vertebrates chapter 34. chordata characteristics
TRANSCRIPT
Vertebrates
Chapter 34
Chordata Characteristics
Invertebrate chordates• Cephalachordata
– Lancelets
• Urochordata– Tunicates, 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– Lamprey– Jawless
• Chondrichthyes– Sharks, rays– Cartilage skeletons
• Osteichthyes– Bony fish– Scales and fins– Most 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 mammals
• Placental Mammals– Bats, shrews– Herbivores, rabbits, cows, whales, elephants– Carnivores: seals and relatives– Primates and rodents