Our focus…Amphibians Quick Question #1 What are some major evolutionary changes between fish and amphibians?
Amphibian basics… • Definition: moist, glandular skin that lacks scales of reptiles. Complex life cycles. Lay eggs that are non-amniotic. • 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.
Tied to the water… • 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
Not stuck in the water… • Have lungs instead of gills • Have legs to support body weight • Improved heart to help deliver needed oxygen to muscles.
Explain in your own words how amphibians are the adapted to land but still need water. Quick Question #2
Types of Amphibians • Urodela ~ Salamanders • Anura ~ Frogs and Toads • Gymnophiona ~ Caecilians
Caecilians (Gymnophiona) • Legless amphibians
Salamanders (Urodela) • 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 and Toads (Anura) • Frogs have moist, smooth skin and have large hind legs • Toads have dry, bumpy skin and have short hind legs
Quick write everything you know about the life cycle of a frog Quick Question #3
How do they eat? • 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/watch?v=wXqK5QulbJ8
Digestion • 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.
Respiration • Through the mouth • Through the skin • Through gills or lungs • Frogs can also pass air through expandable vocal cords
Internal Transport • Three chambered heart • Improved heart to deliver more oxygen to walking muscles. • Tadpoles have a two-chambered heart
Compare and Contrast a fish heart and a amphibian heart Quick Question #4
Excretion • Use kidneys to eliminate wastes • Urine travels through tubes called ureters into the cloaca
Response: How does it survive? • 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
Reproduction • Oviparous with external fertilization • Many have internal fertilization and are either oviparous, ovoviviparous, or viviparous Amplexus Male Midwife Toad Surinam Toad http://video.nationalgeographic.com/video/animals/amphibians-animals/frogs-and-toads/frog_greentree_lifecycle/ http://video.nationalgeographic.com/video/animals/amphibians-animals/frogs-and-toads/frog_strawberrypoisondart_tadpole/