Chapter 34 Notes

Vertebrate Evolution and Diversity

Concept 34.1

Deuterosomes- two main phyla: chordates and echinoderms (sea stars)

Four anatomical features characterize the phylum Chordata- notochord, dorsal nerve chord, pharyngeal slits, and a postanal tail

Concept 34.1

Concept 34.1

There are two subphylums for invertebrate chordates

Urochrodates- aka tunicates- sessile filter feeders; use pharyngeal slits as a siphon

Concept 34.1

Concept 34.1

Cephalochordates- aka lancets- suspension feeders

Concept 34.1

Concept 34.2

Class Agnatha- jawless fish- ex hagfish and lampreys- oval shaped mouth; lack jaws and paired fins- evolution of jaws occurred with modification of supporting structures of gill slits

Concept 34.2

Concept 34.2

Concept 34.4

Advantages of having a jaw- increase range for prey capture- increase size of prey- increased energy content of prey

Allowed jawed species to become larger

Concept 34.4

Concept 34.4

Class Condrichthyes- sharks, skates, and rays- skeleton made of cartilage. Teeth and vertebrae may be strengthened with mineralized granules- very dense; must continue to swim- carnivorous; teeth evolved from scales

Concept 34.4

Concept 34.4

Sexual reproduction w/ internal fertilization-Oviparous: lay egg, then fertilize; embryo develops within egg after laying- Ovoviviparous: fertilized egg develops in mother, but mother and egg are separated; born live after hatching

Concept 34.4

- Viviparous: live young born; embryo develops inside of body; nourished by placenta

Concept 34.4

Class Osteichthyes- ray finned and lobed finned fish- boney fish; endoskeleton w/ calcium phosphate- 2 chambered heart (1 atria, 1 ventricle)- buoyancy maintained w/ swim bladder

Concept 34.4

Concept 34.4

- gills for gas exchange; operculum allow fish to breathe while remaining still- most species are oviparous

Concept 34.4

Concept 34.4

Concept 34.5

Tetrapods: “four feet”- all, except for modified species such as snakes, have four limbs with the same basic structure- used for movement

Concept 34.5

Class Amphibia- means “two lives”- frogs, toads, and salamanders- thought to have evolved from lobed finned fishes- 3 chambered heart (2 atria, 1 ventricle)

Concept 34.5

- most are oviparous; some exhibit other forms- eggs lack a shell and will dehydrate quickly in dry air

Concept 34.5

Concept 34.5

Concept 34.6

Development of the amniotic egg allowed animals to move further away from water

4 parts to the amniotic egg- amnion: prevents dehydration and cushions against shock- yolk sac: stockpile of nutrients for the embryo

Concept 34.6

- allantois: disposal sac for metabolic waste- chorion: allows O2 and CO2 to diffuse freely across the egg’s shell- found in birds, reptiles

Concept 34.6

Concept 34.6

Class Reptilia- scales are made of keratin (waterproof)- 3 chambered heart (2 atria and 1 partially separated ventricle)- nitrogenous waste excreted as uric acid (low water loss)

Concept 34.6

- internal fertilization; most lay an amniotic egg- ectotherms: obtain heat by external absorption; not “cold blooded”

Concept 34.6

Concept 34.6

Class Aves- flightless (ratites) and flight (carinate)- thought to have evolved from dinosaurs- body is designed to enhance flight- endothermic: maintain high body temp through metabolism

Concept 34.6

Why did flight evolve?- to help escape predators- to help catch prey- to help move from place to place- gain access to new food sources

Concept 34.6

Concept 34.6

Adaptations for flight- shortened tails- lack teeth- hollow, thin bones- air sacs- feathers are highly modified scales

Concept 34.6

Concept 34.7

Class MammaliaMonotremes: ex. platypus

-lay eggs- have hair and produce milk

Marsupials: ex. kangaroos, koalas- born early in development

Concept 34.7

Concept 34.7