Section 30-3Amphibia

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Section 30-3 Learning TargetsWhat is an amphibian?Explain are amphibians

adapted for life on land?Name the main groups of

living amphibians?

What is an AmphibianAmphibian means “double life”

which emphasizes that animals live both in water and land!

Amphibians are:• Vertebrates (some exceptions)• Lives in water as larva and land as

an adult• Moist skin that contains mucous

glands• Lacks scales and claws

Form and Function in Amphibians•Feeding

–Dual life exhibited•Tadpoles typically herbivores•Adult frogs are completely carnivores

– Eat almost anything that they can catch and swallow

– At the end of the large intestine is a muscular cavity called the cloaca through which digestive wastes, urine, and eggs or sperm leave the body.

Respiration

– In most larval amphibians gas exchange occurs through the skin and gills

– Adult Amphibians respire through the skin and lining of mouth cavity•Most adults have well developed

lungs•Many terrestrial salamanders do

not have lungs at all!

Circulation• Have a closed circulatory system• Forms a double loop system

– First Loop• Takes oxygen poor blood from the heart to

the lungs and skin (to get oxygenated!)• Then takes oxygen rich blood from the

lungs and the skin back to the heart ( to be distributed to body)

– Second Loop• Takes oxygen rich blood from the heart to

the rest of the body• Then takes oxygen poor blood back to the

heart.

Excretion•Amphibians have kidneys to filter wastes from the blood–Urine produced by kidneys is passed down the ureters to the cloaca to be released

Reproduction• Most species use external

fertilization– Eggs do not have shells and

would dry out easily– Most females lay eggs in the

water and males externally fertilize them in the water

– Yolk of the egg nourishes young until they hatch into tadpoles

• Few species like salamanders use internal fertilization.

Movement•Larva often move much

like fish•Adults use their front and

back legs to move in a variety of ways– Frogs and toads have well

developed back legs which enable them to jump long distances

Response• Brains consist of the same basic

parts as a fish• Amphibians have well developed

nervous and sensory systems.• Sight

– Have nictitating membrane to protect eyes in water

– Great eye sight to sense movement– Cannot see in color as well as fish

• Hearing– Amphibians hear through tympanic

membranes or eardrums located on either side of their head.

Groups of Amphibia

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Groups of Amphibians

•Modern amphibians can be classified into three groups–Salamanders–Frogs and Toads–Caecilians

Salamanders• Order : Urodela• Containing: Salamanders and

Newts• Most have:

– Long Bodies– Tails– Four Legs

• Adults and larva are carnivores• Adults usually live in moist woods• Some salamanders (such as

mudpuppies) retain their gills and live in water their whole lives.

Frogs and Toads• Order: Anura• Contains: Frogs and Toads• Frogs

– Usually have long legs = long jumps– More closely tied to water than toads

• Toads– Have relatively short legs = short

hops– Usually found in moist woods and

some even in desserts

• Adult frogs and toads lack tails

Caecilians (seh-SILL-yens) • Order: Apoda• Consist of small invertebrates that live in

water or burrow into moist soil• Feed on small invertebrates such as

termites• Many have fishlike scales imbedded in

their skin• Virtually Blind and deaf• Have sensory tentacles for sensory

information• Some have toxic glands in their skin

which protect them from being eaten.• Have dozens of needle sharp teeth for

eating their prey.

• Many amphibians make and ideal meal for predators

• Most have adaptations to protect them from their predators such as– Colors – Markings– Toxins/poisonous– Unpleasant taste

Ecology of Amphibians

Frog Dissection

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