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Phylum Vertebrates
Chapter Chordata Bilaterally symmetrical Deuterostomes Contain 2 subphyla of invertebrates Tunicates and lancelets Hagfishes Vertebrates
Related Based on shared body plan features (coelom, symmetry, etc.)
Milk Amniotic egg Legs
Lobed fins Lungs Jaws Vertebral column Head Brain Notochord
4 Key Characteristics of Chordates Notochord longitudinal, flexible rod Hollow nerve cord Pharyngeal slits Postanal tail, often lost postembryo
Notochord SUPPORT (not a nerve cord)
Notochord remnant in inter-vertebral discs
Tunicates Larvae have chordate morphology Use tail muscles and notochord to swim to substrate, settle in Radical metamorphosis to adult
Lancelets Larvae have chordate traits Maintain chordate traits as adult (still larvalike)
Expression of developmental genes Lancelets use Hox genes to form cranial bulb Vertebrates use same Hox genes to form more elaborate brain
What next? How about a head? Craniate development
What's a Vertebrate?
Possess neural crest (embryonic cells)
They form: -Bones and cartilage of cranium - neurons and sense organs
What's a Vertebrate?
CEPHALIZATION ("getting a head") - Cranium, brain, eyes, ears, nose concentrated at head end of animal helps with active lifestyle
What's a Vertebrate?
Bilateral symmetry = dorsal, ventral, left, right, cranial, caudal (tail) directions make sense
What's a Vertebrate?
Vertebral column
Derivatives of pharyngeal slits and bars in vertebrates
Jaws, jaw support Gills and gill supports Aortic arches and other important blood vessels Some muscles
Human embryo 4.5 weeks
Dog
Bat
Hare
Man
Vertebrates
Respiratory and circulatory adaptations to support active tissues, efficient hearts Closed circulatory system (blood stays in vessels) Diverse adaptations for feeding and digestion
Vertebrates have Strong axial skeleton
Strong, diverse appendicular skeletons (with limbs); extensive use of bone
Vertebrates
Hagfish
Jawless Fish
Lamprey Notochord and vertebralike projections Rasplike teeth, no mineralized bone
- have cartilage skull and notochord, no vertebrae - Parasitic or scavengers - tooth-like structures (keratin)
Jawed Fish -Strong, complex internal skeletons (cartilage or bone) -Well developed appendages (fins) -Jaws open diverse new feeding opportunities, eat larger food particles -Bony fish most diverse group of vertebrates -Both groups evolved from ancestors with bony skeletons (regression bone of in sharks)
Cartilage fish Bony fish
Jawed Fish Sharks and Rays
Cartilage skeleton, some ovoviviparous/ have a cloaca (one exit only)
Ray-finned fish
Bony skeleton/bony scales Gills covered by operculum
Lobe-finned fish
Rod-shaped bones in pectoral and pelvic fins 3 lineages alive today
Coelacanths Lungfishes Tetrapods
Amphibians
Amphibians frogs, toads, salamanders, caecilians (legless, worm-like)
First tetrapods (= "four-footed) = terrestrial Reproduction in most amphibians tied to water (eg. Tadpoles and frogs) External reproduction, some spp. have metamorphosis (frogs) Require water or damp habitat, many use moist skin for gas exchange
Amniotes All have amniotic egg with extraembryotic membranes (not part of embryo's body) In reptiles, birds and some mammals egg has a shell
Allows wider habitat than amphibians
In other amniotes, development in the mother
Amniotes
Reptiles
Reptiles first successful terrestrial vertebrates Skin very resistant to water movement (scales with keratin) Rib cage movement ventilates lungs
Reptiles
Clade includes lizard, snakes, turtles, crocodilians and BIRDS! Most are oviparous, shelled eggs laid on land
Many spp of snakes and lizards are viviparous (live birth)
Most are ectothermic (absorb external heat)
But, birds are endothermic (internal heat)
Birds Have many body adaptations for flight, eg. Wings, feathers, hollow bones, cloaca, gonads Flight benefits in h...