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

Transition from Sea to Land

Coelacanth

Eusthenopteron

Panderichthys

Tiktaalik

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

Fig. 25.CO Amphibians

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

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

Evolution of Circulation Fish Amphibian

Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Amphibia 1st 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

AMPHIBIAN METAMORPHOSIS 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

Fig. 25.8

Fig. 25.26

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 Hindlegs adapted for jumping and swimming Tympanum (ear drum) and larynx well developed Ex. Frogs and toads frog dissection intro- http://www.kiz-oyunlari.com/files/file/kurbaga_ameliyat.swf

Class Amphibia Order Caudata Caudata- “have a tail” Long tail 2 pairs of limbs Ex. Salamanders and newts

Class Amphibia: Order Gymnophiona(Apoda) Gymnos- naked ophis- snake live in tropics Elongated body Limbless carnivores Ex. Caecilians – “blind”-small eyes

Kingdom Animalia Phylum Chordata Class Reptilia Ex: snake, turtle, lizards crocodile, dinosaurs

3 chambered heart (except for crocodilians- imperfect 4) Ectothermic 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 Solid nitrogen wastes - due to metanephric kidney 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), 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. 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.

Order Testudine: Body in a bony case dorsal carapace(top of shell) 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

Order Squamata Diapsid skull with two temporal openings 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

Elongated massive skull Imperfect 4 chambered heart Phylum Chordata Subphylum Vertebrata Class Reptilia Order Crocodilia Elongated massive skull Imperfect 4 chambered heart crocodiles, alligators, and caimans, gavials

Crocodilians Crocodiles, Alligators, Caimans, & Gavials

Gavial

Alligator

Crocodile

Caiman

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