Lab IV (amphibians): Survey of the Amphibians

Question 1

Characteristics of the Amphibians

Skull

Jaw articulation and mouth type

Answer 1

• Jaw articulation is between articular (lower jaw) and quadrate bones (on skull)
• Large mouth with small (pedicellate) teeth in upper/both jaws
• Two internal nares open into anterior part of mouth cavity

Question 2

Characteristics of Amphibians

Skeleton

Answer 2

• Mostly bony; varying number of vertebrae with zygapophyses (extensions that join one vertebrae to the next)
• Varied body forms
• Usually four limbs (tetrapod), some legless

Question 3

Characteristics of Amphibians

Integument

Answer 3

• Smooth, moist skin with many glands (mostly mucous)
  
  • Some poisonous
  • Pigment cells (chromatophores) common and variable
• Thin outer layer of skin (epidermis) with keratinized (water-proof) outer surface

Question 4

Characteristics of Amphibians

Circulation and Respiration

Answer 4

• 3-chambered heart (2 atria, 1 ventricle), double circulation through heart, skin abundant with blood vessels
• Respiration by lungs, skin, and gills in some; larva with external gills (may persist)

Question 5

Characteristics of Amphibians

Heat regulation

Answer 5

• Ectothermy (cold-blooded)

Question 6

Characteristics of Amphibians

Excretion

Answer 6

• Done by paired kidneys
• Urea is main nitrogenous waste

Question 7

Characteristics of Amphibians

Reproduction

Answer 7

• Sexes are separate
  
  • Internal fertilization in salamanders and caecilians
  • External fertilization in frogs and toads
  • Mostly oviparous, some oviviparous (eggs develop without maternal investment and hatch internally) or viviparous (bear live young)
• Metamorphosis (immature animal to adult; change in body form and way of life) usually present

Question 8

Characteristics of Amphibians

Nervous and Sensory

Special sensory area in ear?

Answer 8

• Papilla amphiborium

Question 9

Integumentary Adaptations of Amphibians

Integumentary features?

Answer 9

• Highly vascularized dermis - supports respiratory function
• Estivation - successive molts retained to prevent water loss
• Water uptake through pelvic patches in anurans
• Very vascularized skin folds in hellbenders

Question 10

Integumentary Adaptations of Amphibians

Other adaptations of epidermis?

Answer 10

• Warts on anurans
• Horny epidermal claws on spadefoot toad
• Specialized glands - produce protective mucous and poisons
  
  • ​Usually milky in texture
  • Glands concentrated in strategic area - e.g., paratoid glands behind head in some toads and frogs, along backs of salamanders
  • Dorsolateral ridges on some frogs
• Accessory breeding structures - nuptial pads on one digit per forelimb
• Expanded fingertips of tree frogs produce sticky secretion that “glues” them to trees etc.
• Adaptive colouration
  
  • ​Anti-predation colouration
    
    • ​Cryptic/concealment - resembles background
  • Warning colouration
    
    • **​Aposematic **- noxious animals
    • Mimicry

Question 11

Metamorphosis

Process and changes that occur

Answer 11

• Eggs deposited in water, gill bearing larvae (salamanders) or tadpoles (anurans), metamorphosis at end of larval stage
• Morphological and physiological changes during metamorphosis are under hormonal control
  
  • Regression of gills, formation of lungs
  • Degeneration of tails
  • Develop limbs
  • Form dermal glands
  • Reorganize digestive tract (herbivore to carnivore)
  • Modify excretory system (ammonia waste to urea)
  • Loss of tail “fins” in some salamanders

Question 12

What is paedomorphosis?

What are the two different processes involved in thsi?

Answer 12

• Paedomorphosis = Possessing juvenile characteristics in later, older development. Most extreme form involves attainment of sexual maturity in animal that retains larval form for entire life. Accomplished via two different processes:
  
  • Neoteny: Retention of one or more larval/embryonic traits in otherwise adult body. Involves slowing down/stopping development of affected traits
  • Progenesis: Early development of gonads in morphologically juvenile stage. Involves speeding up development of reproductive system

Question 13

Order Caudata

Answer 13

• Subclass “Amphibia”
• Order Caudata (“tailed”, salamanders)
• Elongate
• Mostly four limbs
• Northern hemisphere
• Two important trends:
  
  • Paedomorphosis
  • Reduction of lungs

Question 14

Family Cryptobranchidae

Answer 14

• Order Caudata
• No external gills (adults)
• Lungs present
• Progenic and permanently aquatic
• Very flat head; lots of wrinkles on side of body (increases surface area for cutaneous respiration)

Question 15

Family Ambystomatidae

Answer 15

• Order Caudata
• Mole salamanders
• Tiger salamander and long-toed salamanders in Alberta
• Lungs in adults
• Gills in neotenic forms (neotony occurs)
• Lots of stripes, long toes

Question 16

Family Salamandridae

Answer 16

• Order Caudata
• Newts
• Stout-bodied
• Lungs only in adults
• Two metamorphic stages in some - aquatic larvae to terrestrial efts to aquatic adults
• Conical, tapering tail (long and thin)

Question 17

Family Proteidae

Answer 17

• Order Caudata
• Mudpuppies
• Lungs and external gills as adults
• Neotony = rule
• All aquatic
• No folds on side (unlike hellbender); tail fin fold; big head

Question 18

Family Plethodontidae

Answer 18

• Order Caudata
• Lungless salamders
• Lack lungs and gills as adults (respire entirely through skin)
• Lower jaw immovable; tongue protrudes for prey capture
• Highly terrestrial; live in caves
• Snake-like but with four limbs

Question 19

Family Amphipiumidae

Answer 19

• Order Caudata
• Amphiumas
• Elongate, possess lungs, lack functional gills
• Limbs reduced in size (but still present)
• Snake-like

Question 20

Family Sirenidae

Answer 20

• Order Caudata
• Siren
• Elongate, gills and lungs at maturity
• Hind limbs absent, front limbs reduced
• Progenic and aquatic

Question 21

Order Anura

Answer 21

• “Tailless”; frogs and toads

Question 22

Family Pipidae

Answer 22

• Tongueless, aquatic frogs
• Dorsoventrally flattened
• Thickwaists, heavy legs, large webbed hind feet
• Forefeet for feeding
• In lab, looks like it has black toenails

Question 23

Family Ranidae

Answer 23

• Order Anura
• True frogs
• Streamlined; pointed head, slim, webbed hind feet
• Hind legs for jumping
• Anteriorally attached tongues
• Large eyes
• Semi-aquatic

Question 24

Rana luteiventris

Answer 24

• Columbia spotted frog
• Family Ranidae

Question 25

Rana pipiens

Answer 25

• Northern leopard frog
• Family Ranidae

Question 26

Rana sylvatica

Answer 26

• Wood frog
• Family Ranidae

Question 27

Family Bufonidae

Answer 27

• True toads
• Stout bodies
• Large parotoid glands behind eyes
• Horizontal pupils

Question 28

Anaxyrus boreas

Answer 28

• Western toad
• Family Bufonidae

Question 29

Anaxyrus hemiophrys

Answer 29

• Canadian toad
• Family Bufonidae

Question 30

Family Pelobatidae

Answer 30

• Order Anura
• Spadefoot toads
• Crescent-shaped, horny projections on side of foot (for digging)
• Plains spadefoot toad in Alberta
• Bar on heel to dig with

Question 31

Family Hylidae

Answer 31

• Order Anura
• Tree frogs
• Slender, long legs, blunt head
• Arboreal
• Toes tipped with expanded discs
• No webbed feet; long toes
• Boreal chorus frog in Alberta

Question 32

Family Dendrobatidae

Answer 32

• Order Anura
• Bony plates on ends of digits
• Coloured, numerous poison glands

Question 33

Family Discoglossidae

Answer 33

• Order Anura
• Disc-like tongue; can’t protrude
• Wide mouth
• Eggs on back
• Firebelly and midwife toads

Question 34

Order Gymnophiona

Answer 34

• Legless amphibians, caecilians
• Legless, burrowing or aquatic
• Very reduced eyes
• Small scales within dermis
• Black
• “Tentacles” in grooves near maxilla