Lissamphibia Flashcards
Lissamphibia Synapomorphies
- Ear: papilla amphibiorum and papilla basilaris
- Green rods in eyes
- Pedicellate teeth
- Most skin with mucous glands
- Operculum-columella complex
- Columella (aka plectrum) from hyoid arch
- Levator bulbi
Gerobatrachus (Permian in age)
First in fossil record to have:
- pedicellate teeth
- Salamander features of ankle
- Frog-like head
Pedicellate teeth
Teeth can bend to release strain (but can break off and be replaced), due to uncalcified zone
- Pedicell = bone base
- In frogs: bicuspid (2 bumps/crests)
Early tetrapods used what for hearing?
Bone conduction, put head on ground to hear seismically
Amphibian ear
- Tympanum evolves multiple times
- Stapes = columella = hyomandibula
- Papilla amphibiorum
- Papilla basilaris
- Opercularis and operculum
- Opercularis and columellaris are muscles into the shoulder girdle
- Cannot use both systems (papillas) at the same time
Papilla amphibiorum (and its pathway for hearing)
- Sensors for low frequency sounds (>1000Hz, for other noises/predators)
- Opercularis: hearing via forelimb on the ground
- Operculum: relaxes to hear then can vibrate
Pathway: opercularis -> operculum -> through inner ear -> Papilla amphibiorum
Papilla basilaris (and its pathway for hearing)
- Sensor for high frequency sounds (communication, >1000Hz)
- Tympanum vibrates when high frequency sound
- Columellaris contracts for hearing (makes tympanum/columella unable to vibrate?)
Pathway: external ear to tympanum -> middle ear/columella -> inner ear -> Papilla basilaris
Amphibian skin glands
- Hedonic gland: pheromone production
- Full poison/granular gland: protection
- Mucous gland: helps keep skin moist
- Can have pelvic patches where tons of gas exchange occurs
Amphibian skin can be fluorescent or transparent
Fluorescence example: Red-eyed treefrog
- During day: cryptic (camo)
- Display colourful markings at night when active and calling, retinal green rods allow for frogs to see these patterns at night and recognize conspecifics and potentials mates
- At night: blue light that penetrates forest creates a green fluorescence that matches the sensitivity of the frog’s retinal red rods
Aposematically coloured frogs
- Obtain toxins from insects they eat and then concentrate them
Some amphibians are venomous
Casque-headed frog: has spikes under skin, but when threatened = pushes them out through poison glands in skin, skin rebounds eventually and heals
Anderson’s spiny crocodile newt: Also push spikes through skin to poison predator (defense mechanism), but on lateral side down its torso
Ringed caecilian: Ducts from glands in oral mucosa release the products of glands at bases of teeth of the upper and lower jaws = poison bite, predatory mechanism
Blood flow in Anuran heart: when lungs are being ventilated
- Completely separate oxy and deoxy when using lungs
- No septum in aorta
- Systemic veins deliver deoxy to left atrium
-Left and right pulmocutaneous arch bring deoxy blood to skin - Right pulmonary vein brings oxy blood to heart
- Left + right carotid arches and left + right systemic arches deliver oxy blood to tissues and head
Blood flow in Anuran heart: when lungs are not being ventilated (Swimming)
- Mixed blood from right atrium and vena cava pumped out to skin and tissues
- Avoids left atrium because the lungs are not in use
Biphasic life
Extended larval phase
Complete metamorphosis of an Anuran
Most amphibians undergo metamorphosis, but some undergo direct development.
1) Skin and muscles of the tail, lateral line system, and gills all degenerate. Lungs develop.
2) Dermal glands develop. Head flattens and mouth widens. Skeleton mineralizes. Intestine shortens. Skin and muscles of limbs grow.
3) Tail resorbs. Urea cycle activates. Tympanum forms. Extrinsic eye muscle grow, nictitating membrane forms (protects eye and keeps from drying out). Adult hemoglobin replaces larval hemoglobin. Tongue develops.
How is metamorphosis controlled?
- Starts with environmental cues
- Controlled by hormones of hypothalamus and pituitary gland
- Pituitary gland can produce prolactin or TSH depending on environmental cues
- TSH -> T3, T4 = metamorphosis, positive feedback loop