Download Class Amphibia - T.R. Robinson High School

Class Amphibia
Chapter 25
Accommodations to land
1. Oxygen content: oxygen is 20x more
abundant in air and diffuses more rapidly
through air than water
2. Air density: provides little support against
gravity-had to develop strong limbs and
remodeled skeleton
3. Temperature regulation: air fluctuates more
than water does and therefore experience
more harsh and unpredictable conditions
4. Habitat diversity: variety of habitats provides
safe shelter for protection of young
Tetrapods
Group of vertebrates that includes
amphibians, reptiles, birds and mammals
Characteristics of modern amphibians
1. Usually 4 limbs (tetrapod)
2. Skin smooth and moist with many glands
3. 3 chambered heart (2 atria and one
ventricle)
4. Ectothermal
5. Sexes separate
6. Moderately yolky eggs with jellylike
membrane coverings
3 Orders
 Comprise more than 5400 species
1. Caecilians: Order Gymnophiona
1. Contains approximately 160 species of elongate,
limbless, burrowing creatures commonly called
caecilians
2. Occur in tropical forests of S. America, Africa, and SE
Asia
3. Posses a long slender body, small scales in the skin of
some, many vertibrae, long ribs, no limbs, and a
terminal anus
4. Eyes are small, and most species are totally blind as
adults
5. Special sensory tentacles on the snout
Caecilians
 Food consists mostly of
worms and small
invertebrates
 Fertilization is internal and
males have a protrusible
copulatory organ
 Eggs are usually deposited
in moist ground near water
 Larvae may be aquatic or
complete larval development
may occur in the egg
 In some species eggs are
carefully guarded during their
development in folds of the
body
Salamanders: Order Urodela
 Consists of tailed amphibians, approximately
500 species
 Occur in almost all northern temperate regions
of the work
 Most have limbs set at right angles to their body,
with forelimbs and hindlimbs of approximately
equal size
 Carnivorous both as larvae and adult, preying on
worms and small arthropods or mollusks
 Most eat only animals that are moving
 Ectothermic (cold blooded)
Salamander breeding
 Fertilized internally (a female recovers in her
cloaca a packet of sperm-spermatophoredeposited by a male on a leaf or stick
Red spotted newt
Aquatic larve
metamorphose
into a brightly
colored “red eft”
stage, which
remains on land
from 1-3 years
before
transforming
into a
secondarily
aquatic adult
Dusky salamander
Female dusky
salamander attending
eggs, which includes
rotating eggs and
protecting them from
fungal infections and
predation by various
arthropods and other
salamanders
Salamander respiration
 General amphibian condition of having the ability
to exchange oxygen and carbon dioxide across
their skin
Longtail salamander
Frogs and Toads: Order Anura
 More than 4840
species of frogs and
toads
A. Bullfrog, largest American
frog and the mainstay of the
frog-leg market
B. Green tree frog, inhabitant of
the swamps in SE USA
Frogs and Toads
 Smallest measures less
than 1cm in length-can be
covered by a dime
 Live in Cuba and Brazilian
rainforest
 Largest is the West
African Conraua goliath,
more than 30 cm long
from tip of nose to anus
 Eats rats and ducks
Frogs and Toads
 Toads
Have short legs
Stout bodies
Thick skins
Usually prominent warts
American toad feasts on insects, snails, and
earthworms
The rough skin contains numerous glands that
produce a milky fluid, providing excellent
protection from a variety of potential predators
African clawed frog
Frog has
been
introduced
to
California,
where it is
considered
a serious
pest
Eat or be eaten
 Snakes, aquatic birds, turtles, raccoons, and
humans prey on frogs
 Fish prey on tadpoles
 Frogs & toads in tropics are aggressive, jump
and bite at predators
 Most can inflate lungs so they are difficult to
swallow
 When held, they will leap violently, voiding its
urine
 Some have poison glands in their skin
Frog skin
 Frogs have 2 layers: Epidermis and dermis
Epidermis contains ketatin, a protein that provides
protection against abrasion and loss of water
Epidermis contains mucous glands secrete a protective
mucous waterproofing the skin surface
Serous glands produce a whitish watery poison highly
irritating to predators
All amphibians produce a skin poison, but its effects
vary from species to species and with different predators
Gray Tree frog
Cryptic
coloration: so
good that the
presence of this
frog usually is
disclosed only
at night by its
resonant
flutelike call
Respiration
Use 3 respiratory surfaces for gas
exchange in air
Skin (cutaneous breathing)
Mouth (buccal breathing)
Lungs
Frogs and toads are more dependent on
lung breathing than salamanders
Skin is important for gas exchange during
hibernation
Frogs are positive-pressure
breathers that fill their lungs
by forcing air into them
A. Floor of mouth is lowered,
drawing air in through nostrils
B. With nostrils closed and glottis
opened, the frog forces air
into its lungs by elevating floor
of mouth
C. Mouth cavity rhythmically
ventilates for a period
D. Lungs are emptied by
contraction of body wall
musculature and by elastic
recoil of lungs
Vocalization
 Both male and female frogs have vocal cords,
but those of males are much better developed
 Frog produces sound by passing air back and
forth over the vocal cords between the lungs and
a large pair of sacs (vocal pouches) in the floor
of the mouth
 Vocal pouches also serve as effective
resonators in males, which are used to attract
mates
Reproduction
Reproduction
Male green tree
frog clasps a larger
female during
breeding season.
Clasping is
maintained until
the female
deposits her eggs.
Like most tree
frogs, these are
capable of rapid
and marked color
changes. Male is
usually green and
has darkened
during mating
Reproduction
Female S American pygmy
marsupial frog carries
developing larvae in a
dorsal pouch
Reproduction
Female Surinam frog carries
eggs embedded in
specialized brooding
pouches on the dorsum;
froglets emerge and swim
away when development is
complete
Reproduction
Male poison arrow
frogs carry tadpoles
adhering to its back
Reproduction
Tadpoles of a male
Darwin’s frog develop
into froglets in its vocal
pouch.
When ready to emerge,
a froglet crawls into the
parent’s mouth, which
the parent opens to
allow the froglets to
escape