Understanding Reptiles and Birds: Characteristics, Adaptations, and Evolution

1. Reptiles and Birds Ms. Moore

2. What is a Reptile? • Body Plan: land vertebrates • Well-developed skull • Backbone and tail • Two limb girdles with four limbs • A reptile is a vertebrate that has a dry, scaly skin, lungs, and terrestrial eggs with several membranes. • Evolved from amphibian-like ancestors; developed under dry conditions; age of the dinosaurs (variety)  extinction

3. Form and Function in Reptiles • Body Temperature Control • Ectotherms: rely on behavior to control body temp. • Feeding • Mostly herbivores or carnivores with adaptations to assist in feeding • Respiration • Cannot diffuse through skin, use spongy lungs surrounded by muscles to help expand and collapse cavity • May have flaps of skin over nostrils to help when underwater • Most have two lungs, some snakes only have one

4. Circulation • Double-loop (1 to lungs, the other to body) • 3 or 4 chamber heart with partial septum dividing the ventricle (crocodiles) • Excretion • Urine (ammonia or uric acid) produced in kidneys  bladder/cloaca • Response • Similar to amphibian; cerebrum and cerebellum are larger • Reptiles have a pair of nostrils and sensory organs in roof of mouth = smell • Simple ears with external eardrum and 1 bone • Body heat detectors

5. Movement • Wide variety of movements specialized to body • Reproduction • Internal Fertilization! Penis-like organ delivers sperm to female cloaca • Embryos are covered with membranes and a leathery shell • Most are oviparous, some are ovoviviparous • Amniotic egg: embryo can develop without drying out • 4 membranes: • Amnion: surrounds and cushions developing embryo • Yolk sac: food supply • Chorion: regulates gas exchange • Allantois: stores waste from embryo

6. Groups of Reptiles • Lizards and Snakes • Order: Squamata, means “scaly reptiles” • Lizards: have legs, clawed toes, external ears, and movable eyelids • Snakes: lost both pairs of legs during evolution; efficient predators; some can produce venom *Draw Figure 31-8: The Amniotic Egg (p803) • Crocodilians • Order: Crocodilia • Crocodiles: habitat includes fresh or salt water; native to Africa, India, SE Asia • Alligators: habitat includes fresh water; native to N/S Americas • Caimans: same as alligator, but smaller • Gavials • Fierce carnivores; guard eggs/young

7. Turtles and Tortoises • Order: Testudines • Turtle: lives in water • Tortoise: lives on land • Terrapin: found in water that is somewhat salty • Shell is built into the skeleton: • Carapace: dorsal part • Plastron: ventral part • No teeth, horny ridges that cover the upper and lower jaws • Powerful limbs • Tuataras • Order: last surviving member of Sphenodonta • Found off the coast of New Zealand • Resemble lizards, but lack external ears and retain primitive scales; have a “third eye” (part of brain)

8. What is a Bird? • Birds are reptile-like animals that maintain a constant internal body temperature. They have an outer covering of feathers, two legs covered with scales, and two front limbs modified into wings. • Feathers: made mostly of protein and develop from pits in the bird’s skin • Evolution • Believed to evolve from extinct reptiles/dinosaurs • Archaeopteryx: early bird or transitional animal of both dinosaurs and birds? • Did birds and dinosaurs both evolve from an earlier common ancestor?

9. Form, Function, and Flight • Body Temperature Control • Endotherm: generate own body heat; high metabolism rate • Feeding • Beaks are adapted to the bird’s diet • Remember: Crop and Gizzard? • Respiration • Highly efficient; allows birds to maintain their high metabolic rate = flight • Air sacs: direct air through the lungs in a one way flow

10. Circulation • 4 chambered hearts; 2 separate circulatory loops • Excretion • Similar to reptiles, except uric acid crystals can be seen in a white, pasty form • Response • Well-developed sense organs; brain that can quickly interpret and respond to signals • Cerebrum: behaviors like nest building, flying, care of young, courtship, and mating (very large) • Cerebellum: uses precise, coordinated movements • Medulla Oblongata: heartbeat • Optic Lobe: eyesight; see color very well • Olfactory Bulb: smell; very small

11. Movement • Some birds cannot fly: • Ostrich: walk/run • Penguin: swim • Bones form a sturdy, but lightweight frame • Large chest muscles power flight • Reproduction • Both male and female reproductive tracts open to the cloaca “cloacal kiss”; some may have penis • Amniotic eggs with hard outer shells; incubated until hatch

12. Groups and Ecology • Over 30 orders of birds • Passerines/Perching Birds: songbirds; over 5000 species • Pelicans and Relatives: aquatic ecosystems • Parrots: colorful and noisy; feet holds food • Herons and Relatives : wading in aquatic habitats • Cavity-Nesting: live in holes made in trees, mounds, or underground tunnels • Birds of Prey: raptors; fierce predators with hooked bills and sharp talons • Ostrich and Relatives: flightless birds