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
Changes in the circulatory system at metamorphosis
Larval amphibian: all mixed blood, EVERYWHERE
Adult: segregating blood flow, deoxy only in pulmocutaneous arteries, posterior vena cava, hepatic vein, and jugular veins
Caudata Synapomorphies
- Salamanders, Caudata = tails
- Fusion of some bones in digits 1 and 2 (thumb and forefinger)
- Operculum is fused to ear capsule
- Quadratojugals are absent (in face/jaw)
- 2nd ceratobranchial bone (gill arch support) lost at metamorphosis
Walking-trot gait of salamanders
- Diagonal gait, hand moving with opposite side of body’s foot
- Bends body left or right
Salamander family native to AB
- Ambystomatidae
Spermatophore
Male salamanders deposit spermatophores that contain a capsule of sperm supported on a gelatinous base. Females deposit their eggs onto it.
Transfer of pheromones by male salamanders during courtship
- Male may deposit pheromones onto female head from their chin or teeth
- Female may rub chin on male for pheromones to get ovulation started
- Male can wave tail to move pheromones in the air and display
Paedomorphosis
- May speed up maturation of body and slow down reproduction maturity
- is not neoteny, which retain juvenile somatic character, slow down maturation of body and allow reproductive maturity
Anura Synapomorphies
- 9 presacral vertebrae (short trunk)
- Urostyle (fusion of vertebrae, sacral + pelvic structure, rigidity for jumping)
- Ulna and radius fused
- Tibia and fibula fused
- Elongate ankles
- Fused bones in skull
Frogs and toads of AB
- Pelobatidae: Plans spade foot toad
- Bufonidae: Western toad, Great Plains toad, Canadian toad
- Hylidae: Boreal chorus frog
- Ranidae: Columbia spotted frog, Northern leopard frog, Wood frog
Anuran body form and locomotor specializations
Short forelimb and short hindlimb: walk-hopper-burrower
Long forelimb and short hindlimb: walker-hopper, hopper-burrower
Short forelimb and long hindlimb: hopper, swimmer
Long forelimb and long hindlimb: jumper, walker-jumper
Frog callings
- Mating calls, warning, distress calls (juvenile), can also be display + call
- Sounds made depend on how many other males are around (more males = more chucking)
Reproductive modes of anurans
Most: external fertilizers, but vary a lot in terms of where + how lay eggs
Parental care by anurans
- Lots of parental care
- Guarding eggs, transporting eggs, brooding in vocal sac, embedded in back, feeding/transporting/rescuing tadpoles
Body form and mouth structures of tadpoles reflect differences in habitat and diet
- Size and shape of head varies
- Primarily plant matter diet as a tadpole
- Surface feeder = phytoplankton and insects
- Bottom feeder = filtering sediment
- Midwater feeder = zooplankton
- Torrent dweller = sucking food off rocks?
- Terrestrial tadpole
- Buried feeder
How do terrestrial anurans project their tongues to capture prey?
- Tongue is attached at front of lower jaw and uses muscle of tongue attached to chin to propel tongue out
- Inertia is used to pull tongue out, then its dorsal surface attaches to prey
- Tongue is drawn back into mouth by. hyoglossus muscle from hyoid apparatus
- Retraction of the eyes assists in forcing the prey into the throat
Water uptake and loss in anurans - strategies
- Can press pelvic patch against moist substrate to absorb water
- Lipid/waxy skin to prevent water loss (waterproof skin)
- Light colour = reflect heat off = less water loss
- Behavioural: minimize SA by crouching to conserve water, frog then opens up and spreads itself out when environment is wet enough
How frogs can spread lipids from lipid glands in skin
- By a series of stereotyped movements
- Lipid secretion is concentrated in one area then it uses its hindlegs to spread the lipids over itself (funny kind of meme frog movement u’ve seen on vids)
Gymnophiona Synapomorphies
- Paired tentacle between eyes and nostril (bilaterally symmetrical)
- Two jaw-closing muscles
- Scales within skin (buried)
- Limbless, lack pectoral and pelvic girdles
- Phallodeum (intromittent organ = penis equivant) formed by cloacal wall
Skulls of Gymnophiona
Tight + fused skull
- Burrowing -> need top of head to be soild?
- Robust - varying patterns related to soil type and digging mode
Gymnophiona dual jaw-closing mechanism
- Large interhyoid muscle pulls down on the retroarticular process of mandible to forcefully close the jaw
- Mandibular adductor muscles inset on the lower jaw and function to close it, but because they lie beneath the skull roof, they are small and generate little force
Glands of Gymnophiona
- Poison glands
- Mucous glands
- Pouches of scales in scale pockets
Caecilian reproduction
- May be oviparous (eggs then hatch into aquatic larvae)
- May be viviparous, direct-developing species
Threats to Lissamphibia
- Habitat loss (#1 problem)
- Climate change (shifting faster than able to adapt)
- Pollution (absorb pollutants via skin, affects development, can also be hormone pollution i.e birth control)
- Disease
Chytridiomycosis
- Fungal infection embedded in skin
- Kills frogs before reproduction, very invasive
- Spreading well because of the warming climate
