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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

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Transition from Sea to Land

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•Coelacanth

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Eusthenopteron

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Panderichthys

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Tiktaalik

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Transitional TetrapodsSkull, teeth, limbs similar to lobe-

finned fish

IchthyostegaAcanthostega

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Amphibians

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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.

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Evolution of CirculationFish Amphibian

Kingdom AnimaliaPhylum ChordataSubphylum VertebrataClass 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• larvae are herbivores, adults carnivores • larva have tails to move in water• external fertilization with no parental care• lay eggs without shells in water

AMPHIBIAN METAMORPHOSIS

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• 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• Hindlegs adapted for jumping and swimming• 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”• Long tail• 2 pairs of limbsEx. Salamanders and newts

Class Amphibia:Order Gymnophiona(Apoda)

Gymnos- nakedophis- snake

live in tropicsElongated bodyLimblesscarnivores

Ex. Caecilians – “blind”-small eyes

Kingdom AnimaliaPhylum ChordataClass Reptilia

Ex: snake, turtle, lizards crocodile, dinosaurs

Reptilian Traits:3 chambered heart (except for crocodilians- imperfect 4)Ectothermic Paired limbs with five toes and clawsTough, dry, scaly skin (horny epidermal scales)

Jaws adapted for crushing and grippingBreathe with lungsmetanephric kidney- produces uric acid to reduce water loss Large cerebrum as compared to rest if 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), oviparousLay amniotic eggs on land- no dependence on

waterShells 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.

Phylum ChordataSubphylum Vertebrata

Class ReptiliaOrder 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

Turtle Shell Anatomy

Fusion of ribs, vertebrae, & carapace

Turtle Life Cycle

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

• Elongated massive skull• Imperfect 4 chambered heart• crocodiles, alligators, and caimans, gavials

Phylum ChordataSubphylum VertebrataClass Reptilia

Order Crocodilia

CrocodiliansCrocodiles, Alligators,

Caimans, & Gavials

Gavial(gharial)

Carnivores, “ghara”- pot- bulb on snout12.25- 15.5 ft. longRivers of India, Nepal, Pakistan, Bhutan, BangladeshCritically Endangered

Alligator

Crocodile

Largest, best predatosLive in/near Salt waterAmerican Crocodile- EndangeredMost in Australia

CaimanRivers/swamps of Central and South America3ft- 16 ft. (only in black caiman species)

Crocodilian Reproduction

• 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• Scales- prevents dehydration, protection• Claws• Amniotic egg• The excretory waste of the reptiles is uric acid

unlike the dilute, water wasting ammonia in the urine of Amphibians