Amphibians and reptiles

Amphibians and reptiles

• 2.
  Amphibians • Amphibians are animals that can live in water and have lungs and legs • Scientists think that amphibians evolved from ancestors of lungfish-like fishes • Most of today’s amphibians are frogs or salamanders
• 3.
  Characteristics of Amphibians •“Amphibian” means “double life” most live part of lives on land and part of lives in water • Amphibian eggs don’t have a shell to prevent water loss, so the embryos must develop in a wet environment • Are ectotherms body temp. depends on temp. of environment (cold blooded)
• 4.
  • Thin Skin – Skin is so thin that amphibians absorb water instead of drinking it – Can easily become dehydrated – Can breathe with lungs, but many absorb oxygen through their skin, which is full of blood vessels – May be bright colors; often to warn predator of poison
• 5.
  • Leading aDouble Life – Don’t just get bigger as they grow, they change form – After hatching, frog embryo becomes tadpole and must live in water • Gets oxygen through gills and uses tail to swim • Later, loses gills and develops limbs to live on land – Change from immature form to adult form is called metamorphosis
• 6.
  Kinds of Amphibians (1)Caecilians -look like earthworms or snakes, but have amphibian skin -do not have legs and have bony scales in their skin (2) Salamanders -do not develop as tadpoles -most lose gills and develop lungs -a few species keep gills and live in water for life
• 7.
  (3) Frogs andToads -90% of amphibians are frogs or toads -toads are a type of frogs (but spend less time in the water) (4) Singing Frogs -sing to communicate messages that help in attracting a mate or marking territories -most frogs that sing are males
• 8.
  • Amphibians asEcological Indicators – Unhealthy amphibians can be an early sign of changes in an ecosystem – Very sensitive to changes – Thin skin absorbs any chemicals in the water or air – Lungs take in chemicals from the air – Climate change also affects them because they are ectotherms
• 9.
  • Living onLand – 35 million years Reptiles after they first moved on land, some amphibians began to change thick, dry skin, legs were stronger, eggs did not dry out – They had become reptiles – Many reptiles are now extinct most famous are dinosaurs
• 10.
  • Characteristics ofReptiles – (1) Thick skin • Forms a watertight layer that keeps cells from losing water by evaporation • Cannot breathe through their skin • Depend only on lungs for oxygen (2) Body Temperature • Nearly all are ectotherms (cold blooded) • Most live in mild climates (3) The Amazing Amniotic Egg • Egg holds fluid that protects the embryo • Have a shell that keeps it from drying out
• 12.
  • Reptile Reproduction – Usually reproduce by internal fertilization – Reptiles do not go through metamorphosis – Female lays eggs when they hatch, the young look like small adults
• 13.
  • Kinds ofReptiles – Turtles and Tortoises • Tortoises live on land, turtles in the water • Unique because of their shells, which is used for protection Crocodiles and Alligators -spend most of their time in the water -eyes and nostrils are on top of their flat heads -crocodiles have a narrow head and pointed snout, and alligator has a broad head and rounded snout
• 14.
  – Snakes andLizards • Most common reptiles • Snakes can smell prey -Tuataras -live on only a few islands off the coast of New Zealand -do not have visible ear openings on outside of body -most active when temp. is low