vertebrate movement to land sz2- students will explain evolutionary history of animals over the...
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Vertebrate Movement to LandSZ2- Students will explain
evolutionary history of animals over the history of life on earth.
• Tetrapods- Animals with 4 limbs– Amphibians– Reptiles– Birds– Mammals
• Evolved from fish
Why did vertebrates begin to move onto land 380 million years ago?
• Competition for food and habitat in aquatic ecosystems
• Escape predators• Availability of new food source and terrestrial
niches
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Tiktaalik
http://www.youtube.com/watch?v=HyJAV-Jf9dohttp://tiktaalik.uchicago.edu/index.html
Struggles to Survive On Land• Water conservation• Gas exchange• Reproduction • Gravity• Separation of head,
flexion of a neck to pick up food
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Adaptations to live on land
• Gills are usually lost• Lungs function• Breathe through skin• Secrete mucus – Prevent dehydration– Aids in respiration
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More Adaptations to live on land
• Skeleton – Fins evolve into limbs– Vertebral column
supports body underneath it
AIR IS NOT AS BOUYANT AS WATER.
Kingdom Animalia
Phylum Chordata
Subphylum Vertebrata
Class Amphibia1st land vertebrates
Ex: frogs, toads, & salamanders
Class Amphibia – “Double Life”frogs, toads, salamanders, & newts
Characteristics• “Double Life” -lives part of
its life in water and part on land
• Ectothermic- “outside heat”- body temp. regulated by environment
• no scales or claws• Have thin, moist skin
Egg- tadpole- adult• external fertilization with no parental care• lay eggs without shells in water• larvae are herbivores, adults carnivores • larva have tails to move in water
AMPHIBIAN METAMORPHOSIS
• Amphibian Body Plan– Bilateral symmetry– 3 chambered heart– Larvae breathe through gills; adults breathe
through lungs– Breathe through thin, moist skin (produces
mucus)– Changes from larva to adult through
the process of metamorphosis
Class AmphibiaOrder Anura
• Anura- an=without, ura= tail• Tailless as adults• Specialized Hindlegs adapted for jumping and
swimming- frogsrunning- toads
• Tympanum (ear drum) and larynx well developedEx. Frogs and toadsfrog dissection intro-http://www.kiz-oyunlari.com/files/file/kurbaga_ameliyat.swf
Class AmphibiaOrder Caudata
• Caudata- “have a tail”• 2 pairs walking legs• Live in freshwater or
leaf litterEx. Salamanders and newts
Class Amphibia:Order Gymnophiona(Apoda)
Gymnos- nakedophis- snake
live in tropics in soil
Elongated bodyLimblessCarnivores- eat invertebratesEx. Caecilians – “blind”-small eyes
Kingdom Animalia
Phylum Chordata
Class Reptilia
Ex: snake, turtle, lizards
crocodile, dinosaurs
Reptilian Traits:
3 chambered heart (except for crocodilians- imperfect 4)
Ectothermic
Paired limbs with five toes and claws
Tough, dry, scaly skin (horny epidermal scales)
Jaws adapted for crushing and gripping
Breathe with lungs
metanephric kidney- produces uric acid to reduce water loss
Large cerebrum as compared to rest of brain-
behaviors- 1. instinct 2. learned
Reptile Legs
• Short tetrapods for walking
• Positioning of the legs more directly under the animal. This position provided more support than the splayed arrangement of the Amphibian legs.
Reproduction:Internal fertilization (to avoid desiccation of
gametes), oviparous
Lay amniotic eggs on land- no dependence on water
Shells leathery, sometimes calcareous
Amniotic Egg Structures & Functions• Chorion provides a special hard covering that is permeable
to respiratory gases (O2 and CO2) while being impermeable to water vapor.
• Allantois is a storage reservoir for metabolic waste products such as nitrogenous compounds and gas exchange.
• Amnion is a fluid filled sac that acts as a cushion for the embryo and also prevents desiccation.
• Yolk sac contains food for the embryo, thus eliminating the need for a larval stage.
Checkpoint
1. List basic traits of reptiles.
2. How do reptiles reproduce? Explain fertilization
type, type of eggs, egg development.
3. Which class of animals is better adapted for life on
land, Amphibia or Reptilia?
4. Explain how your chosen class of vertebrates is
better adapted for life in terrestrial ecosystems.
Phylum ChordataSubphylum Vertebrata
Class Reptilia
Order Testudine:
Body in a bony case -dorsal carapace(top of shell) - ventral plastron(bottom of shell)Jaws with a horny beak, no teethVertebrae and ribs fusedEx. Turtles and tortoises
Phylum ChordataSubphylum VertebrataClass ReptiliaOrder Sphenodonta
• Primitive reptile• closely related to dinosaur• Looks like lizard• Diapsid skullEx. Tuatara- only living species
Phylum ChordataSubphylum VertebrataClass Reptilia
Order SquamataDiapsid skull with two temporal openings
Skin is shed with horny epidermal scales
Jacobson’s organ- sense of smell
Movable skin, kinetic skull
Poisonous- hemotoxins (blood) , neurotoxins(nervous system)
EX. Snakes and lizards
Lizards have movable eyelidsSnakes- descended from tetrapod ancestordichotomous key
Evidence suggests that Snakes descended from tetrapod ancestor• Pythons, and other
species of snakes are sometimes born with vestigial hindlimbs
• Snakes have DNA to code for a pelvis, and limbs, but genes are turned off early in development
• Elongated massive skull• Imperfect 4 chambered heart• crocodiles, alligators, and caimans, gavials
Phylum ChordataSubphylum VertebrataClass Reptilia
Order Crocodilia
Gavial(gharial)
Carnivores, “ghara”- pot- bulb on snout12.25- 15.5 ft. longRivers of India, Nepal, Pakistan, Bhutan, BangladeshCritically Endangered
Crocodile
Largest, best predatorsLive in/near Salt waterAmerican Crocodile- EndangeredMost in Australia
• The temperature inside the nest of several crocodilian species decides the sex of the young. ~50-80 eggs
• If the nest temperature is 30ºC, females will hatch
• If the temperature is above 34ºC - males.
• If the temperature is in between- young of both sexes.
Land Adaptations for Reptiles• Legs underneath bodies (tetrapods)• Lungs • more efficient circulatory system, hearts• Scales- prevents dehydration, protection• Claws• Amniotic egg, internal fertilization• The excretory waste of the reptiles is uric acid
unlike the dilute, water wasting ammonia in the urine of Amphibians
• Higher cerebral capacity for learned behavior