Chordata Characteristics

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Chordata Characteristics
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Invertebrate chordates

• Cephalachordata
• Lancelets
• Urochordata
• Tuniccates, sea slugs
• Vertebrates may have evolved from a sexually
  mature larval urochordate
• Metamorphosis is eliminated
• Leads to vertebrate lifecycle

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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?

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Fishes

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

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Classes of Fish

• Agnatha
• Lamprey, hagfish
• Jawless
• Chondrichthyes
• Sharks, rays
• Cartilage skeletons
• Osteichthyes
• Bony fish
• Scales and fins
• Most efficient swimmers, very numerous

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What possible events led to movement onto land?
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Fossilized and modern coelocanths
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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

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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)

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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

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Aves

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

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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

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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

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Hominidae
Pongidae
Classical Taxonomy
Hominidae
Pongidae
Cladistic Taxonomy
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