BIO Exam 4: Chordata IV (amphibians)

What is the critical innovation of tetrapods?

limbs

What is the critical innovation for Amniotes?

ambiotic egg

What is the critical innovation for the Class Mammalia?

hair and milk

What are the 4 adaptations and challenges of the transition from water to land of tetrapods?

1. Mostly made of water

2. Need strong density and support due to gravity

3. Greater temperature fluctuations

4. Abundant oxygen concentration 

What did tetrapods evolve from?

sacropterygian ancestor

What are some characteristics that evolved in the aquatic habitat that links to terrestrial adaptation?

• an air filled cavity connected to the pharynx (lungs)

• strong paired fins

• internal nares for chemoreceptors (connecting outside to inside)

What is the transition form from water to land called?

Tiktaalik

What is Tiktaalik?

an intermediate species between a lobed-fish (sacropterygii) and a tetrapod

What are the characteristics of the Class Amphibia?

• 4 limbs with skeletal frame

• lungs

• eyes, ears and nasal cavity for air sensory reception

• 3 chambered heart

• metamorphosis

• cutaneous respiration

• ectothermic

What does ectothermic mean?

body temperature fluctuates with the temperature of their surroundings

What does endothermic mean?

an organism that generates and maintains a stable internal body temperature through its own metabolic processes, independent of the external environment

What are the 3 orders of the Class Amphibia?

1. Caecilians

2. Salamanders

3. Frogs and Toads

Why are species in the Class Amphibia highly dependent on water?

in order to avoid dessication

What are the characteristics of the Order Caecillians?

• limbless and tail less

• fossorial (burrowing)

• unique sensory tentacle on head

What are the characteristics of the Order Salamanders?

• tailed

• all carnivores

• generally 4 limbs

• variation in respiration

What is Paedomorphosis?

the retention of larval characteristics; allows salamanders to sexually mature without going through metamorphosis

What are some characteristics of the Order Frogs and Toads?

• no tail in adult but tail present in larvae

• specialized for jumping

• dramatic metamorphosis changes

• males set territories and use courtship

• indicator species for environmental changes

What is the form and function of the Order Frog and Toads skin?

the skin is made of keratin, skin has chromatophores allowing them to change color, and poison glands

What is the form and function of the Order Frog and Toad skeleton?

stiff vertebral column, short-bodied with powerful muscles

What is the form and function of the Order Frog and Toad respiration?

respire by skin and lungs, positive-pressure breathers, vocal cords for sound production

What is the form and function of the Order Frog and Toad circulation?

closed circulatory system, 3 chambered heart 

What is the form and function of the Order Frogs and Toads feeding?

carnivorous, protrusible tongue, teeth to prevent prey from escaping

What is the form and function of the Order Frogs and Toads sensory functions?

strong olfactory, modified ears and eyes

What is the form and function of the Order Frogs and Toads reproduction (temperate)?

external fertilization, eggs laid in water, hinglegs appear during metamorphosis, lungs develop and the gills are reabsorbed

What is amplexus?

eggs are fertilized as they shed as the male clasps the female frog/toad

What is the form and function of the Order Frogs and Toads reproduction (tropical)?

lay eggs on top of material like floating leaves, parent care, direct development in some

What is unique about how a Surinam toad reproduces (tropical)?

tadpoles are developed on the skin pockets on the dorsal side and emerge as tiny adults