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Chordate Notes
The phylum Chordata contains mostly animals with a back bone, but a few that do not.
There are 4 characteristics to classify something as a chordate.
 Dorsal hollow nerve cord
 Notochord-flexible, yet supportive rod that runs through the body below the
nerve cord
 Pharyngeal Slits- paired slits in the throat region
 Postanal tail- extends beyond the anus
Chordates must have all 4 of these things SOMETIME DURING LIFE. Your notochord
is homologous to your vertebral column, and your pharyngeal slits closed up in utero.
Groups of invertebrate chordates:
 Urochordata- tunicates
drawing:
Some are sessile, some float in water
 Cephalochordata- lancelets
drawing:
Dig into sand with anterior region sticking out
Groups of Vertebrate Chordates:
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Fish: heterothermic, aquatic vertebrates with paired fins, scales, and gills (from
pharyngeal slits). Have a single loop for circulation: vessels run across the gills,
pick up oxygen and move to the rest of the body. There are 3 groups:
o Agnathan- jawless fishes: hagfish, lamprey
o Chondrichthyes- cartilaginous fishes: sharks, rays
o Osteichthyes- bony fishes: carp, salmon, catfish, snapper, etc.
Amphibians: heterothermic, Earliest amphibians evolved several adaptations
that helped them live at least part of their lives out of the water. Appendicular
musculature and skeleton of amphibians became stronger; permitting more
efficient movement. Lungs and breathing tubes enabled amphibians to breathe
air. Early development must be in water, after metamorphosis, they can live
upon land. Gas exchange occurs in lungs, gills, and across skin (makes them
susceptible to pollution), double loop circulatory system, 3 chambered heart.
Examples include:
 Anura- frogs, toads: jumping limbs, aquatic or land
 Caudata- salamander, newts: paired limbs, long tail, can have external
gills
 Apoda- caecelians: legless amphibians, burrowing
Reptiles: heterothermic, can lay eggs on land (amniotic eggs) with leathery outer
covering and the aquatic environment is inside the egg, well-developed lungs,
double loop circulation, 3 chambered heart, scaly skin
 Testudinata- turtles: skeleton is fused to the shell
 Sphenodontia- tuatara: lizard-like reptile
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Serpentes- snakes, legless, musculature has made them one of the most
successful groups- located everywhere in the world except Antarctica and
New Zealand
 Crocodylians- alligators and crocodile
 Amphisbaena- legless, wormlike reptiles
Birds: homeothermic, evolved from a branch or reptiles. 4 chambered heart,
double loop circulation, lungs and air sacs create a double breathing pattern,
hollow bones for flight, outer covering of feathers for flight, hind limbs are scaly
and are modified for perching, grasping, or walking, front limbs are modified for
flight. Examples include: pelicans, canaries, grackles, ratites (flightless birds),
penguins, etc.
Mammals: homeothermic, covered in hair at sometime during life, have
mammary glands, 4 chambered hearts, double loop circulation, etc.
 Monotremata- egg laying mammals, ex: platypus, echidna
 Metatheres- marsupials, bear live young at an early stage, finish
development attached to a nipple. Only about half actually have the
trademark pouch, and some pouches face anteriorly while other open
posteriorly. Examples: kangaroos, oppossums, possums, koala, wallaby
 Eutheres- placental mammals: bear live young fully developed
 Rodentia- ever-growing incisors (front two teeth) rodents include
beavers, porcupines, squirrels, mice, groundhogs, capybara, etc. Most
diverse group
 Chiroptera- bats; there are macrochiroptera like flying foxes, and
microchiroptera like the ones found in the Americas
 Perissodactyla- odd toed hoofed animals-tapirs, rhinos, zebras, horses
 Artiodactyla- even-toed hoofed animals- goat, sheep, camel, deer,
giraffe, pigs
 Proboscidian- elongated nose is trunk- elephants
 Carnivora- defined by their teeth, examples include: dogs, cats,
raccoons, bears, skunks, seals, walruses
 Lagomorpha- two pairs of incisors- rabbits, hares, pikas
 Cetacea- whales and dolphins
 Sirenia- manatees and dugongs
 Primates- highly developed brains, opposable thumbs- lemurs, apes,
gorillas, humans, aye ayes
 Others including scaly anteaters, shrews, insectivores, anteaters,
armadillos, sloths
Chordate Notes
The phylum Chordata contains mostly animals with a _______________, but a few that
do not. There are 4 characteristics to classify something as a chordate.




Chordates must have all 4 of these things ____________________________. Your
notochord is homologous to your _______________, and your pharyngeal slits closed up
_______________.
Groups of invertebrate chordates:
 Urochordata- ___________
drawing:
Some are sessile, some float in water
 Cephalochordata- __________
drawing:
Dig into sand with anterior region sticking out
Groups of Vertebrate Chordates:



Fish: ________________, aquatic vertebrates with paired _________, scales, and
gills (from pharyngeal slits). Have a ______________ for circulation: vessels run
across the gills, pick up oxygen and move to the rest of the body. There are 3
groups
o Agnathan- jawless fishes: ________________________________
o Chondrichthyes- cartilaginous fishes: ______________________
o Osteichthyes- ________________: carp, salmon, catfish, snapper, etc.
Amphibians: ___________________, Earliest amphibians evolved several
adaptations that helped them live at least part of their lives out of the water.
____________________ musculature and skeleton of amphibians became
stronger; permitting more efficient movement. Lungs and breathing tubes
enabled amphibians to breathe air. Early development must be in water, after
metamorphosis, they can live upon land. Gas exchange occurs in __________,
_____________, and across __________ (makes them susceptible to pollution),
double loop circulatory system, 3 chambered heart. Examples include:
 Anura Caudata Apoda- caecelians:
Reptiles: ____________________, can lay eggs on land (__________ eggs) with
leathery outer covering and the aquatic environment is inside the egg, welldeveloped lungs, double loop circulation, ____chambered heart, scaly skin





TestinataSphenodontiaSerpentes- snakes, legless, musculature has made them one of the most
successful groups- located everywhere in the world except
_________________________________
 Crocodylians- _________________________________
 Amphibaena- ____________________________________
Birds: ________________, evolved from a branch or reptiles. __chambered heart,
double loop circulation, lungs and air sacs create a double breathing pattern,
hollow bones for flight, outer covering of feathers for flight, hind limbs are scaly
and are modified for perching, grasping, or walking, front limbs are modified for
flight. Examples include: pelicans, canaries, grackles, __________ (flightless
birds), penguins, etc.
Mammals: ____________________, covered in _______ at sometime during life,
have _________________, ________ chambered hearts, double loop circulation,
etc.
 Monotremata- ___________________________, ex: platypus, echidna
 Metatheres- marsupials, bear live young at an early stage, finish
development attached to a ___________. Only about half actually have the
trademark pouch, and some pouches face _____________ while other open
______________. Examples: kangaroos, oppossums, possums, koala,
wallaby
 Eutheres- ____________ mammals: bear live young fully developed
 Rodentia- ever-growing _________ (front two teeth) rodents include
beavers, porcupines, squirrels, mice, groundhogs, capybara, etc. Most
diverse group
 Chiroptera- bats; there are ________________________ like flying foxes,
and ____________________ like the ones found in the Americas
 Perissodactyla- ________________________-tapirs, rhinos, zebras,
horses
 Artiodactyla- __________________________- goat, sheep, camel, deer,
giraffe, pigs
 Proboscidian- elongated nose is trunk- _________________
 Carnivora- defined by their teeth, examples include:
_______________________________________________________
 Lagomorpha- two pairs of incisors- _______________________
 _________________- whales and dolphins
 _________________- manatees and dugongs
 ________________- highly developed brains, opposable thumbslemurs, apes, gorillas, humans, aye ayes
 Others including scaly anteaters, shrews, insectivores, anteaters,
armadillos, sloths