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Amphibians

Amphibians. Chapter 40. Origins & Evolution of Amphibians. Section 40.1. Food!. 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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Amphibians

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  1. Amphibians Chapter 40

  2. Origins & Evolution of Amphibians Section 40.1 Food!

  3. 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

  4. 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

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

  6. 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

  7. Order Anura • Meaning “tail-less” • Examples: frogs & toads • “toad” = rough, bumpy skin • “frog” = smooth, moist skin • Adaptations for jumping • Tadpole: swimming larvae • Carnivores Video

  8. Order Caudata • Example: salamanders & newts • Elongated bodies with moist skin and long tails • Live in moist places • Carnivores Video

  9. Order Gymnophiona • Example: caecilian • Legless & resemble small snakes • Very small eyes, often blind • Carnivores Video

  10. 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

  11. Characteristics of Amphibians Section 40.2

  12. External covering • Skin = respiration & protection • Mucous glands: supply lubricant to keep skin moist & poison for protection Poison dart frogs

  13. 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

  14. 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.

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

  16. 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

  17. 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.

  18. Respiration • Larvae respire via gills and skin • Adults respire via lungs and skin • Pulmonary respiration: through lungs • Cutaneous respiration: through skin

  19. Digestive system • All adults are carnivores • New terms: • Pyloric sphincter: • Duodenum: • Ileum: • Mesentery: • Cloaca: • Vent:

  20. Excretory system • Two kidneys that filter nitrogenous wastes from the blood • Urine flow: • Kidneys  urinary ducts  urinary bladder  cloaca

  21. Nervous system • Brain: • Olfactory lobes • Cerebrum • Optic lobes • Cerebellum • Medulla oblongada • Nerves • 10 pair cranial nerves • Spinal cord • Spinal nerves Video

  22. 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)

  23. Reproduction of Amphibians Section 40.3

  24. Life cycle

  25. Video Courtship & fertilization • 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

  26. Metamorphosis • Tadpole  frog Video The real one

  27. 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

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