Lecture 31 Amphibians Flashcards

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1
Q

what are derived characters of tetrapods?

A
  • have some specific adaptations
  • four limbs, feet with digits
  • a neck, which allows separate movement of the head
  • fusion of the pelvic girdle to backbone
  • absence of gills (except some aquatic species)
  • ears for defecting airborne sounds
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2
Q

what are two groups of the extant tetrapods?

A
  • amphibia

- amniota

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3
Q

what was an early amphibian?

A

ichthyostega: ancient semi-terrestrial tetrapod which was an amphibian in build and habitat
- primitive fish-like traits: tail with fin rays, gills, more than five digits (terrestrial vertebrates were until recently thought to be descended from ancestors with 5 digits per limb)

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4
Q

what are derived traits of early amphibians?

A
  • amphibian skull structure
  • limbs attached to vertebrae (3 part pelvis)
  • weight bearing joints (wrists, elbows, knee, ankle)
  • lungs as a primary breathing apparatus
  • forelimbs for locomotion and tail for balance
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5
Q

what are characteristics of amphibians?

A
  • ectothermic

- buccal pump to inflate lungs

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6
Q

what makes a species ectothermic?

A
  • cold blooded
  • dont maintain their body temp through internal physiological processes – rely on environmental factors
  • low metabolic rate (low food and energy requirements)
  • require constant temperature environment or behavioural thermoregulation
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7
Q

what is the buccal pump?

A
  • air drawn into the oral/throat cavity through nostrils or mout
  • mouth and nostrils are sealed and cavity is contracted to force lungs into the mouth
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8
Q

what are characteristics of amphibians?

A
  • ectothermic
  • buccal pump to inflate lungs
  • three chambered heart (2 atria, 1 ventricle)
  • gills (in larvae, retained into adulthood by some salamanders)
  • life cycle tied to water
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9
Q

what is the buccal pump?

A
  • air drawn into the oral/throat cavity through nostrils or mout
  • mouth and nostrils are sealed and cavity is contracted to force lungs into the mouth
  • in amphibians this is the sole mean of inflating the lungs
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10
Q

what kind of fertilization do amphibians exhibit?

A

external, almost all are in water

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11
Q

what is the amphibian life cycle?

A

“amphibian” – both ways of life

  • refers to the metamorphosis of aquatic larva into terrestrial larvae
  • remains very fishlike, not fully adapted to land
  • most lay eggs in water
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12
Q

what are the three extant orders of amphibians

A
  • urodela: salamanders which have tails
  • anura: frogs and toads which lack tails in adult stages
  • apoda: includes caecilians which are legless and resemble worms
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13
Q

what is order anura?

A
  • lose tails in adult stage
  • long hind legs are modified for jumping but lack legs in early larval stage
  • vocal cords well developed
  • ear modified for reception of airborne sound waves
  • some spp exhibit parental care
  • toads differ from frogs in having poison glands behind eyes
  • most feed on algae as larvae and invertebrates, sometimes vertebrates in adults
  • frog tongue - attached in front of the mouth, hydraulic pressure
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14
Q

what is order Urodela?

A
  • salamanders and newts
  • superficially lizard like appearance
  • have tails as larvae and adults
  • larvae have external gills, some remain aquatic, some become terrestrial
  • typically lay eggs in water and have aquatic larvae but also great variation in lifecycles
  • walk rather than jump
  • legs set laterally, long backbone
  • move slowly on land with lateral movements – less energetically efficient
  • predators of invertebrates as larvae and adults
  • members of one genus can flick their tongues like frogs
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15
Q

what is order apoda?

A
  • caecilians
  • legless amphibians, superficially resemble worms or snakes
  • legless
  • tiny eyes, no hearing, thick skull, tiny sharp teeth
  • burrowers
  • all caecilians use internal fertilization
  • most are viviparous, some with maternal care
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16
Q

important to ecology

A
  • global biodiversity