4 Defining Characteristics1. Notochord - extends through

length of the body as a simple skeleton

2. Dorsal, hollow nerve cord3. Pharyngeal gill slits4. Muscular postanal tail

Three SubphylumUrochordata

TunicatesCephalochordata

Lancelets

VertebrataFishAmphibiansReptilesBirdsMammals

Tunicates“Tail Cords” – over 2,000 species Adults sessile Free swimming larvae; only larvae have a 4 defining characteristics

SUBPHYLUM UROCHORDATA

Lancelets “Head-Cords”tiny marine animalsretain all 4 characteristics into adulthoodNotochord, pharyngeal slits, dorsal hollow nerve

cord, post anal tail

led to vertebratesFilter Feeders

SUBPHYLUM CEPHALOCHORDATA

SUBPHYLUM VERTEBRATA

5 Classes1st vertebrates, aquaticGenerally characterized by scales, fins and pharyngeal gills

Exothermic (Ectothermic) – no internal body temperature regulation

Fish

Circulationclosed circulatory system with a 2 chambered

heart. Reproduction reproduce through external fertilization -

spawning

Jawless FishHagfish (Class Myxini) and Lampreys

(Cephalaspidomorphi)Lack vertebrae (hagfish) or have incomplete vertebral

column (lamprey)Predators that attach to the side of a fish with

modified mouthHave no scales

Hagfishno vertebraehas a skull

Class ChondrichthyesCartilage fishSharks, skate, rays and

sawfishPrimitive Older fishMost have to swim to

breathe

Bony FishRay finned fish (Class

Actinopterygii ) - - most common fish- have jaws and paired fins- fins supported by rays fanning our from central bone

Lobe finned fish (Class Sarcopterygii)- fins supported by central axis bone- ancestors of amphibians

Walking Fish - Grunion

Class AmphibiaFrogs and salemandersAquatic as larvae, after metamorphosis, live

on land as adults.Have moist skin with many glandsmust be moist to breathe; respirate through

skinevolved from fish 360 myaexothermic

CirculationAmphibians have a double-loop circulatory

system with three-chambered heart.ReproductionFertilization is external Shell-less eggs must be laid and fertilized

in water

Class ReptiliaInclude 3 groups: snakes, turtles, crocodiles Fully adapted to life on land

Amniotic egg scaly skin (prevents loss of moisture) Exothermic - regulate their body temperatures by basking in the sun, burrowing in the ground. Soaking in water etc…

Circulationmore efficient circulatory and respiratory

systems (lungs, 3 chambered heart).Reproduction internal fertilizationLay fluid filled amniotic egg covered with a

protective shell

Class AvesMost are adapted for flightCovered with feathershollow bones2 legs for walking, 2 modified for wings

Birds are endothermic - generate body heat internally by their own metabolism.

Circulation4 chambered heart; allows for efficient

delivery of O2 to cells.Reproduction internal fertilization. incubate eggs and feed young have amniotic eggs (keeps eggs moist)

Fossil evidence shows that birds evolved from the same line as crocodiles and dinosaurs.

Class MammaliaCharacteristics:hair - insulation, camouflage,

sensory device, waterproofing, signaling and defense

mammary glandsEndothermic

Circulation4 Chambered heartRequire a constant supply of

nutrients and oxygen to maintain homeostasis and metabolism

Keeping blood separate makes the delivery of nutrients and oxygen more efficient.

ReproductionInternal fertilization

1. Monotremes - young develop in shelled eggs;

Ex. spiny anteater and duck-billed platypus

2. Marsupial - young leave mother’s body to pouch before development is complete.

Ex. kangaroo and opossum

3. Placental - young develop completely within the uterus of the female

Ex. Human, whales, giraffe etc…

3 Types