Lecture 9 RH - Amphibians

Question 1

What are the defining features of phylum chordata?

Answer 1

Dorsal, hollow nerve cord

Notochord

Pharyngeal slits

Postanal tail

Question 2

What is the distinguishing feature of all vertebrates?

Answer 2

The brain case

Question 3

What is the reasoning behind the brain case being the distinguishing feature between hagfishes and lampreys?

Answer 3

Hagfishes don’t have vertebrae but lampreys do. They are both vertebrates nevertheless

Question 4

Where did the amphibians and primitive amniotes arise from?

Answer 4

From the early tetrapods of the devonian period

Question 5

Is the tetrapod clade mono, para, or polyphyletic?

Answer 5

Monophyletic

Question 6

Where do all 5 chordate traits appear?

Answer 6

During embryonic life

Question 7

Why are some reptiles, birds, and mammals living in water?

Answer 7

Due to secondary adaptations to aquatic life

Question 8

What appeared in sarcopterygii?

Answer 8

Lungs

Tetrapod limbs

Question 9

What are sarcopterygii?

Answer 9

Lobe-finned fishes

Question 10

How do air breathing fishes use air to breathe?

Answer 10

Air breathing fishes gulp air and store it in a pocket of the oesophagus.

Question 11

Where did the lungs arise from in lunged fishes?

Answer 11

The lung formed from an outpocketing of the oesophagus

Question 12

How did tetrapod limbs arise?

Answer 12

Tetrapod limbs arised in a lineage of lobe-finned fishes in the devonian period 400mya

Question 13

What do the transitional species between fish and tetrapods show?

Answer 13

The transitional limbs, skull, neck, ribs, etc.

Question 14

What is the skeleton of amphibians made of?

Answer 14

Strong bony skeleton

Question 15

How many limbs and digits do amphibians have?

Answer 15

4 limbs and 4 digits per limb

Question 16

What does amphibian skin feel like?

Answer 16

Smooth and moist

Question 17

How do amphibians respire?

Answer 17

Lungs, skin, and/or gills

Question 18

Are amphibians homeothermic or poikilothermic?

Answer 18

They are ectothermic and poikilothermic

Question 19

How does fertilization happen in amphibians?

Answer 19

External fertilization in toads and frogs.

Internal fertilization in caecilians and salamanders

Question 20

Do amphibians have a cloaca?

Answer 20

Yes

Question 21

How are amphibians adapted to both terrestrial and aquatic life?

Answer 21

Most live close to water for some part of the life cycle (for example reproduction in toads and frogs)

Aquatic larvae with gills rely on living in water to survive

Respiration across skin that must be kept moist

Question 22

What is the double circulation system of tetrapods?

Answer 22

2 circuits of blood delivery:

Pulmonary circulation

Systemic circulation

Question 23

What variation of the double circulation system exists with amphibians?

Answer 23

Amphibians have a 3 chambered heart.

Septum between atria is absent in lungless salamanders

Septum is complete in anurans

Question 24

How do amphibians breathe?

Answer 24

Amphibians use positive pressure to force air into the lungs.

1) Lowering of mouth floor draws air through nostrils.
2) Nostrils are closed
3) Floor of mouth is raised forcing air into the lungs

Question 25

What are the kind of amphibians in order gymnophiona?

Answer 25

Caecilians - 173 species

Question 26

How many limbs do gymnophiona have?

Answer 26

no limbs

Question 27

What do gymnophiona look like?

Answer 27

No limbs Small or no eyes Mesodermic scales in skin

Question 28

Where do gymnophionas live?

Answer 28

Burrow in tropical forest soil and ponds.

Question 29

What do gymnophionas eat?

Answer 29

Worms and small invertebrates

Question 30

How do gymnophionas reproduce?

Answer 30

Some lay eggs and guard those eggs Some are viviparous

Question 31

What kind of amphibians are urodela?

Answer 31

Mostly salamanders and newts - about 550 species

Question 32

What are the anatomical features of urodela?

Answer 32

Made up of a body which consists of a head, trunk, and tail. Limbs are at a right angle with the body Most are less than 15cm long but can be up to 1.5m long

Question 33

What do urodela eat?

Answer 33

Carnivorous as larvae and as adults. They eatworms, small arthropods, and molluscs

Question 34

Is fertilization internal or external in urodelas?

Answer 34

Internal

Question 35

How does fertlization take place in urodelas?

Answer 35

Spermatophore is deposited inside of the female. Aquatic species lay eggs Terrestrial species have direct development

Question 36

What is paedomorphosis?

Answer 36

An evolutionary change in which larval features of an ancestor are retained to adulthood in the descendent. *The Axolotl is a salamander that retains larval gills and aquatic habit as an adult

Question 37

What kind of animals are contained within order anura?

Answer 37

Frogs Toads *Over 5200 species in 44 families

Question 38

What are the clear differences between toads and frogs?

Answer 38

Toads have thicker skin Toads are more terrestrial

Question 39

What mode of reproduction do anurans have?

Answer 39

External fertilization fertilizaed eggs develop into tadpoles. Tadpoles are herbivorous and adults are carnivorous

Question 40

What is the breeding and life cycle of frogs?

Answer 40

1) Sexually mature at 3 years of age. 2) Male clasps female and eggs are released as well as sperm 3) Eggs are surrounded by jelly coats 4) Fertilized eggs are cleaved 5) Embryo is nourished by yolk 6) Tadpole feeds on algae 7) Skinfold grows over external gil. Water exits through spiracle 8) Hindlimbs and then forelimbs emerge 9) Adult forms when tail shortens

Question 41

What are some adaptations for frogs' breeding and life cycle?

Answer 41

Some frogs have dorsal brooding pouches. Eg. male pouched frog in NSW and QLD. Female gastric breeding frogs (QLD) brood tadpoles in their stomach. Water-holding frog burrows during drought and creates water tight cocoon from shed skin, holds water of 1/3 body weight in bladder

Question 42

What is happening to anurans today?

Answer 42

Worldwide, frog populations are declining, becoming patchy, and going extinct

Question 43

What are some possible causes of declining frog populations?

Answer 43

Habitat loss Climate warming Acid rain Increased UV (lowering wter levels expose eggs to more UV) Disease Pollution Displacement by introduced species (eg cane toads) Harvest by humans for their skin or meant

Question 44

What kind of grouping are amphibians?

Answer 44

Monophyletic. Common ancestor is believed to be bony fish (osteolipis)

Question 45

Which amphibian orders are sister taxa?

Answer 45

Gymnophiona and urodela