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The ChordatesThe Chordates
Chapters 30-32Chapters 30-32
BiologyBiology – Miller – Miller • Levine• Levine
ChordatesChordates
• Phylum Phylum ChordataChordata
• Includes two Includes two invertebrate invertebrate subphyla: subphyla: lanceletslancelets and and tunicatestunicates
• Subphylum Subphylum VertebrataVertebrata
Chordate CharacteristicsChordate Characteristics
• Dorsal, hollow nerve cordDorsal, hollow nerve cord – the – the brain and spinal cord brain and spinal cord
• NotochordNotochord – flexible, longitudinal rod – flexible, longitudinal rod located between the digestive tract located between the digestive tract and the nerve cord and the nerve cord
• Pharyngeal pouchesPharyngeal pouches – gill – gill structures in the pharynx structures in the pharynx
• PostPost--anal tailanal tail – tail to the rear of the – tail to the rear of the anus anus
Chordate CharacteristicsChordate Characteristics
• The characteristics are not always The characteristics are not always visible in the adult form, but are visible in the adult form, but are always present in the embryo always present in the embryo
VertebratesVertebrates
•Subphylum that includes Subphylum that includes mammals, birds, reptiles, mammals, birds, reptiles, amphibians and the various amphibians and the various classes of fishes classes of fishes
•Unique features include cranium Unique features include cranium and backboneand backbone
FishesFishes
AgnathansAgnathans• Jawless fishJawless fish
• ClassClass Myxini Myxini (hagfishes)(hagfishes)
• Class Class CephalaspidomorphiCephalaspidomorphi (lampreys)(lampreys)
Class ChondrichthyesClass Chondrichthyes
•Cartilaginous fishesCartilaginous fishes
• Include sharks and raysInclude sharks and rays
•Have a flexible skeleton made of Have a flexible skeleton made of cartilage cartilage
•Lateral line systemLateral line system – row of – row of sensory organs running along sensory organs running along each side of the body, detects each side of the body, detects minor vibrations minor vibrations
Class ChondrichthyesClass Chondrichthyes
Class OsteichthyesClass Osteichthyes
•Bony fishes (trout and goldfish) Bony fishes (trout and goldfish)
•Also have a lateral line system Also have a lateral line system
•OperculumOperculum – protective flap – protective flap that covers the gills that covers the gills
•Swim bladderSwim bladder – gas-filled sac – gas-filled sac that keeps them buoyantthat keeps them buoyant
Class OsteichthyesClass Osteichthyes• Most are Most are ray-finned fishesray-finned fishes – fins – fins
supported by thin, flexible rays supported by thin, flexible rays • LungfishesLungfishes – must surface to gulp air – must surface to gulp air
into their lungs into their lungs • LobeLobe--finned fishesfinned fishes – fins are – fins are
supported by stout bonessupported by stout bones
AmphibiansAmphibians
Class AmphibiaClass Amphibia
•Frogs and salamandersFrogs and salamanders
•Exhibit a mixture of aquatic & Exhibit a mixture of aquatic & terrestrial adaptations terrestrial adaptations
•Need water to reproduce Need water to reproduce
•Depend on their moist skin to Depend on their moist skin to supplement lung function in supplement lung function in exchanging gases exchanging gases
Class AmphibiaClass Amphibia
• First vertebrates to colonize land First vertebrates to colonize land
• TetrapodsTetrapods (“four legs”) – terrestrial (“four legs”) – terrestrial vertebrates (amphibians, reptiles, vertebrates (amphibians, reptiles, birds & mammals) birds & mammals)
ReptilesReptiles
Class ReptiliaClass Reptilia•Snakes, lizards, turtles, crocodiles, Snakes, lizards, turtles, crocodiles,
and alligatorsand alligators
•Have many additional adaptations Have many additional adaptations for living on land for living on land
•Water-proofed scales to prevent Water-proofed scales to prevent dehydration dehydration
•Amniotic eggAmniotic egg – water-containing – water-containing egg enclosed in a shellegg enclosed in a shell
Class ReptiliaClass Reptilia• EctothermsEctotherms – warms itself by – warms itself by
absorbing external heatabsorbing external heat – Can survive on less than 10% of the Can survive on less than 10% of the
calories required by mammals calories required by mammals
• Mesozoic era – “age of reptiles” – the Mesozoic era – “age of reptiles” – the time of the dinosaurstime of the dinosaurs
BirdsBirds
Class AvesClass Aves
•BirdsBirds•Reptilian Reptilian
features – features – scales on legs, scales on legs, amniotic egg amniotic egg
•Almost all Almost all species are species are able to fly able to fly
Class AvesClass Aves
•Adaptations for flight:Adaptations for flight:– Light, hollow bone Light, hollow bone – Absence of some internal organs Absence of some internal organs – Are toothless Are toothless – EndothermsEndotherms – maintain – maintain
temperature using metabolic heat temperature using metabolic heat – Wings – strong muscles, feathers Wings – strong muscles, feathers
MammalsMammals
Class MammaliaClass Mammalia
•Probably evolved from reptilesProbably evolved from reptiles•Most are terrestrial, some are Most are terrestrial, some are
aquatic (dolphins, whales), some aquatic (dolphins, whales), some can fly (bats) can fly (bats)
•Two unique features: hair and Two unique features: hair and mammary glands mammary glands
•Are endotherms Are endotherms •Have a fluid filled amniotic sacHave a fluid filled amniotic sac
Three Major GroupsThree Major Groups
• MonotremesMonotremes – egg-laying mammals – egg-laying mammals (platypus) (platypus)
• MarsupialsMarsupials – pouched mammals – pouched mammals (kangaroo) (kangaroo)
• EutheriansEutherians – placental mammals – placental mammals– Make up almost 95% of mammalsMake up almost 95% of mammals
• Marsupials and Eutherians both have a Marsupials and Eutherians both have a placentaplacenta which joins the embryo to the which joins the embryo to the mother and provides nutrients to the mother and provides nutrients to the embryo embryo
Class MammaliaClass Mammalia
PrimatesPrimates
•Order that includes monkeys, apes Order that includes monkeys, apes & humans & humans
•Early primates were small, Early primates were small, arboreal (tree-dwelling) mammalsarboreal (tree-dwelling) mammals – Limber shoulder joints, dexterous Limber shoulder joints, dexterous
hands, eyes close together on face, hands, eyes close together on face, excellent hand-eye coordinationexcellent hand-eye coordination
PrimatesPrimates• Divided into two main groups: Divided into two main groups:
– ProsimiansProsimians (lemurs) (lemurs) – AnthropoidsAnthropoids (monkeys, apes & humans) (monkeys, apes & humans)
• Humans are most closely related to apes Humans are most closely related to apes