Vertebrate Movement to Land SZ2- 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 1

Vertebrate Evolution

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

Transitional tetrapods

Transition from Sea to Land 5

6 Coelacanth

Eusthenopteron 7

Panderichthys 8

Tiktaalik 9

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Transitional Tetrapods Skull, teeth, limbs similar to lobe- finned fish Ichthyostega Acanthostega

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Struggles to Survive On Land Water conservation Gas exchange Reproduction Gravity Separation of head, flexion of a neck to pick up food

Adaptations to live on land Gills are usually lost Lungs function Breathe through skin Secrete mucus – Prevent dehydration – Aids in respiration 15

More Adaptations to live on land Skeleton – Fins evolve into limbs – Vertebral column supports body underneath it AIR IS NOT AS BOUYANT AS WATER. 16

Evolution of Circulation 17 Fish Amphibian

Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Amphibia 1 st 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

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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 Amphibia Order Anura Anura- an=without, ura= tail Tailless as adults Specialized Hindlegs adapted for jumping and swimming- frogs running- toads Tympanum (ear drum) and larynx well developed Ex. Frogs and toads frog dissection intro- oyunlari.com/files/file/kurbaga_ameliyat.swf

Class Amphibia Order Caudata Caudata- “have a tail” 2 pairs walking legs Live in freshwater or leaf litter Ex. Salamanders and newts

Class Amphibia: Order Gymnophiona(Apoda) G ymnos- naked ophis- snake live in tropics in soil Elongated body Limbless Carnivores- eat invertebrates Ex. Caecilians – “blind”-small eyes

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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 (O 2 and CO 2 ) 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 Chordata Subphylum 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 teeth Vertebrae and ribs fused Ex. Turtles and tortoises

Turtle Shell Anatomy

Fusion of ribs, vertebrae, & carapace

Turtle Life Cycle

Phylum Chordata Subphylum Vertebrata Class Reptilia Order Sphenodonta Primitive reptile closely related to dinosaur Looks like lizard Diapsid skull Ex. Tuatara- only living species

Phylum Chordata Subphylum Vertebrata Class Reptilia Order Squamata Diapsid 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 eyelids Snakes- descended from tetrapod ancestor dichotomous 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 Chordata Subphylum Vertebrata Class Reptilia Order Crocodilia

Crocodilians Crocodiles, Alligators, Caimans, & Gavials

Gavial(gharial) Carnivores, “ghara”- pot- bulb on snout ft. long Rivers of India, Nepal, Pakistan, Bhutan, Bangladesh Critically Endangered

Alligator Live in and around freshwater- wetlands and rivers East china, southern US and gulf of mexico Teeth do not interlock, can only see teeth of upper jaw when mouth is closed

Crocodile Largest, best predators Interlocking teeth Live in/near Salt water American Crocodile- Endangered Most in Australia

Caiman Rivers/swamps of Central and South America 3ft- 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, 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