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before birth what do all vertebrates have
- dorsal notochord: eventually forms the backbone
- post-anal tail
- dorsal nerve cords: becomes spine
- gill slits: at some point during development
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after birth what do all vertebrates have
- endoskeleton
- backbone/spine and well developed nervous system
- closed circulatory system
- ventral heart
- regulate temperature one of two ways:
- -ectotherm
- -endotherm
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define ectotherm
the internal body temperature is regulated by its surroundings
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define endotherm
- an animal which can maintain it's own body temperature at a fixed temperature
- ex) humans 37 degrees
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what are the 6 classes in phylum chordata
- class condrichthyes
- class osteichthyes
- class amphiba
- class reptilia
- class aves
- class mammalia
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what are the characteristics of class chondrichthyes
- cartilage (no bone)
- ectotherm
- 2 chambered heart
- gas exchange through gills (4-7 each side)
- lack swim bladders
- covered in epidermal placoids (tooth-like scales)
- use counter shading
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define counter shading
- used for protection and predation
- makes the animal camouflaged
- looking down at the animal, they blend with the sea
- looking up at the animal, they blend with the syunlight
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describe shark feeding
- find prey using sound waves, smell, and sight
- can detect the electrical signals of other animals because of electroreceptors in their head
- -a network of specialized cells that can detect electricity
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describe skates and rays
- pectoral fins are attached to their heads
- flattened and use camouflage
- gills located ventrally
- spiracles: breathing holes located behind the eyes
- teeth are flattened to crush molluscs
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what are the characteristics of class osteichthyes
- bony fish
- swim bladder present: fills with gas to help with buoyancy
- ectotherms
- aquatic
- gas exchange through gills
- two chambered heart
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describe class agnatha
- jawless fish
- ex) lampreys and hagfish
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what are the characteristics of class amphibia
- ex)tadpoles, frogs, toads, newts, and caecilians
- aquatic and terrestrial
- ectotherms
- 3 chambered heart
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describe gas exchange in amphibians
- lungs in adults
- juveniles may have gills
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describe amphibian movement
- use four limbs (tetra pods)
- caecilians: worm-like and don't have limbs (use bristles and segmentation)
- tree frogs have special toe pads that stick on trees
- swim using webbed feet
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describe the respiration system of amphibians
- breathe through gills, skin, and lungs
- take in oxygen through skin; ozygen enters the bloodstream directly
- amphibians use lungs on land and diffusion in water
- larvae use gills
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what are the two frog membranes
- tympanic membrane
- nictitating membrane
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describe the tympanic membrane
- located just behind the eye
- like an external eardrum
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describe the nictitating membrane
- a third, semitransparent eyelid that covers the whole eye
- helps the frog see under water and hife from predators
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what are the characteristics of class reptilia
- ex) crocodiles, sea turtles, rattle snakes
- amniotic egg
- soft leathery shell
- birds and mammals evolved from reptiles
- ectotherms
- 3-4 chambered heart
- mostly terrestrial
- gas exchange through lungs
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define amniotic egg
eggs capable of being laid in dry conditions
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what are the adaptations of reptiles
- protective shell (turtles)
- dry, watertight skin, covered with overlapping scales (snakes)
- limbs absent in some (snakes)
- nest built for young
- fertilize internally and lay eggs
- some give birth to live bodies (garter snakes)
- parthenogenesis
- some lose their tail, have venom, or sharp teeth
- shed skin
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define parthenogenesis
a rare process in which eggs become embryos without male fertilization
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describe the vomeronasal organ
- chemosensory organ in the roof of the mouth
- scent particles are sensed when the snake flicks its tongue in and out
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describe thermo sensory
- heat-sensing organ
- in the pit below the eye and along the upper or lower jaw
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what are the characteristics of class aves
- ex) robins, eagles, hawks, geese, swans
- hollow bones for flight
- lack teeth (beak)
- endothermic
- 4 chambered heart
- front limbs are wings
- legs covered in scales
- have feathers (modified scales)
- birds malt their feathers
- lungs and air sacs
- internal fertilization (lay eggs)
- chicks use egg tooth to hatch
- furcula or 'wishbone' is in the bird's chest which prevents chest cavity decompression during flight
- most are carnivorous, some are scavengers
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what are the 5 types of feathers
- contour
- semiplume
- filoplume
- down
- bristle
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define contour
gives the shape and colour of bird
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define semiplume
1/2 contour + 1/2 down; provides insulation
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define filoplume
believed to have a sensory function
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define down
provides insulation
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define bristle
- found around the eyes and mouth
- protective function
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why do scientists suggest that birds evolved from dinosaurs
- reptiles and birds share common characteristics
- the Archaeoteryx is the link between dinosaurs and modern day birds
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what is the characteristics of class mammalia
- ex) humans, platypus, cats, whales, rhinos etc
- hair
- mammary glands: provide milk for young
- teeth
- diaphragm: separates lungs/abdomen
- lugns
- endotherms
- 4 chambered hear
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what are the 3 sub classes of mammals
- monotremes: egg laying mammals
- marsupials: pouched mammals
- placentals: placenta for nutrients
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describe monotremes
- egg laying mammalls
- ex) platypus, anteater
- carry eggs in pouches
- body temp of ~32 degrees
- nurse young after hatching
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describe marsupials
- pouched animals
- body temp ~35 degrees
- give birth to live young but very undeveloped
- in a protective pouch, young attach to nipples and continue to develop
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describe placentals
- placenta for nutrients
- most mammals (humans, whales)
- body temp 37 degrees
- placenta: nutritive connection between embryo and uterus
- young are well-developed when born
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