Chapter 31 Reptiles and Birds Mrs. Rushing Biology 2

Nonvertebrate chordates Mammals Birds Reptiles Amphibians Fishes Nonvertebrate chordates Invertebrate ancestor

Reptiles Pgs. 797-805

What Is a Reptile? Body plan typical to that of other land vertebrates Well developed skull Backbone Tail Two limb girdles Four limbs

Characteristics of all Reptiles Vertebrate Dry, scaly skin where scales can be smooth or rough and most times shed Lungs Terrestrial eggs with several membranes **Enable reptiles to live their entire lives out of water

Reptilian skin Dry Often covered with thick, protective scales Smooth or rough Protection Helps prevent the loss of body water ***Dry waterproof skin has a disadvantage. Can you think of what this might be?

Body Temperature Control Ectotherms –Animal that relies in interactions with the environment to help it control body temperature. If they want to get warm they go into the sun and if they want to cool off they get out of the sun

Feeding Herbivores – Iguanas Long digestive systems enable them to breakdown plant material. Carnivores – snakes, crocs, and alligators Grab prey with their strong jaws and swalow most meals whole.

Respiration To exchange gases with the environment , reptiles have two efficient lungs or, in in the case of certain species of snake, one lung. Lungs are more spongy than amphibians for better exchange gases – reptiles can NOT exchange gases through skin

Circulation Closed, double loop heart system Loop one- brings blood to and from the lung Loop two- brings blood to and from the rest of the body 2 atria and either 1 or 2 ventricles Most reptiles don’t have a completed septum Crocs and gators have most developed hearts of living reptiles (much like a mammal heart)

The Structure of a Turtle’s Heart Section 31-1 Kidney Liver Heart Cloaca Lung Bladder Digestive tract To body Right atrium From lungs To lungs Left atrium From body Ventricle Incomplete division

Excretion Urine either contains ammonia or uric acid If mostly a water animal - ammonia (which is toxic) is excreted because it can be diluted If mostly a land animal – uric acid is excreted (a white paste because water is absorbed in cloaca) ****By eliminating wastes that contain little water, a reptile can conserve water.

Response Active during the day and have complex eyes and see color very well Many snakes have a very good sense of smell and some can detect heat and ground vibrations through bones in their skulls Nostrils and sensory organs on roof of mouth that can detect chemicals Simple ears with external eardrums and a single bone that conducts sound to the inner ear.

Movement Reptiles have legs with larger stronger limbs enabling them to: walk, run, burrow, swim, or climb May have rotated legs under the body to carry more weight Backbones of reptiles help accomplish most of their movement

Reproduction Internal fertilization in which male deposits sperm inside the female’s cloaca Most male reptiles have a penis After fertilization, the female’s reproductive system covers the embryo with several membranes and a leathery shell Most reptiles are oviparous, laying eggs that develop outside the mother’s body. By carrying her eggs within her body, eggs are protected and kept warm.

Amniotic egg Most important adaptation to life on land Four membranes surround the developing embryo: 1. amnion 2. yolk sac 3. chorion 4. allantois

The Amniotic Egg Section 31-1 -- -Amnion Embryo Allantois- The chorion regulates the transport of oxygen from the surface of the egg to the embryo and carbon dioxide, one product of respiration, in the opposite direction. This baglike structure contains a yolk that serves as a nutrient-rich food supply for the embryo. The amnion is a fluid-filled sac that surrounds and cushions the developing embryo. It produces a protected, watery environment. -- The allantois stores the waste produced by the embryo. It also serves as a respiratory organ. Chorion Yolk sac- Shell

Groups of Reptiles 1) Lizards and snakes ( Order Squamata) 2) Crocodilians – crocs, gators, caimans, and gavials (Order Crocodilia) Alligators live in fresh water while crocodiles live in fresh or salt water 3) Turtles and Tortoises (Order Testudines) Turtle lives in water; tortoises on land. Shell consists of dorsal carapace and ventral plastron. 4) Tuataras (Order Sphenodonta) Only living member. Lack external ears, scales, and have a third eye located on top of brain

Complete Section Assessment pg. 805 1-6 Reptile Review Complete Section Assessment pg. 805 1-6

Birds

Nonvertebrate chordates Mammals Birds Reptiles Amphibians Fishes Nonvertebrate chordates Invertebrate ancestor

Silent Spring Rachel Carson wrote the book Silent Spring in the 1960s. As the title suggests, she describes waking up on a spring morning, hearing none of the usual chirping of songbirds and wondering what happened to them. Carson’s book increased awareness of the use of pesticides in the environment. Unfortunately, one of the chemicals that had been used interfered with the formation of the shells of birds’ eggs.

With a partner, discuss and answer the questions that follow. 1. What effect would weak eggshells have on the population of birds? How might this cause a “silent spring”? 2. If you were a legislator, what would you do about the use of chemicals such as pesticides in our environment?

What is a bird? Reptilian-like animals Maintain a constant internal body temp. Outer covering of feathers 2 legs that are covered with scales and used for walking or perching Front limbs modified into wings Most of these features are adaptations for flight.

Feathers Single most important characteristic that separates birds from living reptiles and other living animals Made of protein Develop from pits in birds skin Help fly and to keep warm 2 types 1. Contour-provide lifting & balance needed for flight 2. Down-traps air close to body to keep warm

Form, Function, and Flight 1) Body Temperature Control Endotherms – can generate their own heat High metabolism – which produces heat Feathers insulate body

Form, Function, and Flight Adaptations enabling flight: 1. Highly efficient digestive, respiratory, and circulatory systems 2. Aerodynamic feathers and wings 3. Strong chest muscles

How does the bird’s skeletal system enable flight? Fused bones provide sturdy attachments for muscles. Cross bracing and air spaces in the bones make them strong and lightweight.

2) Feeding Pathway of food: mouth, esophagus, crop, stomach, gizzard, intestines, cloaca Any body heat must be regained by eating food. The more food a bird eats, the more energy its metabolism can generate. Small birds must eat more because they lose heat faster Beaks or bills are adapted to what type food they eat

Beaks or Bills Insect-eating birds have short, fine bills Seed –eaters have short, thick bills Carnivorous birds long, hooked bills to shred prey Long, thin bills gather nectar from flowers or probing soft mud for worms Large, long bills help to pick fruit from branches Long, flat bills grasp fish

Digestive System Birds have no teeth and cannot breakdown food by chewing. Have a crop that stores and moistens the food From crop moves to stomach. If they eat meat- have expandable area where large amounts of food can be stored If they eat insects or seeds-have a muscular organ called gizzard that helps breakdown food by grinding it Food moves from here to small intestine where food is absorbed into the body Wastes leaves the body through the cloaca

Anatomy of a Pigeon When a bird eats, 1 food moves down Brain Esophagus Lung When a bird eats, food moves down the esophagus and is stored in the crop. Heart 1 Crop Kidney Air sac Moistened food passes to the stomach, a two-part chamber. The first chamber secretes acid and enzymes. The partially digested food moves to the second chamber, the gizzard. Liver 2 First chamber of stomach Pancreas Large intestine Gizzard Small intestine Undigested food is excreted through the cloaca. Cloaca 5 The muscular walls of the gizzard squeeze the contents, while small stones grind the food. 3 As digestion continues, the food moves through the intestines. 4

3) Respiration When a bird inhales, most air enters a large posterior air sac in the body cavity and bones Air travels through a series of tubes in a single direction ensuring that lungs are constantly exposed to oxygen-rich air Helps maintain high metabolic rate to maintain body temperature and flight. As well as, allowing birds to fly at oxygen depleted high altitudes

4) Circulation Closed, double loop system Heart has 4 chambers with a complete septum dividing heart into left and right halves Pathway: Right atrium receives oxygen poor blood from body and pumps this blood to lungs Left atrium receives the oxygen rich blood and pumps this to body

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

5) Excretion Very similar to reptiles – nitrogenous waste is converted to uric acid, water is absorbed by body and a white paste is expelled from bird

6) Response Brain is relatively large for animal’s size Can see color very well Can hear quite well Taste and smell are NOT well developed

7) Movement Most birds fly – Which ones cannot?? Skeleton is changed slightly to help a bird fly – near collarbone, hollow bones making skeleton more rigid. Form sturdy frame for muscles needed for flight Large chest muscles that power the upward and downward wing strokes Muscles attach to keel that runs down breastbone

Birds have the following adaptations to flight Wings Feathers Strong chest muscles Efficient respiratory system Efficient circulatory system which are that also that power that provide that ensure Homologous to front limbs in other vertebrates Provide warmth Upward and downward wing strokes One-way flow of O2-rich air O2 distribution to body tissues

8) Reproduction Both male and female reproductive tracts open into the cloaca Sex organs, which are internal, often shrink in size when not breeding Mating birds press their cloacae together to transfer sperm to egg (some birds have penis) Bird eggs are amniotic with a harder shell than reptile eggs

How does a chick get out of its shell? When a chick is ready to hatch, it uses a small tooth on its bill to make a hole in the shell. After much poking and prodding the shell breaks open

Groups of Birds 30 different orders Largest is the perching birds – songbirds. There are over 5000species Other groups: Pelicans Parrots Birds of Prey – owls, eagles, hawks Cavity nesting birds – woodpeckers Herons Ostriches Penguins

Bird Review 1) Are birds ectotherms or endotherms? 2) What characteristics do birds have in common? 3) How are birds adapted for flight? Bonus: Are robins in Iowa year round?