Animal Evolution: Chordate and Vertebrate Evolution and Diversity (Learning Outline)

1. Distinguishing features of the phylum Chordata and

representative organisms. 2. Highlights of evolutionary steps of aquatic chordates

and vertebrate animals 3. Highlights of evolutionary steps of land vertebrates. 4. Place chordates in order of appearance on earth. 5. For organisms covered in class or lab, place each in

its classification grouping , relation to others, and know their major evolutionary features.

Sac Body Plan

Tube within Tube

Organ Systems (Coelom)

Level of Organization Multicellular

Segmentation

Spon

ges

Cni

daria

ns

Flat

wor

ms

Rou

nd w

orm

s

Mol

lusc

s

Anne

lids

Radial Symmetry Bilateral Symmetry

No Body Cavity (No coelom)

Body Cavity (Pseudocoelom)

Mouth from First Embryonic

Opening

Mouth from Second Embryonic

Opening

Arth

ropo

ds

Echi

node

rms

Cho

rdat

es

Phyla

Phylum Chordata, is distinguished by four features

• A dorsal hollow nerve cord • A stiff notochord* • Pharyngeal slits • A muscular post-anal tail

Includes invertebrates and vertebrates

(*) A long flexible rod of cells that supports the body of chordates and vertebrate embryos and is in effect a primitive backbone

Chordates Craniates

Vertebrates Jawed vertebrates

Tetrapods Amniotes

Milk

Amniotic egg

Legs

Lobed fins

Lungs or lung derivatives

Jaws

Vertebral column

Head

Brain

Ancestral chordate

Tuni

cate

s

Lanc

elet

s

Hag

fishe

s

Lam

prey

s

Shar

ks, r

ays

Ray

-finn

ed fi

shes

Lobe

-fins

Amph

ibia

ns

Rep

tiles

Mam

mal

s

Chordates Invertebrates

Tunicates - Sea Squirts • Fossil record- appeared in early Cambrian

Period • Marine invertebrates with pharyngeal slits for

suspension feeding

http://www.youtube.com/watch?v=n8ARUKWPJAE

Excurrent siphon

Adult (about 3 cm high)

Mouth

Pharyngeal slits

Dorsal, hollow nerve cord

Larva

Lancelets • Small eel-like organisms that live in the ocean • Filter feeders and use cilia to filter food out of the

water. • Anchor their tails in the sand and let the water wash

over their mouths. • Have a nerve cord, brain but no vertebrae

• http://www.youtube.com/watch?v=GPnPXsanclY

Head

Mouth

Pharynx Pharyngeal slits Digestive tract

Water exit

Segmental muscles Anus

Post-anal tail

Dorsal, hollow nerve cord

Notochord

Jawless fish- Lamprey • Vertebrates • Adult has toothed, funnel-like sucking mouth • No jaws • No paired fins • Skeleton made of cartilage http://www.youtube.com/watch?v=9JQ6oHjpeqU

Sharks and Rays • Jaws • Flexible skeleton made of car tilage • Paired fins • Uncovered gills • Internal fertilization

Bony fishes: sub groups • ray-finned fishes • lobe-finned fishes

Bony Fishes- ray-finned fishes (most fish) - Skeleton reinforced with a hard matrix of

calcium phosphate - Operculi that move water over the gills - A buoyant air-filled swim bladder

Gills

Bony skeleton Dorsal fin

Anal fin Swim bladder

Heart Pectoral fin Operculum

Pelvic fin

Rainbow trout, a ray-fin

• Eels are bony fish that have a muscular, snake-like body

Bony Fishes- Lobe-finned fishes • Muscular fins supported by bones

Tetrapod

Amphibians • Tetrapods—two pairs of limbs allowing

movement on land • Most reproduce in water • External Fertilization and embryos and larval

development take place in water • Examples: Salamanders, frogs and toads

Amniotes • Tetrapod vertebrates • Adapted to survive in a terrestrial

environment. • Internal fertilization • Have an amnion during the embryologic

stage • Egg-laying reptiles and birds and some

early mammals • Internal gestation and milk (Mammals)

Reptiles are amniotes—tetrapods with a terrestrially adapted egg

Terrestrial adaptations of reptiles include Waterproof scales Internal fertilization shelled, amniotic egg

Dinosaurs, the most diverse reptiles to inhabit land – Some of the largest animals ever to inhabit land – May have been endothermic, producing their own body

heat – Living reptiles other than birds are ectothermic

Birds • wings, feathers, and endothermic metabolism • flight adaptations • Evolved from a small, two-legged ectothermic dinosaurs.

Wing claw (like dinosaur) Teeth

(like dinosaur)

Feathers Long tail with many vertebrae (like dinosaur)

Mammals are endothermic amniotes with - Hair for temperature insulation - Internal fertilization - Mammary glands for milk production

Two groups of mammals 1. Marsupials- Kangaroos 2. Eutherians, placental mammals

The embryos of marsupials are: - nurtured within the uterus - leave the uterus before completing development - complete development attached to the mother’s nipple, usually inside a pouch Kangaroo Birth https://www.youtube.com/watch?v=PmJkn9dJDQ8

Eutherians, placental mammals, complete development before birth

Birth of an elephant https://www.youtube.com/watch?v=1IDRIdE05ko