18. Amphibians

Question 0

Conditions of move on land?

Answer 0

• Shallow inland seas, swamps, ponds

- Low dissolved O2

Question 1

When was the move on land?

Answer 1

Devonian (400 mya)

Question 2

Why move on land?

Answer 2

• Increase competition in water (small pools, so crowded)
• New food resources on land (arthropods, plants)
• No vertebrate predators on land

Question 3

Differences between land and water as relevant to life?

Answer 3

• Availability of water/moisture
• Density of medium
• Amount of oxygen
• Stability of temperature
• Amount of UV radiation

Question 4

Problems on land?

Answer 4

1. Water needed to prevent desiccation (gas exchange required a moist surface, often require water for fertilization & larval dvpmt)
2. Air is less dense than water (stronger skeletal support, muscles, more energy, more O2 brought in + distributed)
3. Air temperature more variable (body temperature fluctuates - need to modify bhvr and phys)
4. UV radiation more intense (need physical protection or change bhvr)

Question 5

Advantages of terrestrial respiration

Answer 5

1. Higher concentration of O2

2. Gases diffuse faster in air than water

Question 6

Lung evolution comes from…

Answer 6

Lobe-finned fishes

• 2 ventral pockets formed off esophagus
• Used as a supplemental respiratory device

Question 7

Tetrapod solution to density of air?

Answer 7

Stronger limbs, vertebral column, ribs

Question 8

In early tetrapods - tail?

Answer 8

Used for balance, not swimming

Question 9

Tetrapod solution to requirement of more energy for density of air?

Answer 9

• More efficient circulatory system (3+ chambered heart, double circuit of blood flow)

Question 10

Advantages of circulatory system in amphibians?

Answer 10

• Blood under higher pressure

Disadvantages: blood is mixed

Question 11

What is Boyle’s law?

Answer 11

In breathing, the more volume, the lower the pressure

- Diaphragm and ribs change volume of thoracic cavity

Question 12

Breathing in amphibian is a …. pressure breathing

Answer 12

Positive (humans –> negative)

Question 13

What is a positive pressure breathing in amphibians?

Answer 13

Inhalation is a 2 stroke process

1. Air drawn into nostrils while mouth & glottis closed
2. Nostrils close, glottis opens and air forced into lungs

Question 14

Reproduction of amphibians?

Answer 14

• Mostly oviparous
• Separate sexes
• Mostly external fertilization
• Little parental care

Question 15

Amphibians life stages?

Answer 15

1. Larvae
   - gills, 2 chambered heart, herbivorous, UNDERGO METAMORPHOSIS
2. Adults
   - lungs, 3 chambered heart, carnivorous

Question 16

3 types of amphibian diversity?

Answer 16

Salamenders (urodela)
Frogs and toads (anura)
Caecilians

Question 17

Most important characteristics of urodela (salamenders)?

Answer 17

• Some have internal fertilization

- Some never leave water

Question 18

Most important characteristics of frogs and toads? (anura)

Answer 18

• Largest group

- Loud courtship calls to females

Question 19

Most important characteristic of caecilians?

Answer 19

• Have lost appendages

Question 20

2 Parental investment strategies?

Answer 20

• Produce billions of offspirng, provide no care, hope some survive
• Produce 1 offspring, care for it until maturity

Question 21

Which of the following is an amphibian parental investment strategy?

1. Gastric brooding
2. Carry tadpoles on back
3. Feed larvae with unfertilized egg
4. Feed your skin to your young

Answer 21

ALL OF THE ABOVE