groups of amphibians

Question 1

Lissamphibia formerly the amphibia

Answer 1

• Have moist, scaleless skins - a major shared derived trait for tetrapoda
• About 7,700 extant species
• Contains three distinct lineages:
○ Caudata or urodela (salamanders) - tailed, moist skin not dry (how to tell apart from reptiles)
○ Anura (frogs and toads) - no tails
Gymnophiona (caecilians) - no legs

Question 2

• Caudata or urodela (695 spp.) - tailed amphibians

Answer 2

• Tailed amphibians or salamanders
• Mostly in the northern hemisphere - temperate
• Lungs reduced or absent - still have some gills
• Pedomorphosis common
○ External gills on sexually mature forms

Question 3

anura (6,742 spp)

Answer 3

• Tailless amphibians - frogs and toads 
	• Worldwide distribution, except Antarctica and extreme northern polar regions 
	• Hindlimbs modified for hopping or jumping 
	• Many populations are declining 
	• Ranids - frogs 
		○ Moist skin 
		○ Mainly jumpers 
	• Bufonids- toads 
Dry and warty skin

Question 4

• Gymnophiona (205 spp.)

Answer 4

• Also called apoda or caecillians 
	• Found in wet tropic habitats 
	• External annuli or rings like earthworms 
	• Many spp. Have dermal scales 
	• Have lungs, except two species 
	• No limbs or girdles 	• Basically a snake but wormy - with moist skin and less eyes, burrowers - that’s why eyes are reduced and they do not have digits or limbs to get them stuck 
Some developed scales
	• Most lack tails 
	• Fossorial and aquatic life styles 
	• Eyes reduced 
	•

Question 5

skin

Answer 5

• Skin is permable to H2O and gases
• Highly vascular
• Epidermis - dead outer covering
Dermis - living skin

Question 6

• Skin permeability

Answer 6

• Controls movement of sodium (absorbed) and urea (retained by skin)
  
  • Generally found in freshwater (tissues = low osmotic pressure)
  • high tolerance for changes in sodium levels
  • Anurans have also adapted to arid (desert) habitats
  • Show limited brackish water adaptation and no marine forms
  • Mucous keeps their body moist
  • Some have adapted to survive salt water - bufo halophilus or bufo arenarum - still prefer freshwater

Question 7

• Integument adaptations

- glands

Answer 7

• Skin is highly glandular
1. Mucus glands
○ Secretes mucopolysaccharides
2. Poison glands
• Neurotoxins (most) and hemotoxins (some)
• Secretions induce numbness and vomiting
• Adaptive to reduce predation
• Use aposematic (warning) coloration and unken reflex
3. Hedonic glands
• Secretions by males used to stimulate females - reproduction
•

Question 8

aposematic coloration types

Answer 8

• Use aposematic (warning) coloration
& Unken reflex
• Coloration can also provide mimicry:
• Batesian mimicry - a harmless species mimics a poisonous species
• Mullerian mimicry - two poisonous species mimic each other
•

Question 9

reduce water stress?

Answer 9

• Pelvic patch
○ A highly vascularized patch of skin in the pelvic region
○ Cutaneous water absorption- amphibians don’t drink
• Large urinary bladder
○ 20-30% of body mass
○ Hypoosmotic urine stored in bladder
• Lipid secretions
○ Spread over body - Oily protector
○ Produced by dermal glands in some tree frogs
○ Reduced water loss by 90%
• Excrete uric acid (nitrogenous waste) - rare (extract much of the water from their waste and excrete uric acid)
• Behavioral
○ Restrict activities to dawn, dusk, and rain
○ Body postures
• Estivation
○ During dry sessions- a form of torpor
Reduce metabolic rate and surface area prone to water loss