Amphibians and Reptiles
Ron ChakrabartyMark Juhn
Daniel MontgomeryAndrew Tung
AmphibiansFamily Amphibia
Amphibians – General/Unique CharacteristicsMoist, glandular skin with no scales
Feet lack claws and are often webbed
Possession of gills at some point in its lifeLack of amnion in the egg
Embryonic membrane and surrounds and protects the embryo
Amphibians - EvolutionFirst vertebrates to begin exploring
terrestrial landEarliest fossil found about 400 million years Most likely evolved from fishAir bladder mutated/adapted to lungsFins evolved into limbs?
To give stronger support
Amphibians – Classification into Orders There are three different orders for an
amphibian Anura – 4200 species of frogs and toads Urodela – 430 species of newts and
salamanders Gymniophiona – 165 known species of
caecilians
Amphibians - AnuraConsists of frogs and toadsHave tails as tadpoles, but lack tails as adultsLong hind legs for jumping and swimmingLive mostly in freshwater, but some live in drier
habitatsCommon Anurans – bullfrog, spring peeper, American
toad, spade-foot toadThe difference between a frog and a toad is that toads
have shorter legs, drier skin, and more warts than frogs.
Length – 1 to 12 inchesEat mainly insects and small invertebrates
Amphibians – Urodeles – also called CaudataConsist of newts and salamandersHave long tails and small, underdeveloped
feet.Includes the largest amphibian in the world –
the Giant Salamander lives in Japan and can be up to 5 feet long.
Live near water or in moist soilEat insects and some smaller invertebratesIncludes one genus that is shaped like an eel
– no legs or pelvis and has gills and lungs
Amphibians - GymniophionaConsists of caecilians
Small, worm-shaped amphibiansBlindLegless
Only 165 species known because some are so small
Largest caecilian is 4.5 feet long
Amphibians - SymmetryAmphibians have bilateral symmetry
They can be divided into identical halves across exactly one plane
CephalizedConcentration of brain cells near the anterior
end of the amphibian
Amphibians – Body cavityAll amphibians are coelomates
All have a true coelom A coelom is a hollow, fluid-filled body cavity that is
lined both internally and externally by mesoderm. Provides support for the chest
Amphibians – Structural SupportSkeleton - General
Vertebrae – form a backboneLimbs – support while walking or standing
Pectoral girdle – shoulder and supporting bones from front limbs
Pelvic girdle – “hips” from back limbsCervical vertebra – neck movement
Amphibians – SkeletonFrogs – specialized bones in skeleton,
different from other amphibiansRadio-ulna – “forearm”Tibiofibula – “calf”Phalanges – fingers adapted for jumping – on
all four limbsBones are generally thicker (for impact when
landing)
Amphibians – SkinServes as method of respiration and as a
method of protectionMakes them more affected by pollution –
chemicals can diffuse into the bodyHealth of amphibians in one habitat represents
the condition of their environment
Amphibians - RespirationLarvae have gills
Allow oxygen into the organism when it is underwater
Larvae undergoes metamorphosis Gills disappear and lungs are made
Amphibians - RespirationAdult amphibians can breathe through their
skin and lungs.Pulmonary respiration (breathing through
lungs) – takes in air through nostrils and mouth Adult frogs have to voluntarily force air down
their throats (buccal pumping) because they lack a diaphragm, and this is why they mainly use cutaneous respiration.
Amphibians - RespirationCutaneous respiration (breathing through skin) –
many amphibians use this type of respiration as their main type of breathing and use their lungs as backupSkin is moist and permeable
Allows diffusion of oxygen, water, and carbon dioxideHowever, this makes amphibians vulnerable to
dehydration
Amphibians – Transportation and CirculationAmphibians have a three-chambered heartCirculatory system has two loops
Pulmonary circulation Carries deoxygenated blood to lungs from heart
Moves through contraction of atriumSystemic circulation
Oxygenated blood from heart to rest of body
Amphibians – Transportation and CirculationBlood in heart
Deoxygenated blood enters right atriumPulmonary veins carry oxygenated blood from
lungs to left atriumOxygenated and deoxygenated blood mix in
ventricleVentricle pumps blood to lungs
All known as the “double-loop” system
Amphibians – Digestive SystemAll adults are carnivorous
Many larva are herbivorous Frogs
Other larva are carnivorous Salamander
Amphibians - Digestive SystemPharynx – opens into the esophagusEsophagus – elastic tube that brings food down from
the pharynx to the stomachAllows amphibian to swallow large amounts of food
Stomach – has tiny glands that secrete gastric juicesDigests/breaks down food
Small intestine – Digestion is completedDuodenum – upper portionIleum – coiled middle portion of small intestine
Mesentery – holds small intestine in place
Large Intestine – Holds waste
Amphibians – ExcretionSmall intestine empties into the large
intestineIndigestible waste is collected
Processed by kidneysPushed into cloaca
Waste from kidneys, urinary bladder, eggs and sperm pass through cloaca
Waste exits through vent
Amphibians – Water BalanceAmphibians skin is permeable
Water and nutrients can come in through the skin
However, this also makes it more vulnerable to dehydration because water can diffuse out of their skin in dry environments Therefore, amphibians must live in wet
environments Many are active only at night when water loss is
minimized
Amphibians – Water BalanceUrine
Flows from kidneys to cloaca through urinary ductsGoes to urinary bladder
Water-storing organ
Amphibian larva excrete nitrogen compounds as ammoniaVery toxic, so must be excreted quickly or diluted
with waterTo conserve water, adults instead transform
ammonia into urea Less toxic Excreted with less water although uses energy
Amphibians – ReproductionFrogs come out of hibernation in the first
days of springMigrate to ponds and streams, where males
attract females by using vocal sacs Females only respond to frogs of the same species
When females come, males climb onto their backs and “hug” them – called amplexus – until eggs are laid through the vent .Into the water for most amphibiansWhen eggs are laid, males discharge sperm
onto the eggs – direct external fertilization
Amphibians – Reproductive SystemMales
Sperm cells develop in the testesGoes to urinary tract during mating season
FemaleEggs develop in the ovariesEggs enlarge, mature, and move to the body
cavity during breeding season Leave female through oviducts and are coated with
a protective slime
Amphibians - DevelopmentTadpoles hatch within a few days and develop
gillsEventually, a mouth opensGoes through metamorphosis – Changes from an
aquatic larva to an adult Legs Lungs Teeth Tail disappears
Metamorphosis happens because of thyroxine Produced in thyroid, circulates through blood,
stimulates metamorphosis
Amphibians – DevelopmentAlternative reproductive patterns
Some amphibians lay eggs in a warmer environment Under a rock, in a log, in a tree Some frogs build a nest
Made out of mucus, whipped into a frothy material by kicking it rapidly
Some do not go through metamorphosis Salamanders that remain in the larval stage for
their whole life No thyroxine produced
Some do not go through the larval stage Hatch from eggs as small version of adult
Amphibians – Nervous SystemTympanic Membrane – eardrumColumella – bone that transmits sounds from
the eardrum to the inner earOlfactory Lobes – sense of smellOptic Lobes - sight
Amphibians – Nervous SystemBrain
Same size as fishCerebrum – responsible for learningCerebellum – muscle coordination
Nerves extend directly from brain to body, protected by spinal cord
Lateral line – detect vibrations in waterLost during metamorphosis
ReptilesFamily Reptilia
Evolved from amphibians Oldest known reptiles date back to early
carboniferous period (359- 299 m.y.a)Small, four-leggedAte insectsLived in dry climates
History
Evolved from thecodonts. Success
Legs placed under bodyAdapted to dry climatesMass extinction
Dinosaurs
ExtinctionAsteroid Impact Hypothesis
Huge asteroid hit Yucatán PeninsulaDust cloudSupported by high amount of iridium in
sedimentsMultiple Impact Hypothesis
Bad environmental conditionsMany asteroid impacts
Dinosaurs
Reptiles – Structural Support/ Body Cavity/SymmetrySymmetry- Bilateral Body Cavity- ColoemStructural Support- Endoskeleton
Have breast bone to guard lungs and heart
Reptiles - RespirationHave large lungs for gas exchangeLunges divided into chambersAlveoli- small sacs that are created by the
folding of the lungs. (more oxygen)Snakes
Only right lung functions, as big as half the length of body
Left is nonfunctional or gone
Reptiles - RespirationLungs are filled by expanding rib cageRibs contract to normal and air is released
from lungsSimilar to human respiration
Reptiles - Water Balance/ExcretionRespiratory and excretion systems help
reptiles conserve waterAll tissues for respiration are internal to keep
moistureLand reptiles give of nitrogenous waste in the
form of uric acidReptiles lose little water in urine
Reptiles – Water Balance/ExcretionRespiratory and excretion systems help
reptiles conserve waterAll tissues for respiration are internal to keep
moistureLand reptiles give of nitrogenous waste in the
form of uric acidReptiles lose little a water in urine
Reptiles - ClassificationClassified into four orders
Chelonia – Turtles and tortoisesCrocodilia – Alligators and crocodilesSquamata – Lizards and snakesRhynchocephalia - tuataras
Reptiles - Chelonia 250 species of turtles and tortoisesTortoise- TerrestrialTurtle- AquaticAncient chelonians- like modern turtles and tortoises Turtle design
Body enveloped in a shell Carapace- Dorsal of the shellPlastrons- Underside of shellRibs attached to inner carapacePelvic and pectoral girdles- inside ribs Sharp beak
Tortoise designDomed carapace
defense from predators limbs covered in thick scales
Order Chelonia
Chelonia mydas(green sea turtle)
Reptiles - CheloniaHabitats
Some always terrestrial or aquatic, some live in both Shells and limbs- adapted to different habitats
Aquatic turtles- streamlined, disk-shaped shell for turning and webbed feet
Limbs are flippers for swimming
ReproductionOffspring born through eggsFemale finds a location, makes a hole, puts eggs in
it, covers nestLeaves young alone to hatch
CrocodilesClosest related to dinosaurs Heavy-bodied and aquaticHave a valve at the back of the throat
Prevents water from entering the air passage
Crocodilia
Crocodylus rhombifer(Cuban Crocodile)
Reptiles - SquamataLizards
Eat insectsSome plants
Predator Protection Agility, speed, and camouflage Autotomy
Reptiles - SquamataSnakes
No legs Ancestors lived in thick vegetation, legs slowed
themBackbone of 100 to 400 vertebrae
Ribs attached Framework for muscles
Muscles affect skin, scales enlarge and contract which moves snake
Kill by constriction or injecting venom
Notechis scutatus(Tiger Snake)
(Elapid)
Bitis gabonica(Gaboon Viper Snake)
Dispholidus typus(Boomslang Snake)
(grooved teeth in the back of the mouth)
Boa constrictor
Reptiles - RhynchocephaliaAncient, only Tuataras from genus
SphenodonTuatara means spiny crestLive only on New ZealandBurrow during the day and eat small insects,
worms, and animals during the night.
Sphenodon Punctatus(Tuataras)
Reptiles – Transportation and CirculationTwo circulatory loops
Pulmonary loop Carries deoxygenated blood from the heart to the
lungsSystematic loop
Carries oxygenated blood from the heart to the tissues
Carries deoxygenated blood back to the heart
Two atria, two ventricles or one divided by the septum
Reptiles – Transportation and CirculationHigh flexibility in a reptilian heartPulmonary arteries can restrict
Skips lungs. Deoxygenated bloodbodySome take blood from lungs for energy
conservationReptiles stop breathing when inactive
When active, blood goes to lungs, and more oxygen goes to the muscles
Reptiles – Nutrition and DigestionMouth, tongue, teeth, esophagus, stomach,
and rectum Simple digestive tract
Moderately sized gut Don’t chew food like mammalsSome herbivorous reptiles swallow rocks
called gastrolithes to help digestionReptiles- Most acidic digestion system of any
animal
Reptiles – Water Balance/ExcretionTwo kidneysReptiles use the colon to reabsorb waterLand reptiles remove nitrogenous waste in
uric acidLittle water lost
Some reptiles can get rid of salt with salt glands and nasal areas
Reptiles – Nervous SystemBrain size= an amphibian
Cerebrum is largerGood vision
Large optic lobesHearing
Sound waves hit tympanic membrane (eardrum)
Columella moves and takes sound to the inner ear
Recognized in inner ear by receptors
Jacobson’s organOn roof of mouthSenses odorsPit vipers
Detect warm-blooded prey body heat Heat-sensitive pit under eyes
Detects position of the prey
Nervous System Cont.
Reptiles – Reproductive SystemThree patterns
OviparityOvoviviparityViviparity
Differ in length of time eggs are in the female and the nutrition given
Reptiles – Reproductive SystemOviparity
Female reproductive tract puts shell on egg Egg placed in an optimal place
Ovoviparity Eggs stay in female body Right before hatching-eggs are laid
Or hatch in the female
Reptiles – Reproductive SystemViviparity
No shellStays in female body until bornPlacenta give nutrients and oxygen
motherembryo Placenta formed from egg membranes
Reptiles – Reproductive SystemMany mothers don’t care for eggs or
offspringSome lizards and snakes protect and keep eggs
warm until hatchingMost care- Crocodiles and alligators
Female crocodile builds a nestCarries offspring in mouth to water
The End(Works Cited on next page)
Amphibians and ReptilesWorks Cited
"Amphibian." msn encarta. 2008. Microsoft. 24 Mar 2009 <http://encarta.msn.com/encyclopedia_761574532/Amphibian_(animal).html#s11>.
"Frog Blog - Amphibian Respiration." houstonzooblog.com. 10 Mar 2008. Houston Zoo Blog. 23 Mar 2009 <http://www.houstonzooblog.com/frog_blog/2008/03/amphibian-respi.html>.
http://www.mcwdn.org/Animals/Reptile.html Lerner, Lee. "Amphibians." The Gale Encyclopedia of Science 2008: 189-191.
Gale Virtual Reference Library. Gale. Vernon Hills High School. 23 Mar 2009 <http://go.galegroup.com/>.
Nagel, Rob. "Amphibians." UXL Encyclopedia of Science 2002: 134-137. Gale Virtual Reference Library. Gale. Vernon HillsHigh School. 23 Mar 2009 <http://go.galegroup.com>.
Postlethwait, John, and Janet Hopson. Modern Biology. Austin: Harcourt Education, 2008.
W. Ben Cash, Richard G. Zweifel, T. R. Smithson, "Amphibia", in AccessScience@McGraw-Hill, http://www.accessscience.com, DOI 10.1036/1097-8542.029600
Top Related