Transcript Class: Amphibia

Our focus…Amphibians
• Definition: moist, glandular skin that lacks scales of
reptiles. Complex life cycles. Lay eggs that are nonamniotic.
• The smallest major group of vertebrates
• The transition in evolution from water to land (amphi
means both, bio means life). First vertebrates to invade
the land.
• Larvae are aquatic - gills
while adults are terrestrial breath through lungs and skin
• Eggs have no shells (water
prevents drying out).
• Sperm swim through water to
fertilize eggs
• Skin must stay moist
• Have lungs instead of
gills
• Have legs to support
body weight
• Improved heart to
help deliver needed
oxygen to muscles.
• Urodela ~ Salamanders
• Anura ~ Frogs and
Toads
• Gymnophiona ~
Caecilians
• Legless amphibians
• Keep their tails even as
adults to aid in
swimming
• Some are fully aquatic,
some live in moist
environments, some
switch back and forth
throughout their life
• Can regenerate limbs
• Frogs have moist, smooth skin and have large hind legs
• Toads have dry, bumpy skin and have short hind legs
• Tadpoles are filter feeding
herbivores
• Adult amphibians are
almost entirely carnivorous
• Jaws or long, sticky tongues
are used to catch prey
• http://www.youtube.com/wat
ch?v=wXqK5QulbJ8
• Mouth to esophagus to
stomach.
• Stomach connects with the
small intestine then large
intestine.
• At the end of the large
intestine is the cloaca, a
muscular cavity that stores
wastes until they are
expelled.
• Through the mouth
• Through the skin
• Through gills or lungs
• Frogs can also pass air through expandable vocal cords
• Three chambered heart
• Improved heart to deliver more oxygen to walking muscles.
• Tadpoles have a two-chambered heart
• Use kidneys to eliminate wastes
• Urine travels through tubes called ureters into the
cloaca
• Developed nervous system
• Really moveable eyes to detect moving insects
• Ears have no external sound collectors but can
distinguish between calls
• Clawless, soft-skinned…so they may be toxic with
warning colors
• Oviparous with external fertilization
• Many have internal fertilization and are either oviparous,
ovoviviparous, or viviparous
Amplexus
Surinam Toad
Male Midwife Toad
http://video.nationalgeographic.com/video/
animals/amphibians-animals/frogs-andtoads/frog_greentree_lifecycle/
http://video.nationalgeographic.com/video/
animals/amphibians-animals/frogs-andtoads/frog_strawberrypoisondart_tadpole/