Chapter 26 Reptiles and Birds Reptiles Skin is smooth and dry, covered in scales - PowerPoint Presentation

Chapter 26 Reptiles and Birds

Reptiles Skin is smooth and dry, covered in scales Helps prevent the evaporation of water from its body. First vertebrates with adaptations that enabled them to survive on land only.Conserving water is a major obstacle.Scales made of water-resistant protein called keratin, same as human hair, fingernails and bird feathers.Reptiles that have legs have them in a position to help them run quickly, as opposed to amphibians which have them located to help them swim better.Reptiles without legs have adapted movement to allow them to move quickly.

Energy Most reptiles are carnivores Eat insects when younger, then larger prey as they get larger. Most do not chew food, but tear off small enough pieces they can swallow whole.Enzymes in the stomach digest the food, but in reptiles it is a very slow process.

Circulatory system Closed circulatory system With the exception of crocodiles, all have a partially divided three chambered heart. Crocodiles have a four chamber heart Allows a greater separation of oxygen rich and oxygen poor blood.RespiratoryHave well developed lungs with a large surface area.Do not exchange gases through the skin so they do not need to remain moist. Inhale and exhale more frequently than amphibians, allowing them to fill their lungs with a larger volume of air.

Excretory System Adapted to conserve water from body waste Most of the water removed from the blood through the kidneys is returned to the tissue. Reptiles from dry climates excrete thick, pasty urine with very little water.Aquatic reptiles excrete all waste as a liquid.

Reptiles E ctotherms—control their body temperature by their behavior If they are cold they lay in the sun, if the are warm they lay in the shade.

Snakes Circulation—three-chambered heart adapted to animals which breathe using lungs. Sense—Tongue detects chemicals in the air which are detected by taste and smell receptors. Flexible jaw—may unhinge allowing them to swallow much larger prey.Skin is shed when the old skin is worn out or when it is to small.

Reptilian Life Cycle Fertilization is internal Male reptiles have specialized organs to introduce sperm directly into the females reproductive tract. This makes water unnecessary for the sperm and egg to come in contact with each other.Increases the chance of fertilization taking place.Female then lays between 8 and 100 eggs.Amphibians may lay thousands of eggs.Reptiles emerge from the shell and usually are left to defend for themselves

Reptile Eggs Amniotic Egg—an egg that provides nourishment to the embryo and protects the embryo while it develops in a terrestrial environment. Yolk—Food source for developing embryo Embryo— developing organism, connected to the yolk by a stalk.Amnion—A fluid filled sac that surrounds and cushions the embryoChorion– Surrounds the embryo, yolk and allantois, helps to regulate gas exchanges, commonly referred to as the egg white.Allantois—Membrane bound sac that stores waste and is the site of gas exchangeShell—Water proof covering, that may be soft and leathery or more rigid caused by calciumIs porous to allow oxygen and carbon dioxide through

Origins Reptiles emerged around 300 million years ago. Scientist originally thought reptiles emerged from amphibians, but more recently believe they may have evolved from lobe-finned fishes. Lobe-finned fishes had lungs and could crawl on land.A mass extinction took place 245 million years ago and killed out most of the reptiles.

Dinosaurs On earth from 245 million to 65 million years ago First dinosaur species where two legged reptiles about the size of a chicken. About 65 million years ago a mass extinction of dinosaurs occurred.Scientist believed this was due to climate changeThe extinction process took between 5 and 10 million years.Other scientist believe a catastrophic event not climate change killed off the dinosaurs, such as meteor crashing into earthThe extinction process in this scenario may have taken as few as 100,000 years.

Modern diversity of Reptiles Tuataras Only found on two small groups of islands off the coast of New Zealand .Are protected by the government, but are decline due to increased rat populations.Turtles and TortoisesOrder Chelonian, which includes tortoises, sea turtles and freshwater turtles.Tortoises live entirely on land (up to 150 years)Female sea turtles come onto to land to lay eggs, males seldom go on shore.Freshwater turtles, sun on rocks and shore, but feed in the water.ShellsTortoises have a rounded shell, unlike freshwater turtles, but both of their shells are a series of bony plates covered with hornlike scales.Sea Turtle have a flat, lightweight and leathery shell

Snakes and Lizards Order—Squamata Both are found throughout the world, excluding polar regionsSome reptiles are able to blend into their environment by changing the color of their skin. (Chameleon and Anoles)Some animals can drop their tails when a predator grabs it. (Skinks and Gecko)The tail will continue to wiggle distracting the predator, the skink or gecko tail will grow back quickly.Crocodiles, alligators, caimans and gavialsOrder—CrocadiliansHave a four chambered heartMore similar to dinosaurs and birds then other modern reptiles

Crocodile Narrow head Long snoutFound in the tropical regions of Africa, Asia, Australia and North and South AmericaAlligators and CaimansShort Broad SnoutsAlligators are found in Tropical regions of China and Southern United StatesCaimans are native to Central and South AmericaGavialsLong, slender snouts that widens at the tip of the snoutFound in India and Burma

Ecological Roles Snakes control rat and mice populations that feed on crops Lizards help control insect numbers Iguanas and skinks eat leafy green plantsMost reptiles are carnivores and will eat insects, worms, snails and mammals.Food SourceEaten by a variety of other animals, birds and even larger reptilesUnprotected young of sea turtles and alligators are easy prey Reptile BehaviorMost of a reptiles time is spent searching for food, adjusting their body temperature avoiding danger. CamouflageMake themselves appear larger Loud noises

Parenting After mating many reptiles lay eggs in the sand, soil or in rotting logs. Some place where they will stay warm. After the eggs are laid, most reptiles abandon the nest. Female alligators will cover and protect the nest until the eggs hatch, then the mother will haul them to water in her mouth where they will follow her for the next few weeks.Migrating parentsSome reptiles migrate during different stages of their life cycle.Every two to three years, sea turtles return to where they were born to lay their eggs.Green turtles travel 3340 km to lay there eggs.

Human uses Turtles are eaten as food as well as there eggs Reptile skin is used for making leather goods, such as belts and purses Reptiles are also kept as petsFrontiers in BiologySome snake venoms causes drops in blood pressure and then death, researchers are study to venom to see if it can be used to help people with high blood pressure.

Birds Movement and support Have thin skin covered with feathers Skin contains an oil gland that coats the feathers to make them waterproof.Feathers insulate the birds body as well as protect it from the weather and make them more aerodynamic.Feathers wear out and must be molted or removed once or twice a year.ScalesHave scales similar to a reptile that covers birds legs and feet.Feathers are modified from reptilian scales (both made of keratin)

Skeleton Bones are hollow making them lighter and less dense reducing the overall weight of the bird. Bird bones are very strong, even if they are hollow, due to cross braces or struts. Bones that are jointed together in mammals and reptiles may be fused in birds. The wishbone or furcular is an example of a fused bone, also the vertebrae and ribs are fused.MusclesAlthough the bones a very light, a birds muscles are fairly large and heavy.Chest or pectoral muscles make up 25% of a birds weight.Located on the sternum and used to move the birds wings.Skull Enlarged eyes sockets and toothless beak help reduce the weight of the skull

Feathers Contour Feathers Have stiff central staff with many side branches call barbs Each barb has interlocking barbules.Preening is zipping together the feathers that have come apart.Down Feathers Thick fluffy feathers that cover body of birdsHave short shafts with tufts of long fluffy barbsInsulate the bird by trapping warm air close to the body.

Energy and waste Birds are endothermic—they maintain a constant internal temperature. Have overlapping feathers that trap air and minimize the loss of body heat. Preen feathers with oil secreted from oil gland to prevent water from soaking into feathers.Have a more efficient respiratory, circulatory, excretory and digestive system than reptiles

Circulatory system Have a four chambered heart which allows oxygenation of blood to be more efficient. (This is a strong similarity to crocodiles) Has a rapid heart rate and high blood pressure, making circulation fast and efficient. Respiratory systemLungs are attached to a system of air sacs that extend into all parts of the body including the bones. This allows birds to obtain large amounts of oxygen.Birds respiratory system is unique in that air flows though the lungs in only one direction.

Digestive system Birds must digest large amounts of food to maintain body heat and generate enough energy for flight. Food and small rocks passes from mouth to esophagus The esophagus enlarges to form a crop, a storage area where the food will soften.As it moves to through the crop, it enters the gizzard where enzymes with the swallowed rocks grind the food into a pulp.Food travels to the intestines where the nutrients are absorbed.

4. Excretory System Birds bodies are adapted to conserve water from body waste Urine is excreted in a pasty form, similar to dry climate reptiles.Birds do not have a urinary bladder to store liquid waste. (Keeps them lighter)Shore birds have small salt-excreting glands above the eyes to remove excess salt from water.

Diet Birds will feed on almost anything, including seeds, insects, fish, small land animals and large dead decomposing animals. Many birds use their feet to grasp food. Beaks are used to tear food into smaller pieces or break food into small enough pieces to swallow.

Life Cycle A lot of time and energy is spent attracting mates, building nest and caring for young. Reproduction Most of the year male and female bird reproductive organs are greatly reduced in size.As nesting season approaches, hormones are released which cause the reproductive organs enlarge and begin functioning.Most male birds do not contain external reproductive structures, instead sperm are produced in internal testes, which are surrounded by air sacs to lower the body temperature. Sperm do not survive at warm temperatures.Most female birds have only one ovary.Internal fertilization takes place through the cloaca (where waste is excreted), located at the base of the birds tail. After the sperm has traveled and fertilized the egg, the egg travels through the oviduct where it is coated with albumin and calcium carbonate. The egg then passes through the cloaca when being laid.

Amniotic Egg Shell– is made of calcium carbonate and is very strong and still porous Shell membrane—thin membrane that prevents bacteria from entering. Chalaza—ropelike structure that connects the yolk to the chorion, offers addition supportAlbumin—egg white, provides addition nutrients to embryoYolk Sac membrane– holds yolk in placeYolk—main source of nutrients, where the embryo will developEmbryo—the starting of the baby birdAir Sac—at fat end of egg that allows for expansion and stores extra air.

Bird eggs Size Smallest laid by a humming bird and is smaller than a pea Largest laid by an ostrich, size of a grapefruit.IncubationSince birds are endothermic, eggs must be kept a constant warm temperature while the embryo developsSome birds sit on the eggs in a nest, some like penguins hold them on their feet.HatchingMany baby birds are helpless and depend entirely on their parents for food.Robins are poorly developed when they are born. The have few feathers and their eyes are closed. It take about two weeks for them to develop and leave the nest. Chickens are very well developed when they are born. They are born with feathers and can eat on their own with assistance.

Origins of birds Birds probably evolved from reptiles about 225 million years ago, during the Triassic period. Bird origins and difficult to determine, since bird bones and feathers do not fossilize well. There where flying reptiles known as pterosaurs that where similar to birds in flight and environmental niche, but to many differences to be classified as birds.Archaeopteryx—Earliest fossil to have feathers, dates back to the Jurassic period, 150 million years ago. Considered the first known bird, but more recent discoveries indicate that there were more types of birds during this time period.After dinosaurs died out, birds evolved rapidly.

Diversity of Birds Some scientist think birds should be classified as a reptiles, but the presence of feathers and the ability to fly keeps them in their class. Aves—Class of vertebrates that birds belong to. Small—6cm Cuban bee hummingbird weighing 2 gramsLarge—2.5m Ostrich weighing 136 kilogramsAt least 9000 species of birds, this makes it tough for taxonomist to classify birdsAre broke into 27 different ordersScientist use body structure, beak structure, foot structure, behavior and song to determine which order they belong to.

Ecological Roles Small birds such as hummingbirds help pollinate plants. Help disperse seeds, when they eat ripe fruits the seeds pass through their digestive system unharmed and are scattered in their waste. Eat large number of insects.Feed on dead animalsAre a food source for reptiles and mammals

Bird Behavior Compared to reptiles, birds have a large brain in relationship to their body. Mating Males establish a territory before mating season begins.Perching birds use songs to establish and defend territories, female birds are attracted to their male species by song.Male bower birds build elaborate nest to attract females, their nest become very large and are decorated.Birds build nest to lay eggs in.Nest are built out all types of materials, including hair, moss, leaves, mud and even aluminum foil.Nest can be found in trees, in the grass, house overhangs, tin cans etc.…Many birds return to the same spot every year to build their nest. MigrationSome birds remain in the same location year aroundOther birds migrate great distances each year, the rufous humming bird travels 2500 mile from Alaska to Central America each year. Birds use landmarks or the earths magnetic field to find their way back.

Human Uses Important food source for humans They are raised for their meat and eggs Down feathersUsed to make pillows, comforters and clothing.JewelryPets