lab 12

Question 1

Homologous structure

Answer 1

• characteristic shared by 2+ species that’s similar bc of common ancestry
• may or may not have same func.
• e.g. human, whale, bat, cat all have similar forearm

Question 2

Analogous structures

Answer 2

• similar structures that serve same function, but not from CA
• convergent evolution
• e.g. flight/wings

Question 3

Phylogeny for birds and mammals

Answer 3

Amniotic Egg = teptiles, birds, mammals
Diapsid skull = reptiles and birds (mammals have synapsid skull)
Adaptions for flight = birds

Question 4

Pigeon classification

Answer 4

-Vertebrate specially adapted for flight
Kingdom: animalia
Phylum: chordata
Class: Aves
Fam.: Columbiformes
Genus: Columba
Species: C. livia
Subspecies: C. l. domestica

Question 5

Pigeon Skeleton

Answer 5

• large sternum/keel for flight muscles to attach to
• fused pectoral girdle/clavicle = wishbone –> also for flight muscle attachment
• Wings = 1 big, 2 small, lots of little bones –> little bones are all fused for flapping (won’t bend during downstrokes)
• flexible bones prevent them from breaking during pressures in flight
• no teeth

Question 6

Pigeon mass

Answer 6

• very light
• hollow bones
• pneumatic bones = major bone hollows with struts (air spaces connected to respiratory system)

Question 7

2 Major flight muscles

Answer 7

Pectoralis

• big, superficial
• origin: keel/sternum
• inserts @ underside of humerus
• depress wing (downstroke)

Supracoracoideus

• small, deep
• origin=sternum; insertion=topside(dorsal) of humerus
• goes over clavicle
• elevates the wing (upstroke)

Question 8

Respiratory system

Answer 8

• lung and air sacs allow flight to occur
• constant supply of air to lung and cuts down on weight
• no diaphragm
• lungs surrounded by 8-9 air sacs (not for gas exchange)

Question 9

Air flow

Answer 9

Inhale 1: abdominal air sac
Exhale 1: lungs for gas exchange
Inhale 2: forward (anterior) air sac
Exhale 2: CO2 is expelled

Question 10

Feathers

Answer 10

• Primary and seondary wing feathers = main flight feathers –> lost and regrown annually
• priamary feathers attach to digits
• some species only have color on their secondary coverts

Question 11

bird digestion

Answer 11

crop

• giant sac to hold food
• can stretch a lot

gizzard

• where food goes next to be crushed up in prep for digestion
• lots of muscles and tendons
• some birds eat small rocks to help with crushing seeds

Question 12

Reproductive organs

Answer 12

-Don’t need to reproduce during winter and fall, so they shrink reproductive organs to cut weight