Chapter 25: Amphibians

Question 1

What are some issues with moving from water to land?(3)

Answer 1

• oxygen is 20 times more abundant in air and diffuses much more rapidly through air
• Air is 1000 times less dense, provides less buoyancy than water, limbs and skeleton must support weight.
• Air fluctuates in temperature more rapidly than water.

Question 2

What are some things that early land animals had to solve that plants were faced with when they too moved to the land?(4)

Answer 2

• Water conservation, gas exchange, reproduction and dispersal, and the fact that water no longer buoyed them up against the pull of gravity.

Question 3

Animals evolved what of things to compensate transitioning from water to land. (4)

Answer 3

• waterproof external layers, internal gas exchange systems, ways of reproducing that do not involve water and strong support systems ( endoskeleton and exoskeleton) that allows them to move about on land.

Question 4

By the Devonian period what two major animal groups dominated land?

Answer 4

• Tetrapods : four legged terrestrial verts

- Arthropods

Question 5

Who were the first tetrapods?

Answer 5

Amphibians

Question 6

Amphibians are closely related to what group of fish?

Answer 6

• Eusthenopteron and Coelacanth

Question 7

Ichthyostega?

Answer 7

• first to intermediate between fish and amphibians

Question 8

When did the first true amphibians appear?

Answer 8

• Carboniferous Period

Question 9

What caused amphibians to arise during the Devonian period?

Answer 9

• freshwater environments were unstable and subject to frequent dry periods
• those that survived this period developed lungs and double circulation and vertebrate limbs

Question 10

Most require what kind of a habitat?

Answer 10

• moist

L> to protect skin and to enhance respiration across skin surface

Question 11

They are ectothermic meaning what?

Answer 11

• their temperature is determined by and varies with the environment

Question 12

Where must the eggs be shed?

Answer 12

in the water or in moist areas to prevent desiccation. Metamorphosis is usually present

Question 13

Important Characteristics:

• Usually ___ limbs.
• Forelimbs usually have ___ digits
• Their skin is smooth with many __ ad __.
• They have a __ chambered heart and __ circulation. What makes it up?

Answer 13

• four
• four
• glands (poison)
• pigmented
• 3
• double
• Sinus venosus, two artia, one ventricle, a conus arteriosus

Question 14

What do Mesonephric kindeys do?

Answer 14

• excrete urea as main nitrogenous waste

Question 15

How many cranial nerves do they have?

Answer 15

• 10

Question 16

Whats the story about the sexes?

Answer 16

• separate

Question 17

What kind of eggs do they have?

Answer 17

• Mesolecithal eggs, which contain a moderate amount of yolk
• They are predominantly oviparous