Chapter 27: Aves

Question 1

What is Archaeopteryx?

Answer 1

• an animal that died 147 million years ago leaving an imprint at the bottom of a lagoon.

Question 2

Similarities between birds and reptiles?(6)

Answer 2

• 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

Question 3

What physical characteristic distinguishes them from all other vertebrates?

Answer 3

• feathers

Question 4

Birds anatomy is completely designed around what?

Answer 4

flight

Question 5

What are some characteristics that reflect their ability to fly?(6)

Answer 5

• light bones
• wings for support and propulsion
• enhanced respiratory system
• high body temp
• rapid and efficient digestive system
• high pressure circulatory system

Question 6

What are the two theories for the origin of flight?

Answer 6

• Arboreal (trees down)

- Cursorial (ground up)

Question 7

Describe the Cursorial hypothesis!

Answer 7

• fast running animals with long tails sued their arms to keep balance while running. Increasing the surface area of outstretched arms could have helped

Question 8

Describe the Aboreal hypothesis!

Answer 8

• 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

Question 9

What are Paleognathe’s?

• can they fly?
• size?
• other name?
• sternum description?
• speeds?
• pectoral muscles development?

Answer 9

• 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

Question 10

What are Neognathae’s?

• can they fly?
• sternum?
• pectoral muscles description!
• what are also included in this despite the answer to the first question!

Answer 10

• 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

Question 11

Aves ___ sweat glands, ____ is at the base of the tail.

Answer 11

• do not possess

- oil gland

Question 12

What kind of cavities are in their bones?

Answer 12

• air cavities

Question 13

Do they possess teeth?

Answer 13

• no

Question 14

How many cranial nerves do they have?

Answer 14

12

Question 15

How many chambers does their heart have? What acts as the dorsal aorta? (is this different in mammals?)

Answer 15

• 4

- right aortic arch ( in mammals its left)

Question 16

Are their red blood cells nucleated?

Answer 16

• yes as are all other vertebrates up to this chapter

Question 17

Do they have a bladder?

Answer 17

no

Question 18

Do females possess two functioning ovaries?

Answer 18

• no only one and its the left one

Question 19

Young can be classified in two ways what are they?

Answer 19

1. precocial (active)- 3 Downy, open eyed, mobile on hatching, follows parents and is shown food.
2. altricial (helpless)- naked, blind and helpless hatchling

Question 20

Example of Precocial young?

Example of Altricial young?

Answer 20

1. Ruffed Grouse Hatchling

2. House Sparrow hatchling

Question 21

Females are heterogametic meaning what?
What of males?
Compare to human males?

Answer 21

• producing two types of gametes with respect to sex chromosomes. (WZ)
  L> Males: ZZ
  L> In humans males are heterogametic, XY

Question 22

• What kind of feathers are used in flight?

Answer 22

• contour feathers

Question 23

What is the function of Down feathers?

Answer 23

• conserve heat

Question 24

What is the function of Powder-down feathers?

ex? (2)

Answer 24

• release talclike powder and helps water proof feathers

hawks and herons

Question 25

What does Pneumatized mean? (think skeleton)

Answer 25

- bones are laced with air cavities

Question 26

Whats the story on the weight of their bones and the appearance of their vertebrae?(exception?)

Answer 26

- light weight for flight | - most vertebrae are fused together except cervical

Question 27

Large pectoralis muscles are for what?

Answer 27

- flight which depresses the wing in flight

Question 28

Supraccoracoideus is the antagonistic muscle to what? (function?)

Answer 28

- to pectoralis | - it raises the wing

Question 29

Why is their center of gravity low?

Answer 29

- resulting from the pectoralis and supracoracoideus muscles attaching to the sternum

Question 30

What's the deal with the their feet? Muscles ? No muscles? hmm

Answer 30

- they are devoid of them! | - consisting of bone, tendon, and tough scaly skin and this makes them resistant to freezing!

Question 31

Describe the function of the toe-locking mechanism!

Answer 31

- prevents the bird from falling, even when asleep, also sued by birds of prey to grasp them

Question 32

Are all bird beaks the same?

Answer 32

NOOOO | - they all are adapted for specialized feeding

Question 33

Why are they voracious feeders?

Answer 33

- high metabolic rate

Question 34

Which eats more: Small birds or large birds?

Answer 34

- small! | relative to body mass

Question 35

Compare hummingbird and chicken food intake per day!

Answer 35

- hummingbirds eat up to 100% of their body weight per day, chickens only consume about 3.5%

Question 36

Is their digestive tract slow, fast, mediocre?

Answer 36

- very fast! | - shrikes can digest a whole mouse in 3 hours!

Question 37

Do they possess a gizzard and crop? If they do functions?? | L> what's the deal with their taste buds?

Answer 37

- yes and yes! L> gizzard grinds food L> crop for storage - very few of them!

Question 38

Explain air flow in their respiratory system! (4 cycles)

Answer 38

- 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!

Question 39

Describe their excretory system!

Answer 39

- 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!

Question 40

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?

Answer 40

- 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

Question 41

What is the slightly concave lower surface of wings called?

Answer 41

- cambered

Question 42

Once the angle of attack for flight gets to around 15 degrees stalling occurs but what can delay it?

Answer 42

- placing a wing slot around the leading edge, directing a layer of rapidly moving air across the upper wing surface

Question 43

What are the two types of wing slots present in birds?

Answer 43

1. Alula : group of small feathers on the thumb which provides a midwing slot 2. Gaps between primary feathers: provides wing tip slots

Question 44

Describe wings that have a high aspect ratio!

Answer 44

- 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)

Question 45

What wing has low aspect ratio?

Answer 45

- 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.

Question 46

Urine in birds passes from the ureters to what?

Answer 46

- cloaca (terminal part of digestive system)

Question 47

Phagocytes?

Answer 47

- mobile ameboid cells of the blood that are efficient in birds in repairing wounds and destroying microorganisms

Question 48

Describe ceca!

Answer 48

- found at the junction of the small intestine and the colon are paired ceca serving as fermentation chambers.

Question 49

Mammals and Birds are the only endothermic vertebrates that have this in their blood?

Answer 49

- nucleated biconvex erythrocytes

Question 50

Pygostyle?

Answer 50

- caudal vertebrae are fused into this (tail)

Question 51

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.

Answer 51

- small | - larger