Ch.9/ch.12

Question 1

Temnospondyli

Answer 1

(temnein = cut, spondylos = vertebra)
• All had aquatic larvae; adults ranged in terrestrial-ness
• Basal forms retained lateral line system in adults

Chordata —> more adapted for land or aquatic

Lateral line not adapted for air —> more for aquatic life

Question 2

Temnospondyli within Tetrapoda

Answer 2

• Temnospondyli includes Lissamphibia and extinct stem amphibians
• Lissamphibians only amphibian group to survive end-Cretaceous mass extinction
• Split between Temnospondyli (amphibians) and Amniota (lizards, birds, mammals) during early Carboniferous (~355 Mya) both makeup class of living tetrapods today

370 million years ago—> very diverse for many years however only lissamphibia survived Permian extinction

Question 3

Temnospondyl characters

Answer 3

• remain Paired occipital condyles in amphibians (as opposed to reptiles fusing to 1)

• Incomplete palate (combination of bony and soft tissue, roof of mouth)
- Interpterygoid vacuities

• Columella present (very small)
• Transmitted vibrations between eardrum (middle eat complex) and inner ear

• Derived from hyoid arch (2nd pharyngeal arch) (separating from stuff, goes inside head to become what it does)

Question 4

Lissamphibia

Answer 4

Living caecilians, salamanders, and frogs

(lissos = smooth) “smooth skin”
• Caudata and Anura more closely related to each other than to Gymnophiona

• Permeable, moist skin with mucus and poison glands

• Adult forms are carnivorous

• Pedicellate teeth (true teeth)
- Tooth crown and base composed of mineralized dentine with unmineralized zone in between (replace teeth but a little diff than sharks do)

Question 5

Lissamphibian senses

Answer 5

• some have chemoreception

Sight
• Vision reduced in Gymnophiona (most spend time under dark water or burrows—> little light)
• Green rods – additional type of photoreceptor, sensitive to blue and violet light

Hearing
• Ossified columella (stapes) (connects outside world to inside of head directly. Large circle behind eyes is ear drum)
• Musculo-skeletal connections transmit vibrations to inner ear (front arms placed on ground, some sound lost through travelling body)
• Specialized receptors for both low and high frequencies (related to dependence of vocal communication, find mates, etc)

Question 6

Respiration and circulation

Answer 6

• Lungs
• Gills in larvae, some adults
• Cutaneous (skin)

• Circulation pathway differs when lungs are not used
- Oxygenated and deoxygenated blood mix during cutaneous respiration
- Left atrium not used

Question 7

Blood vessels differ with life stage

Answer 7

Larvae
• Have gills
• Blood vessels associated with pharyngeal arches 3-6 feed gills

Metamorphosed individuals
• Have lungs
• Blood vessels from pharyngeal arches differentiate into different major arteries
• during metamorphosis blood vessels rearrange sometimes adults have less of them

Question 8

Water balance

Answer 8

• Essential for cutaneous respiration (must keep moist. Can absorb water through skin, can still drink water)

• Aquatic amphibians constantly absorb water through their skin
- Must constantly excrete excess water via urine (kidneys always working to excrete water out, especially if too much absorbed)

• Terrestrial amphibians have adaptations for absorbing and retaining water
- Pelvic patches (always on ground to absorb water)
- ”Waterproofing” skin (fats, natural waxes, lipids form around skin, limits gas exchange)
- Behavioral choices (shade)

Question 9

Integumentary glands

Answer 9

Mucus glands
• Keep skin moist
• Protect skin from minor scrapes (layer over integumentary)
• May protect against pathogens (protect from infections)

Poison glands
• Generate toxins (on back mainly in frogs or head or head and back. Not all 100% lethal toxins, sometimes just tastes bad)
• Distribution of each differs around body

Question 10

Skin colouration: crypsis

Answer 10

Camouflage

Leaves, dead leaves, algae, eggs, bird poop

Question 11

Skin colouration: aposematic

Answer 11

• Warning to predators about toxicity
• Some toxins derived from eating toxic prey items
• Convergence in different groups of frogs

Also mimicry of these colours or patterns —> some toxic, some not.

Some get toxins from own body or from diet

Question 12

Skin pigmentation in tree frogs from Chornobyl

Answer 12

• Frogs within Chornobyl Exclusion zone darker than frogs outside
• Colouration tied more to past radiation levels than current radiation levels

Why did this happen?
• Melanin protects cells and DNA from radiation
- darker morph most likely already in species and they reproduced more than the lighter ones

Question 13

Gymnophiona characters

Answer 13

(gymnos = naked, ophis = snake)

• Eyes greatly reduced
• Sensory tentacles (extra chemo and mechano receptors)
• Limbs lost
• Solid skulls (due to lifestyle, burrowing)

Pounds or underground —> reduced light —> reduced eyes

Question 14

Gymnophiona reproduction

Answer 14

• Internal fertilization via male intromittent organ (transmits sperm to female)

• Parental care common (until can fend for self)

• Some are oviparous with direct development, some are oviparous with larval stage

• Most are viviparous (internal fertilization, stay in mother for early growth, young scrape oviduct to release nutrients and other secretions to eat)

• Some scrape tissue and lipid-rich secretions from lining of oviduct

• Some eat lipid-rich skin off the mother’s body after birth

Question 15

Caudata characters

Answer 15

(cauda = tail)

• Generalized body plan (typically tetrapods elongated body, short limbs, tail)
• Elongated body with legs similar
lengths
• Some taxa lose legs
• Walk via lateral undulations (propulsion, sideways movement)

Question 16

Paedomorphosis

Answer 16

• Paedomorphosis: the retention of juvenile characters by sexually mature adults

• Occurs due to changes in developmental timing
1) Progenesis: acceleration of sexual maturation (only sexual organs, rest normal speed)
2) Neoteny: delay/prolongation of organ system maturation (some structures slowed down and/or stay)

Question 17

Caudata reproduction

Answer 17

• Some have internal fertilization via transfer of spermatophore

• Some have external fertilization

• Some lay eggs in water that hatch into larval form

• Some lay eggs on land that hatch into adult form

• Viviparity rare

Question 18

Anura characters

Answer 18

(an = without oura = tail)

• Large eyes (most frogs), binocular vision on top of head
• Body shortened (compared to salamanders and Cael)
Part of this comes from urostyle

• Urostyle – fusion of posterior vertebrae (in front of pelvic region, more strength and stability)
• Hindlimbs elongated
• Tibia and fibula fused
• Digit I lost on front feet

Anura diversity
Some not good jumpers but ones that do have long legs = propulsion = good jump

Question 19

Anuran advertising calls

Answer 19

• known for their calls, each species is different
• diff calls lead to speciation b/c no longer recognize calls
• Males emit a call unique to their species
• Females only responsive to calls unique to their species
• Females evaluate the calls for tone, volume to choose a mate
• Calls can make males more vulnerable to predators

Ex: make pew noises b/c females like it more but it’s louder and like to do when many other males around to lessen predation, but if few males around do clicks which females still respond to

Question 20

Anura reproduction

Answer 20

• External fertilization is most common
• Internal fertilization known in some terrestrial species
• Some lay eggs directly in water
• Some build foam nests in or near
water for eggs
• Some dig isolated pools that fill with water

Debate if this is parental care or not

Question 21

Anura parental care

Answer 21

• Guarding
• Carrying
• Feeding

Question 22

Tadpole ecology

Answer 22

• Larval ecology distinctly different from adult ecology
• Tadpoles are (generally) aquatic filter feeders
• Not all tadpoles fill the same niche (terrestrial, surface or bottom feeders, buried feeder, torrent dweller0

Question 23

Anuran metamorphosis

Answer 23

• Ossification of skeleton (becomes increasingly mineralized)

• Changes to mouth and digestive tract (b/c diff diets)

• Development of dermal glands (lack integumentary glands, hedonic glands (mature only))

• Resorption of gills, development of lungs (gills become lungs, depends in peomorphsis)

• Resorption of tail, development of limbs

Question 24

Amphibian conservation

Answer 24

Amphibians in crisis
• >40% of living amphibian species threatened • Most for any group of vertebrates

Causes
• Climate change (warm + drying —> respiration)
• Habitat loss (climate change or human activity)
• Batrachochytrium fungi causing chytridiomycosis (pathogen that invades skin of amphibians and disrupts things)

Why are amphibians so vulnerable?
• Permeable skin
• Two distinct life-stages (depend of diff parts of environment)

Question 25

Key Concepts

Answer 25

• Temnospondyli was a diverse lineage of amphibians that evolved during the Paleozoic. Today, it is represented by three living lineages: Gymnophiona, Caudata, and Anura.

• Amphibians have moist permeable skin, with numerous glands, that permits gas, water, and ion exchange.

• Amphibians employ many reproductive strategies, but many have a multi-phase life history including a larval stage and metamorphosis to the adult form.

• Amphibian populations are in decline around the world, due to habitat loss, climate change, and fungal infections.