Class Amphibia

Question 1

Adaptations of Amphibians that made it possible to explore terrestrial habitats

Answer 1

-Air-filled cavity functioned as a swim bladder
-paired internal nares functioned in chemoreception
-Bony elements of paired fins

Question 2

Origin of Tetrapods

Answer 2

Tetrapods evolved limbs in ancestral aquatic habitats prior to their move to land.
Bony elements in fins of ancient lobe-finned fishes resemble homologous structures of amphibian limbs.

Question 3

Three orders of Class Amphibia

Answer 3

Gymnophiona or Apoda - caecilians
Caudata or Urodela – salamanders
Anura – frogs and toads

Question 4

Describe Order Gymnophiona

Answer 4

Caecilians
Tropical
Look wormlike; burrow in soil and feed on worms and other soil invertebrates
Small eyes; small dermal scales, many vertebrae

Question 5

Reproduction of Order Gymnophiona

Answer 5

Internal fertilization
Lay eggs in moist areas and may brood them OR
Viviparity

Question 6

Describe Order Urodela

Answer 6

Salamanders
With tails; limbs at right angles to trunk
Mainly small (< 15 cm)
Some aquatic forms much larger!
Either aquatic or terrestrial through entire life

Question 7

Order Urodela
Life Cycle in aquatic species

Answer 7

lay clusters of eggs in water
Larvae aquatic
Fin-like tail
External gills

Question 8

Order Urodela
Life Cycle in terrestrial species

Answer 8

Completely terrestrial species deposit clusters of eggs in moist soil or under logs
Direct development
Many with parental care

Question 9

Explain Paedomorphosis in Order Urodela

Answer 9

Retention of juvenile characteristics in adult stage
Non-metamorphic species - retain gills, aquatic lifestyle and larval characteristics as an adult

Question 10

Describe Order Anura

Answer 10

Frogs and toads
Adults lack tails
Caudal vertebrae fuse into rod-like structure = urostyle
Hind legs long and muscular with webbed feet
Very diverse life histories

Question 11

Amphibian skin lacks fur, feathers, hair or scales but is highly glandular
The glands function to:

Answer 11

Keep skin moist/prevent drying
Produce sticky secretions used during mating
Produce toxic chemicals to discourage predators

Question 12

Anuran Skeleton
is specialized for

Answer 12

jumping and swimming
-Back legs highly modified forjumping
Longer bones; greater muscle attachment

Question 13

Amphibians use 3 respiratory surfaces for gas exchange in air, what are they?

Answer 13

Skin provides cutaneous breathing
Mouth provides buccal (buccopharyngeal) breathing
Lungs are usually present in adults

Question 14

What is Positive Pressure Breathing

Answer 14

Rib cage does not expand to draw air into the lung
Rhythmic throat movements gulp air and force it backward

Question 15

Sensory Functions
of amphibians

Answer 15

Many sensory receptors widely distributed over skin
Some are simple – bare nerve endings; respond to temperature, pain

Question 16

In amphibians, Chemoreceptors are found in:

Answer 16

Nasal epithelia
Mouth lining
Tongue
Skin

Question 17

Purpose of olfaction in amphibians

Answer 17

for mate recognition and food location/detecting noxious chemicals in food

Question 18

Auditory System in amphibians

Answer 18

well adapted to life on land
Transmits vibrations from substrate and, in frogs, from air
Components:
Tympanic membrane
Middle ear
Inner ear

Question 19

Reproduction in amphibians

Answer 19

Dioecious, with external fertilization
Eggs lack resistant covering – must by deposited in moist habitats

Question 20

In amphibians, how do parental care increases chance of survival of any one egg

Answer 20

Maternal care occurs in species with internal fertilization
Paternal care occurs in species with external fertilization