By: Cristian, Courtney, Kevin, and John

What is an Amphibian?

What is an Amphibian?An Amphibian is a vertebrae that, in some

exception, lives in water as a larva and on land as a adult, breathes with lungs as an adult, has moist skin that contains mucus glands, and lacks scales and claws.

Evolution of Amphibians Challenges faced by the transition from water to

land• Breath air• Protect themselves and their eggs from drying out• Support themselves from the pull of gravity Adaptations that helped amphibians live at

least part of their lives out of the water• Bones in limb and limb griddles became stronger,

which made movement more efficient• Lungs and breathing tubes enable them to breath

air• Sternum formed a bony shield to support and

protect internal organs.

Amphibians became the dominant form of life during the Carboniferous Period, also called Age of Amphibians.

Climate changes that made low, swampy habitats to disappear lead to the extinction of most amphibian groups by the Permian period.

The three orders of amphibians that survive today

• Frogs and Toads• Salamanders• Caecilians

Form and Function in AmphibiansClass AmphibiaFeeding• Tadpoles are typically filter-feeders or herbivores • Tadpoles intestines are long and coiled

• Intestine structure helps break down hard to digest plant material

• Intestines usually filled with food • As tadpole changes into adult, their apparatus and digestive

tract become meat-eating structures • Intestines become much shorter

• Adult amphibians are almost completely carnivorous• Legless amphibians can only snap jaws open and shut to

catch prey • Some have long sticky tongues to capture insects

• Ex. Salamanders and frogs• Food moves from the mouth to the esophagus and then into

the stomach. Food from the stomach moves into the small intestine, then the large intestine, and then the cloaca• Cloaca- muscular cavity where digestive wastes, urine,

and eggs/sperm leave body

RespirationGas exchange occurs through the skin, lining

of mouth cavity, and lungs (*varies depending on the Amphibian)

Lungs replace gills when amphibian becomes adult

Some have well-developed lungsEx. Frogs, toads

Some have not as well-developed lungs or no lungs at all Ex. Salamanders (*most terrestrial salamanders

have no lungs)Lungless salamanders exchange gas through skin

and lining of mouth cavity

CirculationDouble loop circulation

First loop: carries oxygen-poor blood from heart to the lungs and skin, and then carries oxygen-rich blood from the lungs and skin back to the heart

Second loop: transports oxygen-rich blood from the heart to rest of body, and then oxygen-poor blood from body back to heart

Amphibian heart has three chambers Right atrium- where oxygen-poor blood from body

entersLeft atrium- where oxygen-rich blood from the

lungs and skin enters Ventricle- where blood is emptied when right and

left atrium contracts, where blood is pumped into vessels

Excretion

Amphibians have kidneysKidneys filter waste from blood Kidney excretes urine

The urine travels through ureters (tubes) into the cloaca

Urine could be stored temporarily in small urinary bladder or passed outside

ReproductionAmphibians eggs don’t have a shell so there

eggs get dried out without moistureMost amphibians have external fertilization

and some like most salamanders have internal

Frog reproduction The male frog climbs on the back of the

female frog and squeezes and the female frog releases about 200 eggs then the male fertilizes the eggs

The eggs are encased in a sticky, transparent jelly that attaches to underwater plants and is difficult for underwater predators to grasp them

The yolk nourishes the embryo until they hatch into tadpoles

Movement Amphibian larvae are much like fish, by

wiggling their body and using a flatten tail for propulsion

Most adults, like other four limb vertebrates, use their front and back legs

some have suction cups (disk on their toes) that are used for climbing

ResponseSame basic parts of a fishHave well develop nervous and sensory systemsEyes are large and can move aroundNictitating membrane- transparent membrane

that protects the eye from damage underwater and keeps it moist on land

Can spot and respond to moving insects Has eardrums called tympanic membranes that

vibrates in respond to sound, allowing hearing

Digestion and Excretion

movement

nervous

Life Cycle

There are 3 groups of amphibians in the presentSalamandersFrogs & ToadsCaecilians

The 3 groups of amphibiansSalamanders are members of the order Urodela and have

long bodies and tails. They are carnivorous. The living space where they make their homes varies from moist woods or water.

Frogs & Toads are members of the order Anura and share the famous ability to jump. Frogs usually have long legs and make lengthy jumps while Toads have short legs and make shorter hops. Frogs usually stay close to water while Toads can live from the moist woods to even deserts. After most of their infant lives they lose their tales in their adult stages.

Caecilians are members of the Apoda. They are legless animals that live in water or dig into damp soil or sediment. They are carnivorous feeding on small invertebrates. Some Caecilians have fishlike scales embedded into their skin showing that some amphibians don’t fit the main description that you’d think of.

EcologyAmphibians have to live close to water but a

few have adapted well enough to make use of the small amount of water in the desert.

They are usually hunted by birds or mammals but have adaptations that help them camouflage or secrete toxins.

Their numbers are decreasing at the moment and scientist have yet to figure out why.

Ch.30-3 Review

Which one of these statements about Amphibians is not true?A. They are cold blooded

B. Has moist skin that contains mucus glands

C. lacks scales and claws

D. lives in water as a adult and on land as a larvae

What would have been a challenge that amphibians had to face from the transition from water to land?A. Breath air

B. Protect themselves and their eggs from drying out

C. Couldn’t see

D. Both A & B

A frogs brain has the same basic parts of a fish, but a frog can sense and respond to movement more efficiently.

TRUE

FALSE

Which order would this amphibian be classified as?

Caecilian

Which group of amphibians can fertilize internally?A. Salamanders

B. Toads and Frogs

C. Caecilians

D. Snakes