Amphibians

Classification Kingdom: Animalia Phylum: Chordata Subphylum Vertebrates Class: Amphibians Examples- frogs, toads, salamanders newts

The Link Amphibians are the link between aquatic fish & terrestrial animals. Amphibians -> Reptiles Have adaptations to move habitat from water to land “Amphibian” means “double life”

Aquatic Ties Larvae Gills Tails Algae eaters Herbivores Moist skin Will suffocate if can’t get rid of CO 2 and receive O 2 Adult Must lay eggs in H 2 O Lack outer shell

Costa Rica-Tree Frog Eggs

Terrestrial Ties Adults Lungs + Moist skin Legs Carnivores Insects/other amphibians More efficient heart

Evolution of an Amphibian 360 million years ago Evolved from lobed-fin fish Bones in pectoral (forearms) and pelvic fins (hind legs) Homologous structures Leg bones-stronger To support the body’s weight

Evolution of an Amphibian 1. Formation of rib cage protects internal organs

Evolution of an Amphibian 2. Lateral line (vibrations in H 2 O) evolved into Tympanic membrane (vibrations in air)

Evolution of an Amphibian 3. Eyelids & nictitating membrane Act like goggles for protection keep moisture in

Evolution of an Amphibian 4. Nares-detect air borne scents 5. 1 st amphibians on earth were large Due to no competition for food As the # of vertebrates on land went up/there was more competition for food, the smaller ones were the ones to survive

Traits of Amphibians 1. Metamorphosis- Meta = many Morphosis = change form Aquatic larvae goes through many changes to become a terrestrial adult

Traits of Amphibians 2. Cold-blooded-ectotherms Use environment to regulate temperature

Traits of Amphibians 3. External fertilization- Need H 2 O Jelly-coated Eggs No shells

Traits of Amphibians 4. Feet, if present, lack claws Often webbed

Traits of Amphibians 5. Moist porous skin Cutaneous Respiration In O 2 & H 2 O thru skin Out CO 2 & H 2 O thru skin

Traits of Amphibians 6. Also respire or also breath thru a pair of internal lungs.

Number of species 4500 different species of amphibians

Order Anura Means: tailless 3800 species of frogs & toads Lay jelly-coated eggs in H 2 O Tadpoles- compact bodies Tongue sticky, long

Let us watch…..

Anura Frog Smooth skin Jump= powerful hind legs Jump Live near H 2 O Toad Rough bumpy skin Poisonous glands Only walk Live on land (moist)

Poisonous Cane Toad Introduced as “pest management” for beetles and other insects but know are breeding out of control and due to poisonous skin are killing farm animals and pets that eat them.

Urodela 400 different species= salamanders& newts Long tails Elongated bodies Moist skin 4 limbs Lives in moist area Lay eggs in H 2 O Worldwide- except Australia

Apoda or Gymnophiona “legless” amphibians 160 species Ex/Caecilians 12” long Resembles a snake Lives in the tropics in dirt/soil Eat Insects Rarely seen~ borrows in soil

Caecilian:

Life of a Frog (Metamorphosis) Larvae (fish-like) Gills Fin-like tail 2 chamber heart like a fish Closed system 1 loop Primarily herbivores

Life of a Frog (Metamorphosis) Adult Lungs Legs Closed system 3 chamber heart 2 loop system Primarily carnivores

External covering/moist skin -two jobs 1. Respiration (cutaneous) thin, moist skin-if skin dries suffocation b/c increase CO 2 Most night- cooler, more moisture Mucus glands- more moisture

2. Protection Some poisonous Most secrete a foul tasting substance Skin-camouflaging Blends in with environment