L5 Bevan - Amphibians

Question 1

Describe why the lung sacks in amphibians evolved into being

Answer 1

• in response to inadequacy of gills due to poor O2 conditions
• some bony fish could supplement their gills via air sacs when O2 levels were low - temporarily breathing

Question 2

what kind of fish evolved jointed fins first?

Answer 2

lobe-finned fish

Question 3

How do lungfish breath?

Answer 3

They have both lungs and gills.

Can survive buried in mud when ponds dry up (inactive state can survive months)

Question 4

What are lungfish thought to have given rise to?

Answer 4

Amphibians –> Reptiles –> Birds and Mammals

Question 5

What is the closed relative found to proto tetrapod?

Answer 5

A Devonian fossil found on Ellesmere Island (Canada) showed an intermediate - pectoral girdle, fins separated from ocular bones and skull

Question 6

What is the advantage of the pectoral girdle and fins being separated from the ocular bones and skull?

Answer 6

Advantage of separation = feeding

• allows greater mobility
• enhanced by architecture of 2 occipital condyles and pressure of the atlas
• snout and jaws become elongated
• improved articulation of the jaw and expansion of the palate

Question 7

Give 4 advantages of terrestrial life

Answer 7

1. foraging above water
2. juvenile dispersal
3. escapes predators
4. new niches

Question 8

Give 4 consequences of terrestrial life

Answer 8

1. Smell
2. Reproduction
3. Circulation with multiple respiratory systems
4. Skeletal changes

Question 9

What skeletal changes would have to be made for terrestrial life?

Answer 9

1. suspension of the vertebral column + organs
2. reorganisation of the vertebral column
3. reorganisation of the skull
4. undulatory locomotion

Question 10

WHy must changes to the skeleton be done?

Answer 10

• now weight bearing
• movement is facilitated by limbs
• gills collapse in air therefore need lungs for gas exchange
• water loos via evaporation - caused kidneys to have to made concentrated urine for N excretion

Question 11

What change to the vertebrae allowed suspension of the VC?

Answer 11

Stronger zygapophyses

Question 12

What 2 phases of life do amphibians usually have?

Answer 12

1. free living aquatic developmental stage

2. terrestrial juvenile/adult stage

Question 13

What order does the Axolotl belong to and how does it change to adult hood?

Answer 13

Urodela

retains larval characteristics seen in adult forms

Question 14

What order are frogs and toads in?

Answer 14

Anura

an = without
uro = tail

Question 15

What family is the dark poison frog in, and why is it brightly coloured?

Answer 15

Dendrobatidae

Brightly coloured as a warning to animals to not eat it as its poisonous

Question 16

Describe the reproductive cycle of amphibians

Answer 16

1. external or internal fertilization
2. water or land
3. larvae or mini adults initially
4. parental care (often male)

Question 17

Do amphibians show any courtship behaviours?

Answer 17

Dimorphic - strong sexual selection