Transcript Amphibians - Green Local Schools

Amphibians
Chapter 40
Origins & Evolution of
Amphibians
Section 40.1
Adaptation to land
• Amphibian means “double life”
• Came out of the water to escape
predation & competition for food
– Need a strong bony endoskeleton to deal
with force of gravity
Characteristics of early
amphibians
• Oldest amphibian fossil is 370 myo
• Evolved from lobe-finned fish
– Four limbs homologous to pectoral &
pelvic fins of fish
– Similar skull & vertebrae
• some had gills and lungs
• More toes than modern
amphibians
Modern amphibians
• Metamorphosis
• Moist, thin skin with no scales
• Feet lacking claws & often
webbed
• Use skin, gills, & lungs to
breathe
• Eggs lack membrane or shells
• Eggs laid in water
• Fertilization externally
Diversification of amphibians
• Two main evolutionary lines
1. Modern amphibians
2. Ancestor of reptiles
• 4,500 species in 3 orders
1. Order Anura
2. Order Caudata
3. Order Gymnophiona
Order Anura
• Meaning “tail-less”
• Examples: frogs & toads
– “toad” = rough, bumpy skin
– “frog” = smooth, moist skin
• Adaptations for jumping
• Tadpole: swimming larvae
• Carnivores
Order Caudata
• Example: salamanders & newts
• Elongated bodies with moist skin and
long tails
• Live in moist places
• Carnivores
Order Gymnophiona
• Example: caecilian
• Legless & resemble small snakes
• Very small eyes, often blind
• Carnivores
•Video
3 Order Note Cards!
• Front Side = Order name & picture
• Back Side =
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Anura
Caudata
Gymnophiona
example organisms
Location of animal on Earth
Habitat/environment
Adaptations for life/ key characteristics
Fun fact!
Characteristics of
Amphibians
Section 40.2
External covering
• Skin = respiration & protection
• Mucous glands: supply lubricant to
keep skin moist & poison for protection
*Video - The Waxy Monkey Frog
Poison dart frogs
Internal anatomy
• Strong bony skeleton
– Needed for life on land (larger animals)
– Pectoral & pelvic girdles help support
• More developed internal anatomy
– Closer to humans!
– video
Male internal anatomy
a. Large intestine.
b. Small intestine.
1. Lung lobes.
2. Heart.
3. Liver lobes.
4. Gall bladder.
5. Stomach.
6. Small intestine.
7. Testis.
8. Fat body.
9. Urinary bladder.
Female internal anatomy
1. Liver lobes.
2. Heart.
3. Ovary with eggs.
4. Gall bladder.
5. Small intestine.
6. Stomach.
7. Oviduct.
Heart & circulatory system
• Two separate loops
1. Pulmonary circulation: blood from heart
to lungs & back to heart
2. Systemic circulation: blood from heart to
muscles & organs then back to the heart
Three chambered heart
1. Right atrium: where (deoxygenated)
blood leaves to go to the lungs
2. Left atrium: where oxygenated blood
enters from the lungs
3. Ventricle: main pumping chamber
1.
2.
3.
Respiration
• Larvae respire via gills and skin
• Adults respire via lungs and skin
– Pulmonary respiration: through lungs
– Cutaneous respiration: through skin
Digestive system
• All adults are carnivores
• Mouth
esophagus
stomach
liver
Gallbladder
sm. Intestine
lg. intestine
cloaca
vent
• New terms:
– Pyloric sphincter
– Duodenum
– Ileum
– Mesentery
Excretory system
• Two kidneys that filter
nitrogenous wastes from
the blood
• Urine flow:
– Kidneys  urinary ducts 
urinary bladder  cloaca
Nervous system
• Brain:
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Olfactory lobes
Cerebrum
Optic lobes
Cerebellum
Medulla oblongada
• Nerves
– 10 pair cranial nerves
– Spinal cord
– Spinal nerves
Sense organs
• Sight: light travels through nictitating
membrane (transparent movable
membrane covering the eyes)  eye
• Sound: travels through tympanic
membrane (eardrum)  columella
(small bone) inner ear (embedded in
skull)
Reproduction of Amphibians
Section 40.3
Reproductive System
• Males: sperm cells develop in testes
and leave thru cloaca
• Females: eggs produced in ovaries
– Eggs enlarge and burst thru ovary into
body cavity
– Coated with jelly-like material in
oviducts before leaving
thru cloaca
Life Cycle
• Eggs hatch into tadpoles a few days after
fertilization
• As the tadpole grows, it slowly changes from
an aquatic larvae to a swimming adult
• Legs grow from body
• Tail and gills disappear
• Mouth develops teeth and jaws
• Lungs become functional
•Thyroxine – hormone produced by thyroid
gland to stimulate metamorphosis
Life cycle
Courtship & fertilization
• Males croak to females in spring
• Amplexus: male embrace of female
during mating
– Once female releases eggs, male releases
sperm  direct external fertilization
video
Metamorphosis
• Tadpole  frog
Parental care
• Males often remain with eggs
for protection
• Example: Darwin’s frog puts
eggs in his vocal sac where
they hatch, go through
metamorphosis, and emerge
in the adults form
video
gol
Goliath Frog
Mudpuppy