Transcript Ch. 31.1x
Reptiles Ch. 31.1 What is a Reptile? • • • • • Land vertebrate Well developed skull Backbone and tail 2 limb girdles 4 limbs • 2 exceptions: – Snakes (limbless) – Turtles (hard shells that are fused to vertebrate) • Reptiles: dry, scaly skin, lungs, and lay terrestrial eggs with several membranes • Live their entire lives out of water • Skin is dry and has thick, protective scales – Scales can be smooth or rough • Dry, waterproof skin helps with living in dry environments. – Not always good though. The skin is frequently shed • Reptiles are found widely through the Earth. • Very diverse lifestyle and look • Can’t live in very cold climates Evolution of Reptiles • Fossils of 1st reptiles from ~350 mya • Earth’s climate became cooler and less humid – Lakes and swamps dried up and reptiles evolved to live in that dry area Mammal-like Reptiles • Displayed a mix of reptilian and mammalian characteristics • Dominated many land habitats • Went extinct quickly (replaced by DINOSAURS in the fossil record) Enter the Dinosaurs • Late Triassic and Jurassic time periods – Very diverse and large number of reptiles – 2 aquatic groups were in the seas – Ancestors of turtles, crocodiles, lizards, and snakes – Dinosaurs were everywhere • • • • • • Dinosaurs varied in size Quadriped or biped Herbivore or carnivore Lived as ‘families’ Laid eggs Two main groups – ORNITHISCHIA – bird hipped – SAURISCHIA – lizard hipped Exit the Dinosaurs • Mass extinction – Natural disasters: volcanic eruptions, lava flows, dropping of sea level, asteroid in the Yucatan Peninsula • Major forest fires and dust clouds Form and Function in Reptiles • • • • • • • Well developed lungs Double loop circulatory system Water conserving excretory system Strong limbs Internal fertilization Shelled, terrestrial eggs Controllable body temperature • Body Temperature Control: ectothermic – rely on behavior to regulate temp. • Feeding: wide range of food • Respiration: spongy lungs provide more gas exchange • Circulation: efficient double loop – Blood to and from the lungs; blood to and from the rest of the body • Heart has 2 atria and 1-2 ventricles • Excretion: urine is produced in the kidneys, urinary bladder stores urine and released in the cloaca • Response: complex eyes and can see color, good sense of smell, mouth can ‘taste’ chemicals, can pick up vibrations/hear • Movement: legged reptiles have stronger limbs; rotated further under the body; flippers for aquatic turtles • Reproduction: internal fertilization; oviparous (lay eggs that develop outside mother’s body) – Eggs have amnion, yolk sac, chorion, and allantois Groups of Reptiles • Lizards and Snakes: SQUAMATA (scaly reptiles) • Crocodilians: CROCODILIA (long and broad snout, squat appearance) • Turtles and Toroises: TESTUDINES (shell built into the skeleton; carapce [dorsal], platron [ventral] • TUATARAS: SPHENODONTA (resemble lizards Ecology of Reptiles • Habitats are endangered • Hunting