Transcript Chapter 20: Vertebrates - Tenafly Public Schools

Vertebrates
Vertebrate Survey
Anatomy and Physiology of
Vertebrates
Vertebrate Evolution
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Phylum Chordata is the group of
animals with a notochord – a flexible,
supporting structure along the back
Contains the invertebrate chordates,
and Subphylum Vertebrata, which
have evolved vertebral columns
Serves as site for muscle attachment,
protects nerve cord
Trends in Vertebrate Evolution
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Development of true bony jaws
Development of paired pectoral and
pelvic limb girdles
Development of bones
Most vertebrates have two sets of
appendages (arms and legs), a closed
circulatory system with a ventral heart,
and either gills or lungs for breathing
Class Agnatha
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Jawless fish
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Ex. Lampreys and hagfishes
Only living vertebrates without jaws
Parasites – survive by attaching themselves
to other fish or aquatic animals, feeding on
their blood and body fluids
Scavengers – eat decaying carcasses
Class Chondrichthyes
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Cartilaginous fish
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Ex. Sharks, skates, rays
Skeletons made of cartilage
Some are fearsome predators, other eat
small fish, mollusks, or plankton
Class Osteichthyes
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Bony fish
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Contain half of all vertebrate species, all
aquatic habitats
Ray-finned fish – sub-class containing
almost all fish species – well-developed
bone systems, specialized jaws with teeth
Lobe-finned fish – sub-class with lungs
and gills, relatives of amphibians
Class Amphibia (amphibians)
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Lay eggs in water and spend part of
their life cycle there (gills)
As adults, live on land and breathe
through lungs
Most have moist skin, as part of their
respiration occurs through skin
Class Amphibia
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Examples include:
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Newts and salamanders (lay eggs in water,
hatch into young that resemble adults –
larvae have gills that disappear and are
replaced by lungs as they grow)
Frogs and toads (eggs hatch in water as
tadpoles, which look completely different
from adults)
Class Reptilia (reptiles)
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Fully terrestrial
Reproduce by internal fertilization –
egg/sperm fuse within body of the
female
Produce leathery eggs to prevent water
loss
Dry scaly skin to retain moisture
Developed lungs
Class Reptilia
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Order Chelonia – turtles and tortoises,
protective shell of bony plates (long
fossil record)
Order Crocodilia – crocodiles,
alligators, caimans (long fossil record)
Order Squamata – lizards and snakes,
most abundant group
Class Aves (Birds)
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Only vertebrates with feathers
Used for flight and conservation of body
heat
Lay eggs
Class Mammalia (mammals)
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Named for presence of mammary
glands, enable females to nourish
young with milk
Have hair to retain body heat
Class Mammalia
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Three groups:
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Monotremes – egg-laying mammals like duckbilled platypus – have body hair/fur, lay leathery
eggs
Marsupials – live young born very early in their
development and continue to develop within
marsupium – kangaroos, koalas, opossums
Placental mammals – largest group, names for
placenta (organ that connects mother with
developing embryo, allows for nutrient, gas, and
waste exchange)