What is the difference between an invertebrate and a

vertebrate animal?

Invertebrates do not have a backbone

• Examples: jellyfish, earthworm, grasshopper, butterfly, octopus, crab

Vertebrates are chordates• Characteristics of chordates (all present at some point

during development) Notochord – flexible, supporting structure. The notochord

becomes the backbone in vertebrate chordates. Dorsal hollow nerve cord (spinal cord) Post-anal tail – a tail that is posterior to the anus Pharyngeal pouches (gill slits)

Nonvertebrate chordates

Jawless fishes

Cartilaginous fishes

Bony fishes

Amphibians

Reptiles

Birds

Mammals

 A Cladogram of Chordates

Evolutionary Patterns

• Adaptive radiation or divergent evolution – evolutionary lines become less similar

• Convergent evolution – unrelated organisms become more similar

Body Temperature Control

• Ectotherms obtain heat from the environment and rely on behavior to regulate body temperature (fish, amphibian, reptile)

• Endotherms generate heat through metabolic activity and rely on physiological mechanisms to regulate body temperature (birds, mammals)

Bo

dy

Tem

per

atu

re (

°C)

Environmental Temperature (°C)

Trends in Vertebrate Evolution• As you move from fish to mammals, organ

systems become more complex• The heads of vertebrates show many adaptations

for feeding (mouthparts, snouts and tongues)

Esophagus

Stomach

Intestine

Liver

Gallbladder

Pancreas

Cloaca

Crop

Gizzard

Cecum

Rectum

Shark Salamander Lizard Pigeon Cow

Digestive Systems of Vertebrates

Salamander Lizard PigeonPrimate

Nostrils, mouth, and throat

Trachea

Lung

Air sac

Respiratory Systems of Vertebrates

Double-Loop Circulatory SystemSingle-LoopCirculatory System

FISHES MOST REPTILES BIRDS &

MAMMALS

Circulatory Systems of Vertebrates

Right atrium

Left atrium

Complete division

Heart

Domestic pigeon

Left ventricle

Right ventricle

Section 32-1

Right atrium

Left atrium

Complete division

Left ventricle

Right ventricle

Excretory Systems

• Fish and aquatic amphibians excrete ammonia through gills

• Birds and reptiles excrete uric acid through kidneys

• Mammals, land amphibians and cartilaginous fish excrete urea through kidneys

Nervous system

• The complexity of the cerebrum and cerebellum increases from fish to mammals

Movement

• Fish, snakes and salamanders move by wiggling side to side; limbs stick out to side

Movement

• Reptiles (lizards, crocodiles) have limbs bent under body, movement still side to side

• Mammals and birds have limbs directly under body; movement involves the backbone flexing up and down

Reproduction

• Sexual

• Fertilization is external in water for fish and amphibians

• Fertilization is internal on land for reptiles, birds and mammals

• Development of the egg is related to the habitat (oviparous, ovoviviparous or viviparous)