Ch 34 Chordates - Amphibians Flashcards
Lobe-finned fishes include what two living groups?
1) Actinistia
2) Dipnoi
Actinistia and Dipnoi have some characteristics of what?
The hypothetical first terrestrial vertebrates
Latimeria
Lobe-finned fish within the Actinistia
Latimeria possessed what?
Paired fins at the end of appendages with internal body elements
Lungfish retain what?
A prominent notochord (but have well-developed vertebrae as well)
Do lungfish possess functional lungs?
Yes
Lungfish can withstand what?
Drying in their habitat
When conditions of their environment require it, lungfish can enter what?
Estivation
Estivation
A state of reduced physiological activity during drought
How long can lungfish remain in estivation?
7 to 8 months
Characteristics of estivation
1) Air-breathe
2) Lower heart rate
3) Retain urea and other wastes
4) Catabolize body (lose weight)
Tetrapods
Ancestrally terrestrial and four-limbed vertebrates
What is the earliest diverging living group of the tetrapods?
Amphibia
Benefit(s) for chordates on land
O2 is 20 times more concentrated in air than in water
Difficulties for chordates on land
1) Air is 1,000 times more dense than water
2) Air is 50 times less viscous than water
3) Air experiences far grater temperature extremes
4) Terrestrial environments comprise a much greater diversity of habitats than do marine environments
Three body forms of amphibians
1) Frogs
2) Salamanders
3) Caecilians
How many species of amphibians are there?
6,000
Modern amphibian skeletal system
Skeleton is mostly bone
How many limbs do most amphibians have?
Four
Characteristic of amphibian skin
Very moist
Function of amphibian skin
Functions in respiration
Salamanders
Tailed amphibians
Are all amphibians endotherms or ectotherms?
Ectotherms
What is the ancestral condition of the salamander life cycle?
Metamorphosis from aquatic larva to terrestrial adults
How are salamander eggs fertilized?
Internally via a spermatophore passed to the female
Spermatophore
A packet of sperm
Newt life cycle
Have an aquatic larva followed by a terrestrial juvenile stage then by a second adult aquatic stage
Paedomorphosis
The evolution of retention of larval characteristics into adulthood
Many salamanders achieve sexual maturity while retaining what?
External gills and an aquatic habitat
What allows for cutaneous respiration in all amphibians?
Extensive nets of blood vessels in the skin
At various life stages, salamanders may have what?
Gills, lungs, both, or neither
How do some salamanders capture prey
Via ballistic tongue projection
Anurans
Frogs and toads
How many species of anurans are there?
5,200
Anurans are primarily adapted for what kind of locomotion?
Jumping locomotion
How are anurans adapted for jumping locomotion?
1) Reduction of vertebrae
2) Fusion of bones
3) Elongation of bones
What protein toughens that outer skin layer of anurans?
The protein keratin
What limits water loss in the skin of anurans?
Mucous glands
What kind of glands function in defense in anurans?
Toxin glands
Anurans have what kind of circulatory system?
An efficient, closed circulatory system
How many chambers does the heart of an anuran have?
Three
Two circuits of anuran circulation
1) Pulmonary (lung) circuit
2) Systemic (body) circuit
Do anurans have internal or external fertilization?
External
Anurans deposit huge masses of eggs where?
In aquatic habitats
How long can the process of metamorphosis in anurans take?
2-3 years
Apodans
Caecilians
Caecilians
Elongated, limbless, burrowing amphibians
How many species of apodans exist?
170
