Reptiles and Birds

Reptiles and BirdsMs. Moore

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

What is a Reptile?

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

Form and Function in Reptiles

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

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

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

Groups of Reptiles

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)

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?

What is a Bird?

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

Form, Function, and Flight

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

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

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

Groups and Ecology