Amphibians Flashcards
Modern amphibians are called
What does it include
When did it appear and diversify
Lissamphibians
-anurans (frogs and toads)
-salamanders
Appeared Carboniferous
Diversified Permian
Temnospondyls
What modern characterisitc do they share with modern amphibians
Stem amphibians or stem lissamphibains
Four digits on fire limb.
Modern amphibians shared traits
-associated with freshwater, not marine
-transition from aquatic larval to terrestrial adult form within lifetime
-ectothermic
-adults (non-larval forms) are carnivorous
Skin of amphibians
-cutaneous respiration (through skin) is primary mode of respiration
-smooth, thin, glandular skin makes it moist and permeable, assists respiration and prevents animal from drying out
Structures in skin of amphibians
-mucous glands to keep skin moist
-poison glands or glandular glands
-pigment cells (chromatophores) : aposematic
Reproduction of amphibians
-even terrestrial forms rely on cool, moist habitats for reproduction
-non-amniotic egg=anamniotic egg: keeps amphibians tied to water
-larval forms are aquatic and breathe with gills, such as tadpoles
When do lungs (if present) appear in amphibians
Usually become active after metamorphosis
Three orders of amphibians
Salamanders (Urodela)
Caecilians (Gymnophiona)
Frogs and Toads (Anura)
> 7000 species total
Salamanders
-size
-habitat
-Manitoba species
<15cm typically
Moist, temperate regions
Blue spotted, eastern tiger, barred tiger, mudpuppy
Salamander locomotion
Serpentine fish-like movement when swimming or walking
Salamanders have a more ancestral body plan than forge or caecilians
Salamander reproduction
courtship and fertilization: most have no physical contact, yet have internal fertilization (90% of species have internal fertilization)
-male deposits spermatophore on substrate, female recovers spermatophore in cloaca
-some species: male mounts female during courtship but deposits spermatophore in habitat
-Oviparous: lay eggs in water, aquatic larvae hatch.
-terrestrial species deposit eggs under logs or in moist earth and some have direct development (no larval stage)
Ancestral form of salamander life cycle
Metamorphosis from aquatic larval to breeding stage terrestrial adults
Facultative metamorphosis
-depending on region or habitat conditions, adult tiger salamanders may live in aquatic “larval” form or in terrestrial form when sexually mature.
Paedomorphosis
Retention of juvenile characteristics in sexually mature adults
-some species of salamanders retain gills, aquatic lifestyle and other larval characteristics after sexual maturity
-no metamorphosis
Ex: mudpuppy (necturus)
Red spotted newt lifecycle
Two metamorphoses
- gilled larva
Metamorphosis - red eft: terrestrial juvenile that does not breed (1-3 years)
Metamorphosis - aquatic adult: breeding form (sexually mature)
Caecilians
-characterisitcs
-habitat
-elongated, limbless, burrowing animals, 12cm-1m, greatly reduced eyes: dark/ light perception, dermal fold (annuli)
-tropics
Smallest group of amphibians
Caecilians
Caecilian reproduction
-only order of amphibians to use internal insemination and fertilization exclusively (males have copulatory organ)
-some species are oviparous: eggs usually deposited in moist ground near water
-other species are viviparous
Some oviparous species of caecilians feed their young how?
Mother grow new layer of skin every 3 days for young to feed on when they emerge from egg
Frogs and Toads
-Habitat
-size
Worldwide distribution
Every continent except Antarctica
Frogs come in all sized, from tiny to giant lap size
Largest group of amphibians
Anurans
Frogs and toads
Typical Anuran life cycle
Young to be born as an aquatic tadpole, then metamorphose into adult, air breathing form
Frog and Toad diet
-invertebrates and even small vertebrates or even other frogs
How anurans eat
-large mouths
-projectile sticky tongues
-contraction of eye muscles helps push prey into throat
Frogs and toads jumping specialization
-Hind limbs form lever system that catapults animal into air (elongated hind limb)
-powerful pelvic fastened to vertebral column (pelvis and urostyle: rod of fused vertebrae make posterior half of trunk rigid)
-short rigid vertebral column
Strong, flexible pectoral girdle absorbs shock of landing
Body shape, limb length and webbed feet indications of locator motion of anurans
- Short forelimbs and short hind limbs are associated with burrowing
- Long fire limbs and long hind limbs are found in species that climb and leap
- Hind limbs that are distinctly longer than the fire limbs usually indicate that a species is a hopper if the webbing on the hind feet is limited
- If the animal has longer hind limbs and webbing, it indicates it is a swimmer
Three common families of frogs in North America
Ranidae- true forge (bullfrog)
Hylidae-tree frogs
Bufonidae-true toads: short legs, stout bodies, thick skin with warts that produce milt fluid to protect from predators
How do anurans survive the winter
- Rest on bottom of water body, lower metabolism and absorb oxygen through skin (green, mink and leopard frogs)
- Manitoba toads tunnel into loose soil or burrows to remain in micro habitat with temperature above their freezing point
- Some terrestrial species tolerate freezing: body tissues flood with glucose to act as antifreeze allowing them to survive about -10
Frogs and toad courtship
-males call loudly and frequently to attract females during spring
-males have vocal sacs that amplify their courtship or advertisement calls
Do frogs and toads have internal or external fertilization?
External: female lays eggs, and male deposits seminal fluid over eggs during amplexus (mating posture). Eggs expands with water into jelly-like mass, often attached to vegetation.
Do frogs take care of young?
-most forge abandon their eggs, but some species guard or carry them
-tropical fiefs more likely to lay eggs on leaves or carry eggs/tadpoles
Ex:
-South American marsupial frog females have dorsal pouch for tadpoles
-female Surinam frog Carrie’s eggs in dorsal pouches until froglets emerge
-make poison arrow frog Carries tadpoles on his back
-male Darwin frog Carries tadpoles in vocal pouch
How can frog embryos develop quicker?
Amphibian populations have declined worldwide due to….
-habitat loss and fragmentation: deforestation, loss of wetlands, separation of forest and water, roads
-climate change
-chemical contaminants
-disease
Chytridiomycosis
-infectious disease caused by a chytrid fungus, an aquatic pathogen that affects anurans (Bd) and salamanders (Bsal), which is even more deadly
-chytrid fungus contributed to decline of 501 species worldwide, 90 of those went extinct
-fungus originated in Asia, global pet trade and testing of pregnancy tests led to spread
How does Bd affect amphibians
-fungal spores that live in water penetrate skin of amphibians
-infect keratin-containing tissues, which mostly affect froglets or adult amphibians
-spores mature and form reproductive body, which branches through animals skin
-skin gets thicker and tougher and interferes with respiration and water and electrolyte balance, eventually causing death and heart failure
When can affected amphibians of Bd be allowed back into environment
When fungus is gone…
Panamanian golden toad are only found in captive breeding programs rn
Characteristics of amphibian biology that make them especially vulnerable to factors like climate change, habitat loss and disease…
Permeable skin (susceptible to drying out)
Dependency on aquatic habitats
