (ex. iguanas, chameleons) • 4) Snakes—Jacobson’s organ, loose jaw attachment to skull (ex. Copperheads, King snake, cottonmouth) • 5) tuatara—pineal eye under skin, resemble lizards • 6) crocodiles/alligators

16. Reptilian Amniotic Egg • Internal fertilization • Contains protective membranes that fuel embryo’s development via nutrients, oxygen, waste elimination, blood. • Amnion– “fluid sac” where embryo resides and develops until hatching

18. Vertebrates: “Modified” Reptiles--Birds • HUGE diversity (flying, flightless, beak/behavior/habitat/foot) • Are considered reptiles so have all the traits of reptiles—closely related to crocodiles • Anatomy is built for flight: • Feathers– warmth/insulation, flight and steering, similar to scales • Strong skeleton • Specialized respiratory—lungs have posterior/anterior air sacs, constant gas exchange, aid in body/bone weigh reduction • ENDOTHERMS—regulate their own body temperature • Highly developed sensory system—brain, sight, reflexes, behavior

20. Vertebrates: Mammals • Traits: • HAIR: isolation, decorative, camouflage • MAMMARY GLANDS: milk production for offspring, female can feed offspring easily without leaving. • Skeleton: BIG brain, differentiation of vertebrae along vertebral column • Closed circulatory, DOUBLE LOOP, 4-CHAMBER HEART • Well-developed nervous system, refined behavior • Offspring develop internally • Types: • 1) Monotremes– contain cloaca, AMNIOTIC EGG (ex. Anteaters, duckbill platypus • 2) Marsupials– “true uterus,” offspring born in uterus and crawl into pouch for continual development (ex. Opossums, koalas, kangaroos) • 3) Placental– main mammal group, offspring develops in uterus, placenta, offspring dependent on parent when born—brain development

22. Homework • Pp. 568-569, #1-15 “Testing Yourself” • Read Chapter 30