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

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

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

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

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

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

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

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

Characteristics of Amphibians Section 40.2

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

Internal anatomy Strong bony skeleton More developed internal anatomy 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 Pulmonary circulation: blood from heart to lungs & back to heart Systemic circulation: blood from heart to muscles & organs then back to the heart

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.

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 New terms: Pyloric sphincter: Duodenum: Ileum: Mesentery: Cloaca: Vent:

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

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

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

Life cycle

Courtship & fertilization 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

Metamorphosis Tadpole  frog Video The real one

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