Chapter 31
Reptiles and Birds

31.1: Reptiles pgs. 796-805

Characteristics of Reptiles






Class Reptilia

Means – to creep
First animals to adapt to land
Have dry scaly skin w/ claws
Have lungs
Legs at right angles from body

Provides greater support and make walking and running on land easier
Most have 3 chambered heart; some have 4 chambered heart (crocodilians)

Characteristics of Reptiles




Ectotherms (cold blooded)
Most are herbivores but some are carnivores
Internal fertilization (sexually)

Lay eggs on land ( amniotic eggs )

Provides nourishment and protection to developing embryo
Use sense organs to detect prey or ID chemicals

What is a Reptile?

Ectotherms (cold
Blooded) with dry, scaly skin, with claws on their toes

More advanced 3 chambered hearts
(crocs have 4)

What is a Reptile?


Amniotic eggs
Allows reptiles to be successful on land

Evolution Reptiles
 Reptiles were the first animals to adapt their eggs to dry habitats
 First reptiles are from 350 mya
 Did not become common until about 40-50 million years later when the conditions of Earth were drier

Mammal-Like Reptiles
 At the end of the Permian Period ~245 mya, a great variety of reptiles roamed the Earth

Mammal-Like Reptiles
 Displayed a mixture of mammalian and reptilian characteristics
 Dominated many land habitats
 Became extinct in just a few million years

Replaced by another group of reptiles…

Enter the Dinosaurs

Late Triassic and Jurassic periods
 Two groups of large aquatic reptiles swam in the seas
 Ancestors of modern turtles, crocodiles, lizards, and snakes populated many land habitats

Enter the Dinosaurs
 Dinosaurs were everywhere!

Saurischia: lizard-hipped dinosaurs
 Ornithischia: bird-hipped dinosaurs
 Dinosaurs are the ancestors of modern birds

Exit the Dinosaurs
 Mass Extinction 65 mya: the end of the Cretaceous Period
 Caused by a dramatic series of natural disasters
 Volcanic eruptions, dropping in sea level, huge asteroid or comet smashing into the now Yucatan
Peninsula in Mexico, etc.

Opened up niches on land and in the sea, providing opportunities for other kinds of organisms to evolve

Body Temperature Control

Reptiles are ectotherms



They rely on behavior to help control body temperature
To warm up, they bask in the sun
To cool down, they move to the shade

Reptile Feeding & Respiration


Reptiles range from herbivores to carnivores
The lungs of reptiles are spongy, providing more gas exchange area than those of amphibians

Most reptiles have 2 efficient lungs to exchange gas with the environment

Reptile Circulation

Reptiles have an efficient double-loop circulatory system

Their heart contains two atria and either one or two ventricles

Reptile Circulation

Reptile Excretion

Urine is produced in the kidneys of reptiles

By eliminating wastes that contain little water, a reptile can conserve water

Reptile Response

The basic pattern of a reptile’s brain is similar to that of an amphibian


In addition to a pair of nostrils, most reptiles have a pair of sensory organs in the roof of the mouth that can detect chemicals
Reptiles have simple ears and can pick up on ground vibrations and body heat

Reptile Reproduction



All reptiles reproduce by internal fertilization
Most reptiles are oviparous (lay eggs that develop outside the mother’s body)
Reptilian eggs are amniotic

They contain a shell and membranes that create a protected environment in which the embryo can develop without drying out

Structure of an Amniotic Egg

Groups of Reptiles

4 orders

Squamata (snakes and lizards)


Lizards live on the ground, burrows, trees or water
Snakes - have no limbs; kill prey by constriction or venom and swallowing whole

Chelonia (turtles)




Protected by a 2-part shell
(dorsal-carapace & ventral-plastron)
Some are aquatic, others are terrestrial
No teeth but powerful jaws w/ beak-like structure
Most are herbivores

Groups of Reptiles

4 orders (continued)

Crocodilia (crocodiles and alligators)




Crocodiles have long slender snouts
Alligators have short broad shouts
Fresh and salt water
4 chambered heart

Rhynchocephalia (tuatara)

Only survivor of primitive group of reptiles

Diversity of Reptiles

Lizards

Includes the largest lizard, the Komodo Dragon


Snakes
Includes rattlesnakes, copperheads, water moccasins,
& coral snakes

Diversity of Reptiles

Turtles and tortoises

Carapace(Dorsal) Plastron(Ventral)
The only with hinged shells


Crocodilians
The only Reptiles with
4 chambered hearts

Diversity of Reptiles



Snakes feed in a variety of ways:
Constrictors kill prey by suffocation
Venomous snakes kill prey by poisoning

Most snakes simply grab prey and swallow it whole

Diversity of Reptiles



Reptiles have special sense organs:
“Pit” of rattlesnakes allows them to detect heat of warm-blooded prey
Jacobson’s organ in roof of snakes mouth allows them to detect odors brought in by forked tongue

Ecology of Reptiles
 Many are in danger because of loss of habitat
 Humans also hunt them for food, to sell as pets, for their skins, etc.
 Some are now protected

31.2: Birds
Pgs. 806-814

Pictures of Birds

Characteristics of Birds





Class Aves
Feathers, wings and thin hollow bones which allow for flight

Keel shaped sternum
4 chambered heart
Respiratory systems consist of: lungs, anterior and posterior air sacs
Endotherms (warm blooded)

Able to regulate their internal body temperature

Characteristics of Birds


Internal fertilization (sexual)

Amniotic eggs w/ hard shell

Incubate their eggs (keep at a consistent temperature)
Adaptations of birds


Feathered legs and feet of ptarmigans
Modified wings and feet of penguins


Large eyes, acute sense of hearing and sharp claws of owls
Long beaks of hummingbirds

What is a Bird?



Class Aves
Feathers, modified scales that provide insulation & flight
Wings, power provided by muscles attached to sternum
(breastbone)

What is a Bird?

Other adaptations for flight include hollow bones, high metabolism maintained by
4 chambered heart & air sacs

Endotherm, maintains a nearly constant body temperature that does not depend on environment

Form, Function, and Flight

Body Temperature Control

Birds are endotherms (animals that can generate their own body heat)


They have a high rate of metabolism compared to ectotherms (metabolism produces heat)
A bird’s feathers insulate its body enough to conserve most of its metabolic energy

Bird Feeding

The more food a bird eats, the more heat energy its metabolism can generate


For this reason, the phrase “eats like a bird” is quite misleading – birds are voracious eaters
A bird’s beak, or bill, is adapted to the type of food they eat

Bird Digestion



Bird Respiration
When a bird inhales, most air first enters large posterior air sacs in the body cavity and bones


The inhaled air then flows through the lungs in a series of small tubes
A complex system of air sacs and breathing tubes ensures that air flows into the air sacs and out through the lungs in a single direction
This constant, one way flow of oxygen-rich air helps birds maintain their high metabolic rate and generates enough energy for flight

Bird Circulation


Circulation
4 chambered hearts and two separate circulatory loops

Structure of Bird’s Heart
Domestic pigeon
Right atrium
Right ventricle Heart
Left atrium
Left ventricle
Complete division

Bird Excretion


Excretion
Similar to those of reptiles – white, pasty uric acid droppings

Bird Response




Response
Well developed sense organs
Well developed eyes that can see color
Excellent hearing


Reproduction in Birds


Bird eggs are amniotic eggs
They have hard outer shells
Most birds incubate their eggs until they hatch

Diversity of Birds

A bird’s lifestyle is determined by its type of beak and feet.

Diversity of Birds

Diversity of Birds