CHAPTER 11 SECTION 3
AMPHIBIANS
WHAT IS AN AMPHIBIAN?
• Examples: frog, salamanders, toads
• Vertebrate
• Ectotherm
• Early life spent in water
• Most amphibians spend their adulthood on land
• Return to water to reproduce
GROUPS OF AMPHIBIANS
• Two major groups
• Salamanders: keep their tails
• Frogs/Toads: lose their tails
REPRODUCTION AND DEVELOPMENT
• Amphibian: double life
• Eggs are fertilized internally in most salamanders
• Eggs are fertilized externally in most frog/toads
• Fertilized eggs develop in water, larvae emerge
from eggs, begin a free swimming, fishlike life
• Tadpole: larva of a frog or toad
• Salamander Metamorphosis
• Larvae look like adults and lose gills
• Less dramatic
FROG METAMORPHOSIS
LIVING ON LAND
• Respiratory and circulatory systems of adult
amphibians are adapted for life on land
• Adaptations for obtaining food and moving
• Obtaining Oxygen
• Amphibian larvae use gills to obtain oxygen in water
• Lose gills during metamorphosis
• Lungs
• Organs of air-breathing vertebrates in which oxygen gas and carbon
dioxide gas are exchanged
• Oxygen also exchanged through skin
CIRCULATORY SYSTEM
• Tadpole: Single loop and a heart
with two chambers (like a fish)
• Adult amphibians: two loops and
a heart with three chambers
• Atria: two upper chambers of a
heart that receive blood
• Oxygen rich and oxygen poor blood
• Ventricle: blood moves into
lower chamber pumps out to the
lungs and body
• Blood mixes here
OBTAINING FOOD
• Tadpoles: herbivores
• Salamanders, frogs, toads: carnivores
• Frog and toads wait for their prey to come
close
• Salamanders stalk and ambush their prey
• Frogs and toads have camouflage skin helps
obtain food and conceal from prey
MOVEMENT
• Adult amphibians
have strong skeletons
and muscular limbs
• Frogs and toads have
large legs for leaping
and can absorb shock
of landing
AMPHIBIANS IN DANGER
• Habitat: specific environment in which it lives
• Destruction of habitats is causing populations
of these animals to decrease
• Amphibians are sensitive to changes in
environment
• Delicate skin
• Eggs do not have shells