Vertebrates Chapter 34

Chordata Characteristics

Invertebrate chordates Cephalachordata –LanceletsLancelets Urochordata –Tunicates, sea slugsTunicates, sea slugs Vertebrates may have evolved from a sexually mature larval urochordate Metamorphosis is eliminated Leads to vertebrate lifecycle

Subphylum: Vertebrata Cephalization Vertebrate skeleton Brain protected by skull Closed circulatory system Gills or lungs Kidneys for excretion dioecious How do these characteristics enhance success of vertebrates?

Fishes Very successful vertebrates –Fast streamlined body plan –Excellent sensory organs –Highly developed organs for osmoregulation –Complex behavior –2 chambered heart

Classes of Fish Petromyzontida –LampreyLamprey –JawlessJawless Chondrichthyes –Sharks, raysSharks, rays –Cartilage skeletonsCartilage skeletons Osteichthyes –Bony fishBony fish –Scales and finsScales and fins –Most efficient swimmers, very numerousMost efficient swimmers, very numerous

What possible events led to movement onto land?

Fossilized and modern coelocanths

Life on Land Problems: No support on land Gills stick together Ammmonia no longer a good source of excretory waste Dehydration Sound light smell is perviecved differently on land Solutions cartilage  bone Lungs Excrete concentrated urea  uric acid Skin and scales Adapt ability to perceive sound, smell and light differently

Amphibia Shoulder hip and girdles act to strengthen limbs for life on land Heart with 3 chambers Bladder In what ways are amphibians similar to brypohytes? They are not completely free from water –Reproduction –Dessication (skin must stay moist)

Reptilia Completely free from water Amniote egg Scaly skin 3-4 chambered heart Uric acid as nitrogenous waste In what way are these animals still limited? Ectothermic

Aves Evolved from reptiles Flying dinosaurs Bones and feathers are adapted for flight 4 chambered heart Endothermic Efficient 1 way lungs Excrete uric acid

Mammalia Hair Mammary glands Placenta connects fetus to mom (missing in marsupials) Diaphragm for ventilation of lungs 4 chambered heart Endothermic Large brains Diverged from reptilian ancestors earlier than the birds

Major groups Monotremes: –Platypuses, lay eggs –Mixture of reptilian and mammalian traits Marsupials –Non-placental –Young born early and develop within pouch –Convergent evolution with placental mammalsConvergent evolution with placental mammals Placental Mammals –Bats, shrews –Herbivores, rabbits, cows, whales, elephants –Carnivores: seals and relatives –Primates and rodents