Chapter 27: Aves Flashcards
What is Archaeopteryx?
- an animal that died 147 million years ago leaving an imprint at the bottom of a lagoon.
Similarities between birds and reptiles?(6)
- occipital condyle
- single middle ear bone, the stapes
- both have a lower jaw composed of 5 or 6 bones
- excrete nitrogenous waste as uric acid
- lay similar yoked eggs and embryo developing on the surface by shallow cleavage divisions
- feathers are modified scales
What physical characteristic distinguishes them from all other vertebrates?
- feathers
Birds anatomy is completely designed around what?
flight
What are some characteristics that reflect their ability to fly?(6)
- light bones
- wings for support and propulsion
- enhanced respiratory system
- high body temp
- rapid and efficient digestive system
- high pressure circulatory system
What are the two theories for the origin of flight?
- Arboreal (trees down)
- Cursorial (ground up)
Describe the Cursorial hypothesis!
- fast running animals with long tails sued their arms to keep balance while running. Increasing the surface area of outstretched arms could have helped
Describe the Aboreal hypothesis!
- animals sprung from branch to branch, favouring the evolution of lengthened metatarsals and backwards directed hallux to grasp them
- front limbs were for climbing (front limbs remained long)
- back limbs for leaping
What are Paleognathe’s?
- can they fly?
- size?
- other name?
- sternum description?
- speeds?
- pectoral muscles development?
- large flightless birds
ex: ostrich, kiwis and emus - also called ratite birds
- flat sternum and poorly developed pectoral muscles
- some can run up to 60 MPH
What are Neognathae’s?
- can they fly?
- sternum?
- pectoral muscles description!
- what are also included in this despite the answer to the first question!
- flying birds
- keeled sternum
- large pectoral muscles for flight
- does include flightless birds such as penguins
L> keel is lost reduces size of flight muscles
Aves ___ sweat glands, ____ is at the base of the tail.
- do not possess
- oil gland
What kind of cavities are in their bones?
- air cavities
Do they possess teeth?
- no
How many cranial nerves do they have?
12
How many chambers does their heart have? What acts as the dorsal aorta? (is this different in mammals?)
- 4
- right aortic arch ( in mammals its left)
Are their red blood cells nucleated?
- yes as are all other vertebrates up to this chapter
Do they have a bladder?
no
Do females possess two functioning ovaries?
- no only one and its the left one
Young can be classified in two ways what are they?
- precocial (active)- 3 Downy, open eyed, mobile on hatching, follows parents and is shown food.
- altricial (helpless)- naked, blind and helpless hatchling
Example of Precocial young?
Example of Altricial young?
- Ruffed Grouse Hatchling
2. House Sparrow hatchling
Females are heterogametic meaning what?
What of males?
Compare to human males?
- producing two types of gametes with respect to sex chromosomes. (WZ)
L> Males: ZZ
L> In humans males are heterogametic, XY
- What kind of feathers are used in flight?
- contour feathers
What is the function of Down feathers?
- conserve heat
What is the function of Powder-down feathers?
ex? (2)
- release talclike powder and helps water proof feathers
hawks and herons
What does Pneumatized mean? (think skeleton)
- bones are laced with air cavities
Whats the story on the weight of their bones and the appearance of their vertebrae?(exception?)
- light weight for flight
- most vertebrae are fused together except cervical
Large pectoralis muscles are for what?
- flight which depresses the wing in flight
Supraccoracoideus is the antagonistic muscle to what? (function?)
- to pectoralis
- it raises the wing
Why is their center of gravity low?
- resulting from the pectoralis and supracoracoideus muscles attaching to the sternum
What’s the deal with the their feet? Muscles ? No muscles? hmm
- they are devoid of them!
- consisting of bone, tendon, and tough scaly skin and this makes them resistant to freezing!
Describe the function of the toe-locking mechanism!
- prevents the bird from falling, even when asleep, also sued by birds of prey to grasp them
Are all bird beaks the same?
NOOOO
- they all are adapted for specialized feeding
Why are they voracious feeders?
- high metabolic rate
Which eats more: Small birds or large birds?
- small!
relative to body mass
Compare hummingbird and chicken food intake per day!
- hummingbirds eat up to 100% of their body weight per day, chickens only consume about 3.5%
Is their digestive tract slow, fast, mediocre?
- very fast!
- shrikes can digest a whole mouse in 3 hours!
Do they possess a gizzard and crop? If they do functions??
L> what’s the deal with their taste buds?
- yes and yes!
L> gizzard grinds food
L> crop for storage - very few of them!
Explain air flow in their respiratory system! (4 cycles)
- Inspiration 1: air goes through the trachea, pass through the lung with parabronchi and collects in posterior air sacs that act as reservoirs of fresh air.
- Expiration 1: air leaves the posterior air sacs, goes through the parabronchi
- Inspiration 2: collects in the anterior air sac
- Expiration 2: leaves the body!
Describe their excretory system!
- paired metanapehric kidneys(not as efficient as in mammals)
- salt glands (especially found in marine birds to compensate for weak solute concentrating ability of their kidneys) - gives them a constant runny nose!
Nervous and Sensory system:
- They have a ___ brain. What is poorly developed in birds? (part of the brain). Highly intelligent birds such as crows have large what?What portion of their brain is larger than what is seen in reptiles?
- Their extremely good vision and ability of some to see into the UV range is on account for what? ex?
- well developed brain
- Cerebral cortex
- larger cerebral hemispheres
- Cerebellum ( coordinating movements and balance)
-Large optic lobes
EX: owls can see 10 x better in dim light
EX: Hawks can see 8 times
What is the slightly concave lower surface of wings called?
- cambered
Once the angle of attack for flight gets to around 15 degrees stalling occurs but what can delay it?
- placing a wing slot around the leading edge, directing a layer of rapidly moving air across the upper wing surface
What are the two types of wing slots present in birds?
- Alula : group of small feathers on the thumb which provides a midwing slot
- Gaps between primary feathers: provides wing tip slots
Describe wings that have a high aspect ratio!
- wings that sweep back and taper to a slender tip, rather flat in section and lack wing tip slotting characteristic of elliptical wings.
(good for feeding during flight, long migrations as well)
What wing has low aspect ratio?
- Elliptical wings
L> ratio of length to average width - they have alula and primary gaps, helping them prevent from stalling during sharp turns, low speed flight and frequent landing and taking off.
Urine in birds passes from the ureters to what?
- cloaca (terminal part of digestive system)
Phagocytes?
- mobile ameboid cells of the blood that are efficient in birds in repairing wounds and destroying microorganisms
Describe ceca!
- found at the junction of the small intestine and the colon are paired ceca serving as fermentation chambers.
Mammals and Birds are the only endothermic vertebrates that have this in their blood?
- nucleated biconvex erythrocytes
Pygostyle?
- caudal vertebrae are fused into this (tail)
A wing carrying a given load can pass through the air at high speed with a __ angle of attack or at low speeds with a __ angle of attack.
- small
- larger
