Download Birds - Mayfield City Schools

Birds: An Adventure Into
Endothermy
Birds
• Flying machine all aspects of its anatomy
and physiology are integrated for:
• 1. Maintenance
• 2. Growth
• 3. Reproduction
BIRDS LIVE AN
ENERGETICALLY COSTLY LIFE!
The Class Aves
• Approximately 10,000 species
• 29 orders
• Distributed over the Earth
Aves - Characteristics
1. Bipedal vertebrate
2. Keratinized beaks present (all birds)
toothless
Shape of
bill adapted
for different
feeding
techniques.
https://www.youtube.com/watch?v=XzHQ5-lYvrk
3. Birds are endothermic!
• What does that mean?
– high body temperature
– Cost: 20-30 times more energy
4. Birds Lay eggs. Elaborate of all vertebrates
• Dedicated
parental care
• Monogamous
pair bonds
(some for life)
https://www.youtube.com/watch?v=o42C6ajjqWg
• Amniotic egg with much yolk and hard calcareous
shell.
• Incubation external.
• Sex determined by chromosomes
•Females are heterogametic.
4. Birds Lay eggs.
•
•
Precocial - young active at hatching
Altrical – young helpless and naked
• ALTRUISM
•
When parents get help in feeding and guarding
young by other adults who have not bred that
year.
• Seems contrary to “survival of fittest”
• But “altruistic” helpers must be closely related
to parents – so still helping genes get passed
one
5. Birds are the only animals with
feathers.
• Nearly all birds can fly
• flightless birds (ostriches and penguins)
did evolve from flying
ancestors.
( http://www.youtube.com/watch?v=A5kzxOtvCjc
3:15)
6. Forelimbs modified into
wings and hind legs
(covered in scales)
adapted for swimming,
perching and walking.
7. Larger developed brains
• Large cerebellum and optic lobes
• Able to learn-vocalizations, social behavior
• Syrinx-sound producing organ
• Complex navigation (magnetic fields)
• Color vision
•
https://www.youtube.com/watch?v=XjAcyTXRunY
FEATHERS !
• All birds are covered with feathers,
collectively called plumage
• The main component
of feathers is keratin, a flexible protein
http://www.youtube.com/watch?v=Y2yeNoDCcBg 1:50
Purpose
flight
• strong yet lightweight
• surface area needed
for aerodynamics
insulation
• trapping pockets of air to help birds
conserve their body heat
• Lab:
Dissection of
Feathers
Purpose …
•
•
•
•
•
signal their age
sex
social status
Species
identity to one
another
http://www.youtube.com/watch?v=L54bxm
Zy_NE
https://www.youtube.com/watch?v=lMbDjN
DD4cM
• Birds preen their
feathers/oil glands
Bristles
• specialized feathers perform a tactile function.
• found around the mouth or eyelids.
• Insect eater - act as funnels, helping the birds to
scoop insects out of the air.
• Owls - act as sensors of
nearby objects.
• Woodpeckers - act as a
filter for the dust produced
as they drill holes in trees.
Molting
• Feathers, like mammalian hair, are dead.
• Most adult birds molt gradually to avoid
bare spots.
• Penguins molt all at once.
• Lose and replace their
feathers—at least
once a year usually after mating
– Tail feathers lost in pairs in order to keep
balance
– Water birds lose plumage after mating grounded
Flight Adaptations
• Skeletal system
• Muscles
• Respiratory System
Bird Flight - Skeleton
• Lightweight sturdy skeleton. Vertebrae are
fused except in cervical and tail.
• Contain air cavities – make them lighter.
• Sternum bears a large, thin keel where
flight muscles are attached. (not in flightless birds)
• Elastic Furcula (fused clavicles) – stores
energy as it flexes when wings beat.
• Key forces- weight, lift, drag and thrust
Skeletal System
• Hallux present (rare among vertebrates)
- the first toe / points backwards
- perching / grasping
Bird Flight - Muscles
• 2 major flight muscles
– Pectoralis  depress wing in flight
– Supracoracoideus  raises wing in flight
– Both are attached to keel
• Goal: overcome force of gravity
• Key forces
– weight
– lift
– drag
– thrust
Ways to Fly
• Thermoclines/gliding
• Flapping flight
• No flight at all:
ratites - diverse group
of large flightless groups –
most now extinct
Respiration System
• Nostrils, tracheal
system, lungs and air
sacs
• Key: no residual air left
in lungs, more efficient
• Unidirectional air flow
• Two complete cycles
required to complete a
breathe
• HIGHLY efficient
Geese Flight: The Art of
Formation
• -save energy (up to 50%)
• -cancels wing turbulence (big birds)
Feeding
“Eat like a bird.”
Intense metabolism and
voracious eaters
• Food swallowed whole
• Prey upon:
– Insects – there is bird to eat every kind
– Worms, Mollusks, Crustaceous Fish, Frogs,
Reptiles and Mammals, as well as other Birds
– Nectar
• Euryphagons – wide eating
• Stenophagons – narrow eating
PROs
and
CONs
Digestive System Highlights
•
•
•
•
Birds process food rapidly.
Crop – enlargement of the esophagus –stores food
soften
Two chambered stomach
– A. proventriculus – secretes gastric juices
– B. gizzard – lined with keratinized plates for
grinding food. Birds also swallow objects to
help in grinding
H
I
S
T
O
R
Y
• Archaeopteryx
• 147 million year old
relative of modern
bird
• Fossil discovered
in1861 in Germany
• More reptilian-like
except for the
imprint of feathers
• Birds and Reptiles have…
– Skulls are similar
– Single middle ear bone – stapes
– Lower jaw composed of 5 or 6 bones
– Excrete their nitrogenous wastes of uric acid
– Lay similar yolked-eggs
• Feathers evolved
from reptilian scales,
bird feet / still scales