Phylum: Chordata

Class: Aves(Birds)

Classification

Kingdom Animalia---Phylum Chordata------Subphylum Vertebrata---------Class Aves

Aviation = flight

Order: ApodiformaHummingbird

Tucan

Order:Falconiformes

Peregrine falcon

Order: Galliformes

Dove

Class: GaviiformesLoon

Penguins

Origin and Early Evolution

Evidence from fossils and studies of comparative anatomy indicates that birds evolved from reptilesTheir features and their fragile hollow bones do not preserve well.copyright cmassengale

Evolution of Birds (from reptiles)• Archaeopteryx - “ancient

wing” • Reptile like - Had teeth in

beak, bony tail, claws on wings

• Bird like = Had feathers, & fused collarbone (wishbone)

• Could not fly – could glide for glide short distances

Aves Characteristics1. Forelimbs modified into wings 2. Thin layer of epidermis; No sweat glands3. Feathers – made of keratin4. Hollow, lightweight bones 5. Endothermic6. Efficient respiration 7. Heart with a completely divided ventricle (4 chambers) 8. Scaled feet (birds are related to reptiles) 9. Furculum (wishbone)

Body PlanBilateral symmetryForelimbs modified into wingsBony skeleton with air pocketsBeak, no teethSingle bone in the middle earEndothermic

Skeleton

The sternum supports the large breast musclesThe humerus, ulna, and radius, along with the pectoral girdle and the sternum, support the wing.The pygostyle, the terminal vertebra of the spine, support the tail feathers, which also play an important role.

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Feather Types1. Contour feathers

Has a hollow quill, main shaft, and barbs, barbulesCovers, streamlines body, and allows flight; coloration

2. Down feathersLight and fluffyconserve heat (birds are endothermic)

3. Filoplume feathersHair-like/no known function

•Feathers are covered in oil to keep them water proof - "like water off a duck's back" - this oil is secreted from a preen gland

•Preening is a behavior that replaces the oil on feathers, and repairs broken links on the vanes

Feather Types

Feather Structure

Endothermy

Generate and regulate body heat internallyEnables birds to inhabit both cold and hot climateBody temperature ranges from 40- 46 degrees Celsius. To help conserve body heat, birds fluff out their feathers to insulation.

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Nervous System - response

Well develop sense organsA large brainCerebrum = thinking, decision making Cerebellum = coordinated movementMedulla oblongata = basic body process Optic lobes = visionOlfactory lobes = taste and smell

Respiration

Highly advanced respirationPosterior and anterior air sacs with tube in between

Continuous one way flow

2 functions of the lungsOxygenate tissueCooling (no sweat glands)

Nutrition

CarnivoresThere is a bird to hunt nearly every insect

OmnivoresNectar feedersHave specially developed beaks to accomplish feeding taskBirds can eat up to 100% of their weight in food every day

Digestion

No teeth/poorly developed salivary glands

Grinding occurs in the gizzardPebbles are swallowed by the bird to help the gizzard grind the food

Pharynx—Esophagus—Crop—Stomach—Gizzard—Intestines—Ceca(in herbivores only, ferments)—Rectum—Cloaca

Excretion

Paired metanephridic kidneysUrine is formed by filtration

Uric acid is formedAdvanced animals, because it has low solubility it can be excreted with little water loss

Salt glands aid in removing salt

Territoriality and CourtshipDuring the breeding season many male birds establish an area that they defend against other males of their species, a behavior called territoriality.The male then attempts to attract a female to share this territory.Once a territory is established most birds engage in a period of courtship, behavior that is designed to attract a mate.Many males attract females by means of their brightly colored feathers.Some males combine song with flight displays.

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ReproductionSexual reproduction

flamboyant coloration to attract mate

Monogamy is general rule in AvesSeasonalLifetime—swans, geese

Internal fertilizationBirds lack a penis, so cloaca must meetOviparous

Why Monogamy?

Provide food, it must be gatheredNeed for a nest

Eggs must be incubatedMales are chosen because they have secured a territory

Announced through song

Development

Direct developmentEggJuvenile—must be cared for Adult

Many baby birds are born helpless and without feathers. These baby birds require lots of care from their parents.

Some babies hatch with feathers and can follow their mom around, swim and eat on their own.

Movement•Flightless (ostrich, penguin…etc)

•Forelimbs modified for flight = wings

•Collarbones are fused making a strong base for flight muscles - fused bone is the furculum

•Air spaces make the bones light in weight

•Strong chest muscle attach to a keel of the sternum (breastbone)

What allows flight?

FeathersAir cavities in bones decrease densityBeaks rather then heavy jawsExtremely high metabolic rateLarge hearts and high-pressure circulationKeen visionExcellent neuromuscular coordination

Environmental Interaction

Occupy almost any habitat on earth9,000 species

Largest group of vertebrates except fishes

Almost half the species migratePredators, prey, scavengers,herbivores, omnivores

MigrationWhy migrate

Increases food availabilityBreedingAvoid predatorsReduce interspecies competition

Northern hemisphereBreedingsummers

Southern hemispherewinters

MigrationHow do birds migrate?

Many follow landmarks such as rivers, coastlines.It is thought that they may also use the earths magnetic fieldThe sun and the stars are also used as compass directors

Some can travel as far as 11,200 milesStimulus for migration

Long days stimulate gonads to grow, fat deposits to increase and the urge to migrate north.