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CHAPTER 14 FISH, AMPHIBIANS, AND REPTILES
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All are vertebrates and belong to the Phylum Chordata “chordates”
To be a chordate, certain characteristics must be present at sometime during its life. Notochord (p.395) - a rod-like piece of cartilage that runs along the dorsal side.
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- it is present in humans during early development.
- it turns into the backbone.
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some have a notochord their entire life. (not vertebrates).
Example 1: tunicate
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Example 2: lancelet
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nerve chord turns into the spinal cord. - carries messages from the brain.
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gill slits (pharanygeal pouches) - openings in the throat area.
- found in all vertebrates during the embryo stage. - turns into lungs.
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All vertebrates have an endoskeleton.
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Most vertebrates are ectotherms.
“cold-blooded” - their temperature changes with the environment.
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Endotherms maintain a constant temperature.
“warm-blooded”
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FISH 30,000 different species. - three classes.
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1) Class Agnatha “jawless fish” p. 402
simplest vertebrates. no jaw - has a ‘sucker’ mouth. - it sucks the fluids out of its host.
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their skeletons are made of cartilage - no real bones - very flexible.
Ex. Lampreys attack healthy fish. - live in the Great Lakes (invasive species).
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Ex. Hagfish (p. 402) - attacks dying or dead fish.
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2) Class Chondrichthyes (p. 402)
are the cartilaginous fish. Ex. sharks, rays, skates. - have skeletons made of cartilage.
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They have traits of ‘advanced’ fish.
scales - sharp and pointy. - not round. - ‘hydrodynamic’ jaws - can ‘unhinge’.
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Sharks most are not dangerous but are efficient predators.
- replaceable teeth that slant inwards. - sense of smell
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Largest = Whale shark (45 feet long) ‘Meanest’ = Great White
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- sharks can reproduce sexually in three different ways.
1) young are born ‘live’. 2) lays eggs 3) eggs ‘hatch’ inside the female.
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More sharks… Goblin Shark Thresher Shark Basking Shark Sawtooth Shark
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More Cartilage Fish Manta Ray Skate
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North Dakota Chondrichthyes
Sturgeon Paddlefish
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3) Class Osteichthyes “bony fish”
largest class of fish. (95%) Three groups: lung fish - have simple lungs and gills. ex. African lungfish
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2) lobe-finned - fins attach to the skeleton. Ex. coelacanth
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3) ray-finned paired fins with long bony spines. largest group. Ex. walleye, perch, salmon.
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ASSIGNMENT: WORKSHEET ‘FISH’
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Features of a Bony Fish lateral line - runs along the side of the fish. - can sense vibrations and electrical currents.
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gills - water passes over the gills and they extract oxygen. - release CO2 - many tiny blood vessels.
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operculum - a bony plate which covers the gills.
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swim bladder - controls buoyancy. - fills with air to rise.
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- no eyelids! two chambered heart. reproduces sexually. nostrils - a strong sense of smell.
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- have a complete digestive system.
- stomach, liver, intestines…
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WHICH CLASS OF FISH? Manta Class Chondrichthyes Lamprey Class Agnatha
Northern Class Osteichthyes
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READ “Origins of Fish” p. 406 ASSIGNMENT WORKSHEET: “GO FISH”
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Class Amphibia “Amphibians” p. 407
Ex. frogs, toads 2,500 different species.
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Amphibians must live near water.
keep skin moist. - to reproduce (lay eggs)
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Many amphibians in Minnesota have been found with deformities in recent years.
linked to the use of pesticides. - can easily be absorbed thru their skin.
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Amphibians are ectothermic.
during winter months they become inactive - slowed metabolism. - called hibernation.
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- some become inactive when temperatures are too hot or when water is scarce.
bury themselves underground. - called estivation.
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Amphibians need a strong endoskeleton to support their body while on land.
they have a three chambered heart. - more advanced than fish.
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Frogs (p. 409) have lungs but can stay under for long periods of time. - can absorb oxygen through their skin.
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- have hinged joints reproduce sexually - lay eggs in water.
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Hundreds of different species and sizes
- colors are often “bright” -poisonous
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Toads can spend more time out of the water. - skin is ‘bumpier’ - doesn’t dry out. - but must return to water to reproduce.
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Salamanders often confused with lizards. - smooth skin (no scales). - amphib with a tail.
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Caecilians - a legless, blind amphibian found in rain forests
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AMPHIBIAN METAMORPHOSIS
- the change in form from egg to adult.
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egg tadpole adult have gills - must stay in water. develops legs.
tail is absorbed. begins eating insects - protein speeds up the process. adult
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Usually takes weeks. warm water and plenty of food will increase the speed of metamorphosis. - but can take years…
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ASSIGNMENT WORKSHEET: ‘AMPHIBIANS’
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Class Reptilia ‘Reptiles’ p. 412
Ex. turtle, snakes, alligator. they do not have to return to water. 1) scales - keep moisture in.
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2) hard shell - amniotic egg - more durable.
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All* reptiles have claws.
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Reptiles have a three chambered heart
Reptiles have a three chambered heart. - provides more oxygen to the body. have lungs - are land organisms. READ ‘Importance and Origin of Reptiles’ (p. 417).
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Lizards most are small. - but the Komodo Dragon can be 10 feet long.
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most lizards are harmless.
many eat insects. - some are venomous.
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More lizards… Gila Monster Fringed Lizard Gecko Zebra Lizard
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Alligators
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Snakes reptiles without legs. can unhinge their jaw. - to swallow large prey.
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- some are venomous. Coral Snake Rattlesnake
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Some reptiles have shown maternal care.
- the mother protects the eggs and the young after they hatch.
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Reptiles are more advanced and survivable than amphibians.
- water is the greatest limiting factor.
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ASSIGNMENT: WORKSHEET ‘ECTOTHERM REVIEW’
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