Biology 172

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Biology 172

• Chapter 34
• Phylum Chordata

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Kingdom AnimaliaPhylum Chordata

• Subphylum Urochordata
• Subphylum Cephalochordata
• Subphylum Vertebrata

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Kingdom AnimaliaPhylum Chordata

• Dorsal Hollow Nerve Cord
• Derived from neural tube, from dorsal ectoderm
• Unique to Chordates
• Notochord
• Longitudinal, flexible supporting rod
• Large fluid filled cells, enclosed in Stiff
  fibrous tissue

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Kingdom AnimaliaPhylum Chordata

• Pharyngeal Clefts
• Allows water to pass through slits
• Function in suspension feeding
• Later adapted to gas exchange
• Muscular Postanal Tail
• Contains skeletal elements and muscle
• Segmented Muscles - Somites

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Chordate Characteristics
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Subphylum Urochordata Tunicates and Larvaceans
-2500 species -Sessile marine animals,
Tadpole-like larva -Pharynx enlarged into a
pharyngeal basket -Water enters incurrent siphon,
passes through pharyngeal slits, to atrial
cavity, excurrent siphon -Atrial cavity
surrounded by a cellulose-like tunic -Related to
Chordate ancestry -Filter feeder, using a mucus
net
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Tunicates orSea Squirts
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Figure 33.x2 Salp chain
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Subphylum Cephalochordata Lancelets
-Fish like, retain all chordate
characteristics as adults -Only a few cm in
length - Live buried in soft marine sediments
-Filter feeders, mucus net around around
pharyngeal slits - Chevron shaped serially
arranged muscles, somites
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Subphylum Cephalochordata Lancelets
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Craniate Divergence

• Two Sets of Hox Genes vs. One
• Neural Crest
• Teeth, Bone/Cartilage, Facial Dermis,
  Neurons, Sensory Capsules
• Skeletal elements
• Pharyngeal Clefts
• Carnium and vertebral column
• Closed Circulatory system 2 Chambers
• Kidneys

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Neural Crest
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Primitive Craniates
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Class Myxini - Hagfish

• Hagfishes Scavengers
• Feed on dead of dieing fish or worms
• Slime glands
• Cranium Thus Craniata
• Notocord, no vertebra
• Only Craniate that is a true osmoconformer.

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Hagfish
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Evolution of Vertebrates

• Gene Duplication in Dlx Family
• Transcription Factor Genes
• Innovations in Nervous and Skeletal System
• More Extensive Skull
• Vertebra Simple to Complex
• Dorsal, Ventral and Anal Fins with Rays
• More Efficient Gas Exchange in Gills
• First vertebrates 500 mya

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Early Vertebrates

• Conodonts Barber hooks mineralized dental
  tissue.
• No paired fins
• Abundant for 300 million years
• Ostracoderms Very Diverse
• Still Jawless

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Early Vertebrates
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Subphylum Vertebrata
Class Cephalaspidomorphi Lampreys

• Jawless
• Lamprey Blood Sucking Parasit
• Scaleless
• Lacking Paired Appendages
• Suspension Feeding Larva in Lamprey

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Class CephalaspidomorphiLampreys

• Cartilage Skeleton but no Collagen
• Retain Notochord enveloped with cartilage
  pipe.
• Paired Cartilage Projections from Pipe
• Cranium and Primitive vertebra
• Partially enclosed dorsal nerve cord
• Life Cycle

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Lamprey
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Superclass GnathostomataThe Fishes

• Jaws from anterior pharyngeal slits
• Duplication of Hox genes for four sets
• Other gene clusters
• Enlarged forebrain Vision and Smell
• Lateral Line
• Ancestors Show Mineralization of the
• Endoskeleton
• Paired Appendages

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Fossil Gnathostomes

• 470 mya
• Adaptations for Success
• Paired Fins and Tail Fin
• Jaws
• Placoderms - Armored
• Acanthodians Fresh Water and Marine
• Related to Bony Fishes

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Superclass GnathostomataThe Fishes

• Class Chondrichthyes Cartilage
• Skeleton Sharks, Skates, Rays
• Osteichthyes The bony fish
• Class Actinopterygii Bony Ray-finned
• fish
• Class Actinistia Lobe-finned fish
• Class Dipnoi Lung fish

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Origin of Jaws
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Subphylum Vertebrata
Class Chondrichthyes Sharks, Skates, and Rays

• 750 Species
• Cartilaginous Skeleton
• Asymmetrical Caudal Fin
• Placoid Scales
• Teeth
• Two Chambered Heart
• Electroreceptors, hearing,
• chemoreception, sight

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Class Chondrichthyes Sharks, Skates, and Rays

• Lateral Line Present
• Water Pressure and Vibrations
• Spiral Valve Increases Surface Area
• Most are Continuous Swimmers
• No Swim Bladder
• Buoyancy Provided by Oil
• Oviparous, ovoviviparous, viviparous

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Class Chondrichthyes Sharks, Skates, and Rays
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Superclass GnathostomataOsteichthyes Bony Fish

• 30,000 species
• Ossification
• 3 Classes
• Flattened bony scales
• Mucus glands
• Lateral line
• Operculum
• Swim Bladder
• Maneuverable
• Devonian and Carboniferous Diversification

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Subphylum Vertebrata
Class Actinopterygii Ray-finned Fish

• 30,000 Species, Most Diverse
• Freshwater and Marine
• Bony Skeleton
• Swim Bladder
• Operculum
• Fresh Water Origin

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Class Actinopterygii

• Scales, Skin Glands
• Lateral Line
• Two Chambered Heart
• Most oviparous with external
• fertilization
• Some ovoviviparous or viviparous with internal
  fertilization

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Class Actinopterygii Bony Fish
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Class Actinopterygii Bony Fish

• Trout

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Class ActinistiaLobe-finned Fishes

• Fleshy, Muscular Fins, With Well Developed
  Bones
• Paired Fins Used to Walk on Bottom
• Modern Molecular Evidence Suggest That Other
  Lung Fishes May Have Given Rise to Amphibians.
• Only Extant Species is Marine with no Lungs
• Coelocanth

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Coelocanth
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Class DipnoiLung Fishes

• Second line of lobe-finned fishes
• Lungs connected to pharynx
• Southern hemisphere today
• A third line of lobe-finned fishes
• gave rise to tetrapods.
• Gave rise to terrestrial vertebrates
• Tetrapods from specialized fish

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Figure 34.15 The origin of tetrapods
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Figure 34.16 Skeleton of Acanthostega, a
Devonian tetrapod fish
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Subphylum Vertebrata
Class Amphibia Frogs, Toads, Salamanders

• Early Amphibians Up to 4m
• Appeared 365 Million Years Ago
• Started Declining 245 mya
• 4,800 Extant Species
• H2O Needed for Reproduction

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Class Amphibia Frogs, Toads, Salamanders

• No External Ears
• Tympanic Membrane
• Smooth Skin
• Poikilothermic/Ectothermic
• External Fertilization
• Three Chambered Heart
• Undergo Metamorphosis

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Orders of Amphibia

• Order Anura - Frogs, Toads
• Order Urodela - Salamanders
• Order Apoda - Legless

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Class Amphibia Frogs,
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Class AmphibiaSalamanders
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Frog Life Cycle
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The Amniotes

• The Amniotic Egg
• Extraembryonic Membranes
• Chorion
• Allantois
• Yolk sac
• Amnion Amnionic fluid
• Waterproof skin
• Rib ventilation

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Amniotic Egg
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Subphylum Vertebrata
Class Reptilia Snakes, Lizards, Geckos,
Skinks Turtles, Crocodilians and Birds

• Amniotic Egg
• Scales
• Oviparous or Ovoviviparous
• Produce Uric Acid
• Generally Carnivores
• Three Chambered Heart in Most

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Class Reptilia Snakes, Lizards, Geckos,
Skinks Turtles, and Crocodilians

• Well Developed Lungs
• Ectotherms
• Poikilothermic/Exothermic
• Aposematic Coloration
• Use Less that 10 of Calories of mammals

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Dinosaurs

• Dinosaurs and Pterosaurs
• Many Varieties
• Cretaceous Extinction

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Class Reptilia - Snakes

• Loosely Jointed Jaws
• Jacobsons Organs
• Vestigial Pelvic and Limb Bones in some
• Pit Vipers
• Toxins

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Snakes
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Class Reptilia Snakes, Lizards, Geckos,
Skinks Turtles, and Crocodilians
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Subphylum Vertebrata
Class Reptilia Birds

• 8,600 Extant Species
• Honeycombed Bones
• Some Organ Systems Reduced
• No Teeth, Keratin Bill
• Efficient Circulatory and Respiratory System

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Class Reptilia Birds

• Homeothermic/Endothermic
• Often show Sexual Dimorphism
• Four Chambered Heart
• Fused Bones in Wings
• Large Sternum Flight Muscles
• Feathers - Keratin
• Air Sacs
• Scaled Legs

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Archaeopteryx
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Class Reptilia Birds
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Class Reptilia Birds
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Subphylum Vertebrata Class Mammalia
Diversification after Cretaceous Extinction 5,000
Extant Species Hair - Keratin Mammary
Glands Homeothermic/Endothermic
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Subphylum VertebrataClass Mammalia
Diaphragm Four Chambered Heart Highly
Differentiated Teeth Large Brains Considerable
Parental Care
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Subphylum VertebrataClass Mammalia

• First Fossils 220 mya
• Coexisted with Dinosaurs
• Adaptive Radiation During Cenozoic
• Three Lines of Evolution
• Monotremes
• Marsupials
• Eutherians (Placental)

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Monotremes

• Platypus and Spiny Anteater
• Oviparous
• Reptile-like Egg
• Hair
• Milk Produced by Specialized Glands on the
  Belly
• Australia and New Guinea

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Class Mammalia

• Duckbill Platypus

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Marsupials

• Opossum, Kangaroo, Koalas
• Young Develop in a Marsupium
• Young Born at a Very Early Stage of
  Development
• Australia and South America

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Australian Mammals
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Eutherians (Placental)

• Placental Mammals
• Diverged 80 to 100 mya
• Adaptive Radiation 70 to 45 mya
• Most Diverse

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Class Mammalia Placental Mammals