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)

A Cladogram of Chordates Nonvertebrate chordates Jawless fishes Cartilaginous fishes Bony fishes Amphibians Reptiles Birds Mammals

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) Body Temperature (°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)

Digestive Systems of Vertebrates Shark Salamander Lizard Pigeon Cow Esophagus Stomach Intestine Liver Gallbladder Pancreas Cloaca Crop Gizzard Cecum Rectum

Respiratory Systems of Vertebrates Nostrils, mouth, and throat Trachea Lung Air sac Salamander Lizard Primate Pigeon

Single-Loop Circulatory System Double-Loop Circulatory System Circulatory Systems of Vertebrates Single-Loop Circulatory System Double-Loop Circulatory System FISHES MOST REPTILES BIRDS & MAMMALS

Domestic pigeon Right atrium Left atrium Right ventricle Left ventricle Heart Complete division

Section 32-1 Left atrium Right atrium Left ventricle Right ventricle Complete division

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)