Amphibians

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Amphibians

• Chapter 40

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Origins Evolution of Amphibians

• Section 40.1

Food!
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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

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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

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Diversification of amphibians

• Two main evolutionary lines
• Modern amphibians
• Ancestor of reptiles
• 4,500 species in 3 orders
• Order Anura
• Order Caudata
• Order Gymnophiona

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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

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Order Anura

• Meaning tail-less
• Examples frogs toads
• toad rough, bumpy skin
• frog smooth, moist skin
• Adaptations for jumping
• Tadpole swimming larvae
• Carnivores

Video
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Order Caudata

• Example salamanders newts
• Elongated bodies with moist skin and long tails
• Live in moist places
• Carnivores

Video
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Order Gymnophiona

• Example caecilian
• Legless resemble small snakes
• Very small eyes, often blind
• Carnivores

Video
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3 Order Note Cards!

• Front Side Order name picture
• Back Side
• example organisms
• Location of animal on Earth
• Habitat/environment
• Adaptations for life/ key characteristics
• Fun fact!

Anura Caudata Gymnophiona
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Characteristics of Amphibians

• Section 40.2

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External covering

• Skin respiration protection
• Mucous glands supply lubricant to keep skin
  moist poison for protection

Poison dart frogs
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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

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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.

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Female internal anatomy

• 1. Liver lobes.
• 2. Heart.
• 3. Ovary with eggs.
• 4. Gall bladder.
• 5. Small intestine.
• 6. Stomach.
• 7. Oviduct.

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Heart circulatory system

• Two separate loops
• Pulmonary circulation blood from heart to lungs
  back to heart
• Systemic circulation blood from heart to muscles
  organs then back to the heart

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Three chambered heart

• Right atrium where (deoxygenated) blood enters
  the heart from the body
• 2. Left atrium where oxygenated blood enters
  from the lungs
• 3. Ventricle main pumping chamber

2.
1.
3.
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Path of blood

• Right atrium ? ventricle ? lungs (to pick up
  oxygen)? left atrium ? ventricle ? rest of body
  (to drop off oxygen)

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Respiration

• Larvae respire via gills and skin
• Adults respire via lungs and skin
• Pulmonary respiration through lungs
• Cutaneous respiration through skin

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Digestive system

• All adults are carnivores
• New terms
• Pyloric sphincter
• Duodenum
• Ileum
• Mesentery
• Cloaca
• Vent

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Excretory system

• Two kidneys that filter nitrogenous wastes from
  the blood
• Urine flow
• Kidneys ? urinary ducts ? urinary bladder ? cloaca

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Reproductive system

• Males
• Testes (sperm made here) ? sperm ducts ? cloaca
• Females
• Ovaries (eggs made here) ? oviducts ? uteri ?
  cloaca

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Nervous system

• Brain
• Olfactory lobes
• Cerebrum
• Optic lobes
• Cerebellum
• Medulla oblongada
• Nerves
• 10 pair cranial nerves
• Spinal cord
• Spinal nerves

Video
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Sense organs

• light travels through nictitating membrane
• transparent movable membrane covering the eyes
  while underwater
• Sound travels through tympanic membrane
  (eardrum) ? columella (small bone)? inner ear
  (embedded in skull)

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Reproduction of Amphibians

• Section 40.3

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Life cycle
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Courtship fertilization
Video

• Males croak to females in spring
• Amplexus male embrace of female during mating
• May last for days!
• Once female releases eggs, male releases sperm ?
  external fertilization

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Metamorphosis

• Tadpole ? frog

Video
The real one
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Parental care

• Males often remain with eggs for protection
• Example Darwins frog puts eggs in his vocal sac
  where they hatch, go through metamorphosis, and
  emerge in the adults form