Amphibians Flashcards
What are 5 key derived features of amphibians
- Moist skin
- Hearing adapted for teresstrial and aquatic environs
- Vision
- Pedicellate teeth
- Levator bulbi muscle
Describe Amphibians skin
Smooth, moist, permeable (O2 + H2O) skin
Skin contains unique vasculature = very thin epidermis
As a result they are tied to aquatic environs to limit water loss
Describe amphibians hearing
Hearing → adapted for both terrestrial and aquatic environs
- Use separate regions of inner ear to detect lower and higher frequencies:
Papilla amphibiorum → frequencies below 10,000 Hz
Papilla basilaris → sensitive to higher frequencies inc. mate calls
Extra bone: Operculum columella → controversial function
Thought to transmit low freq sound from forelimbs and shoulders to the ear
dont need to remember specific names
Describe amphibians vision
**4 types of photoreceptors **
Thought that amphibians can see colour at light intensities where other verts can barely see anything!
Have green and rod photoreceptors (only red rods in most verts)
Describe amphibians teeth
Pedicellate teeth
- Pedical composed of dentine and separated by connective tissue, the dividing zone
- Important in understanding their evolution and phylogeny
- Function debated
Describe amphibians Levator bulbi muscle
Causes eyes to bulge forward
Important for feeding = enlarged buccal cavity
If eye is touched they can retract it to protect it
Describe the skeleton of the Anurans, why is it specialised?
(frogs/ toads)
- Unique skeleton
- Reduced in number of bones and areas of ossification
Highly specialised for jumping
- Elongated hind limbs and pelvis
- Reduction/ disappearance of tail
- Urostyle → fusion of sacral vertebrae = shock absorbing pelvis
- No/ very short ribs = allows to stiffen trunk, providing a solid path for the transmission of thrust from limbs
- Tibula and fibula fused = tibio-fibula
Describe the reproducive modes of the Anurans
The norm in temperate climates is tadpoles (aquatic and terrestrial stages) –> see pic
But, this is not the norm in tropical climates
Complex and diverse:
Traits e.g egg and clutch characteristics
Oviposition site
Larval development
Stage and size of hatchling
Parental care…
What are 2 reproductive patterns evident in the Anurans?
1) Higher diversity of reproductive modes in the tropics
2) Progression from aquatic to terrestrial which has lead to a range of life history adaptations
Why are Anuran terrestrial modes more common in warmer, wetter environments?
Basically, if it rains a lot, they can get away with laying eggs on land
But, if not enough rain they are tied to aquatic environs
= Low temp & humidity constrain the evolution of reproductive modes in temperate clades
2 hypotheses: predation and desiccation
Describe how predation pressure effects Anurans reproductive modes
- Strong predative pressure in aquatic environments
- Species laying on land had higher fitness as a result of decreased predation
- Thought to be the biggest factor in driving the reproductive evolution of Anurans
Describe how the risk of dessication effects Anurans reproductive modes
Trade off
Protection against desiccation
Convergent evolution:
Terrestrial reproduction increases parental care
Give 2 Anuran adaptations to the terrestrial environ
- Foam nests (protect eggs from desiccation and predation)
- Egg laying on leaves overhanging water (tadpoles drop into water after hatching)
Describe reproduction in the Caecilians
Internal fertilisation
3 reproductive modes:
1) Oviparous with free living aquatic larvae
2) Oviparous with direct development
3) Viviparous, both terrestrial and aquatic
What are the 3 genera of Amphibians
Anurans (frogs/toads)
Caecillians
Urodeles (newts/salamanders)
