Phylum Chordata Flashcards
Anotomical features of chordates?
Notched
Dorsal, hollow nerve cord
Pharyngitis slits
Muscular post-anal tail
Vertebrates are chordates that have…
A backbone
Notochord
A long flexible rod between the digestive tube and nerve cord
Most adults don’t keep it
Hollow nerve cord
Develops from extoderm
Sits dorsal to the notochord
Developes into brain and spinal chord
Pharyngeal slits
Slits in pharynx that open to the outside of the body.
Develops into gills for fish or parts of ear, head and neck in tetrapods
Muscular post-anal tail
Posterior to the anus.
Contains skeletal elements and muscles
Provides movement and balance
Developmental chain of chordates
Vertebrae, Jaws, lungs, lobed fins, limbs with digits, amniotic egg, milk
Vertebrates derived characteristics
Vertebrae enclose spinal cord
Elaborate skull
Fin rays in aquatic forms
Lamprey
Jawless fish
Notochors becomes main axial skeleton
Lack true backbone
Cartilage skeleton
Parasitic
Chondrichthyes
Fish with cartilage skeleton and jaws
Sharks! Rays too
Carnivores with good senses
Cloaca
Large oily liver and streamlined for buoyancy
Chondrichthys vs Osteochthyes
First has cartilage skeleton, second has bony skeleton
Bony fish
Swim bladder
External fertilization mostly
Gills for breathing
Bony fish: Ray fins
Most fish
Long rays in fins
Bony fish: Lobe-fins
Muscular pectoral and pelvic fins
What are tetrapods believed to be evolved from?
Tiktaalik
A lobe-fin fish that could prop itself on its fins to breate air above the surface
Tetrapod characteristics
Four limbs, feet with digits
Bones of pelvic girdle are fused to backbone
Lungs instead of Gills
Ears for airborne sounds
Amphibians include…
Feogs, salamanders, caecilians
Why are amphibians stuck in moist environments?
Need moise skin to breathe
External eggs dry out
Metamorphosis (tadpoles are entirely aquatic)
Amniotic egg special membranes for…
Gas exchange
Store nutrients
Store waste
Reptilian Characteristics
Body scales give waterproof barrier
Lungs
3 or 4 chambered heart
Lay eggs on land
Ectothermic
Birds seperate from reptiles
Endothermic
Feathers and wings
4 chambered hearts
Sternum with strong chest muscles
Advantages of flight
Better hunting and scavenging
Can eat flying bugs
Escape from Predators
Migration
Mammalian characteristics
Mammary glands
Hair
Specialized teeth
Larger brain than other vertebrates
Endothermy (4chamber heart, diaphragm, fat layer under skin)
Mammles: Monotremes
Platypus and Echidnas
Lays eggs
Milk but no nipples
Cloaca
Mammles: Marsupials
Mammals with pouches (kangaroos, opossums, koalas)
Born early in development to move to pouch
A marsupials pouch is called…
A marsupium
Mammals: Eutherians
Placentas
Longer pregnancy
