Chapter 40 Amphibians
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Transcript of Chapter 40 Amphibians
Chapter 40Amphibians
Section 1Origin and Evolution of
Amphibians
Amphibians• Greek word meaning “double” and
“life”• Many amphibians spend part of
their life in water and part on land
Adaptation to Land• Most likely evolved from lobe-finned
fishes• Pre-adaptations- adaptations in an
ancestral group that allow a shift to new functions which are later favored by natural selection
Adaptation to Land• Lobe-finned fish ancestral
amphibians- appendages to walk• Had modified pouches in their
digestive tract that evolved into lungs• Had nostrils to help aid in breathing
on land
Characteristics of Early Amphibians
• Amphibians and lobe-finned fishes share many similarities: skull & vertebral column
• Sarcopterygian- extinct lobe-finned fish that is thought to be closely related to amphibians
Sarcopterygian
Diversification of Amphibians
• 4,500 species belonging to three orders
• Anura- frogs and toads• Caudata- salamanders• Gymnophiona- caecilians- legless
tropical amphibians
Modern Amphibians• Most change from aquatic larval
stage to a terrestrial adult form- metamorphosis
• Most have moist, thin skin with no scales
• Feet, if present, lack claws and often are webbed
Modern Amphibians• Most use gills, lungs, and skin
respiration• Eggs lack multi-cellular membranes
or shells. They are usually laid in water or in moist places and are usually fertilized externally
Order Anura• Frogs & toads• World-wide, except in polar climates
and a few oceanic islands• Either spend part of or entire live in
water• Toad- rough, bumpy skin• Frog- smooth, moist skin
Order Anura• Body adapted for jumping (long
muscular legs)• Adult anurans are carnivores• Have a sticky tongue to help capture
food• Return to water to reproduce• Tadpoles- fertilized eggs hatch into
swimming, tailed larva
Poison Dart Frog
Gray Tree Frog
Bull Frog
Leopard Frog
Cane Toad
American Toad
Order Caudata• Salamanders- elongated bodies,
long tails, and moist skin• Smallest are only a few centimeters
long, largest are over 4.5 feet• Aquatic and terrestrial species• Carnivores
Order Caudata• Most live in North America and
Central America• Some are lungless and breathe
through their skin• Some reproduce in water, while
others lay eggs on land
Order Caudata• Water reproduction- larval stage• Land reproduction- no larval stage• Internal fertilization• Some terrestrial species stay with
eggs until hatched
Spring Salamander
Dusky Salamander
Red-Spotted Newt
Spotted Salamander
Order Gymnophiona• Caecilian- legless amphibian-
resembles snakes• Found in tropical areas of Asia,
Africa, and South America• 12 inches to 4.5 feet• Often are blind because their eyes
are found under skin and bone
Order Gymnophiona• Rarely seen- little is known• Some burrow and some are
aquatic• Have teeth- eat worms and other
invertebrates
Order Gymnophiona• Internal fertilization• Some species lay eggs & some
are born live• Young use their jaws and teeth to
scrape secretions “uterine milk” from the walls of the female’s reproduction tract
Sagalla Caecilian
Purple Caecilian
REVIEW!!!• Name some characteristics that
are common to modern amphibians.
• Compare and contrast the three living orders of amphibians.