Amphibians: the First Terrestrial Vertebrates

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

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?

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

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.

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

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

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. http://www.teachertube.com/view_video.php?viewkey=b35fe889db419691b472 Some produce highly toxic chemicals as a defense mechanism. i.e., poison arrow frogs, cane toads http://videos.howstuffworks.com/animal-planet/35776-weird-true-and-freaky-cane-toad-invades-australia-video.htm

Feeding & the Digestive System http://videos.howstuffworks.com/hsw/23876-frogs-frogs-mouths-video.htm

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

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.