1. Amphibians: the First Terrestrial Vertebrates

2. The Two Orders of Amphibians
Kingdom – Animalia
Phylum – Chordata
Class – Amphibia
Order – Caudata
Kingdom – Animalia
Phylum – Chordata
Class – Amphibia
Order - Anura

3. What is an Amphibian?
An animal that either moves back and forth between water and land or live one stage of life in water and the other on land.
Why do they need water?
Amphibians, and the majority of animals that came after, are tetrapods.
What is a tetrapod? Are humans tetrapods?

4. What Do Amphibians Eat?
Think about it, what else was on land at the time amphibians evolved?

5. Order Caudata: Salamanders
Have a tail throughout their whole life.
Most live either in caves or in moist forest floor litter and have aquatic larvae.
They lay eggs, sometimes on land, sometimes in water.

6. Salamander Reproduction
Salamanders reproduce sexually, but do not actually have sex!
The male deposits his sperm on the ground, a log, a leaf, etc. then the female lays in it and the sperm enter her cloaca.
Cloaca – a combination pee spot, poop spot, and vagina; i.e. it all comes out the same single opening

7. Order Anura: Frogs & Toads
Most live in moist environments
Larval form is called a tadpole.
Toads are more terrestrial than frogs.

9. Amphibian Adaptations
Amphibian skin has lots of
glands that secrete a mucous like substance that keeps them moist on land.
Males secrete a sticky substance that helps them cling to females during mating.
Some produce highly toxic chemicals as a defense mechanism. i.e., poison arrow frogs, cane toads

10. Feeding & the Digestive System

11. Nervous & Sensory Functions
Amphibians are ectotherms, meaning that their blood temperature is the same temperature as their environment.
Vision is well developed; amphibians are sight feeders.
Amphibians have clear lower lids called the nictitating membrane
Smell is very developed; they find mates mostly by smell
Hearing is also well-developed; frogs hear much the same as we do
Tympanic membrane is the equivalent of our ear drum

12. Reproduction, Development, & Metamorphosis
Development is tied to moist habitats, usually water.
Warm temperatures during spring and summer are what induce breeding.
Breeding between frogs is known as amplexus and may last from 1 to 24 hours.