Amphibians and Reptiles - Vernon Hills High School

Ron Chakrabarty
Mark Juhn
Daniel Montgomery
Andrew Tung
Family Amphibia
Amphibians – General/Unique
 Moist, glandular skin with no scales
 Feet lack claws and are often webbed
 Possession of gills at some point in its life
 Lack of amnion in the egg
 Embryonic membrane and surrounds and protects the
Amphibians - Evolution
 First vertebrates to begin exploring terrestrial land
 Earliest fossil found about 400 million years
 Most likely evolved from fish
 Air bladder mutated/adapted to lungs
 Fins evolved into limbs?
To give stronger support
Amphibians – Classification into
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 - Anura
 Consists of frogs and toads
 Have tails as tadpoles, but lack tails as adults
 Long hind legs for jumping and swimming
 Live mostly in freshwater, but some live in drier habitats
 Common Anurans – bullfrog, spring peeper, American
toad, spade-foot toad
 The difference between a frog and a toad is that toads have
shorter legs, drier skin, and more warts than frogs.
 Length – 1 to 12 inches
 Eat mainly insects and small invertebrates
Amphibians – Urodeles – also
called Caudata
 Consist of newts and salamanders
 Have 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
 Live near water or in moist soil
 Eat insects and some smaller invertebrates
 Includes one genus that is shaped like an eel – no legs
or pelvis and has gills and lungs
Amphibians - Gymniophiona
 Consists of caecilians
 Small, worm-shaped amphibians
 Blind
 Legless
 Only 165 species known because some are so small
 Largest caecilian is 4.5 feet long
Amphibians - Symmetry
 Amphibians have bilateral symmetry
 They can be divided into identical halves across exactly
one plane
 Cephalized
 Concentration of brain cells near the anterior end of the
Amphibians – Body cavity
 All 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 Support
 Skeleton - General
 Vertebrae – form a backbone
 Limbs – support while walking or standing
Pectoral girdle – shoulder and supporting bones from front
Pelvic girdle – “hips” from back limbs
 Cervical vertebra – neck movement
Amphibians – Skeleton
 Frogs – specialized bones in skeleton, different from
other amphibians
 Radio-ulna – “forearm”
 Tibiofibula – “calf”
 Phalanges – fingers adapted for jumping – on all four
 Bones are generally thicker (for impact when landing)
Amphibians – Skin
 Serves as method of respiration and as a method of
 Makes them more affected by pollution – chemicals
can diffuse into the body
 Health of amphibians in one habitat represents the
condition of their environment
Amphibians - Respiration
 Larvae have gills
 Allow oxygen into the organism when it is underwater
 Larvae undergoes metamorphosis
 Gills disappear and lungs are made
Amphibians - Respiration
 Adult amphibians can breathe through their skin and
 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
Amphibians - Respiration
 Cutaneous respiration (breathing through skin) – many
amphibians use this type of respiration as their main type
of breathing and use their lungs as backup
 Skin is moist and permeable
 Allows diffusion of oxygen, water, and carbon dioxide
 However, this makes amphibians vulnerable to dehydration
Amphibians – Transportation and
 Amphibians have a three-chambered heart
 Circulatory system has two loops
 Pulmonary circulation
Carries deoxygenated blood to lungs from heart
 Moves through contraction of atrium
 Systemic circulation
Oxygenated blood from heart to rest of body
Amphibians – Transportation and
 Blood in heart
 Deoxygenated blood enters right atrium
 Pulmonary veins carry oxygenated blood from lungs to
left atrium
 Oxygenated and deoxygenated blood mix in ventricle
 Ventricle pumps blood to lungs
All known as the “double-loop” system
Amphibians – Digestive System
 All adults are carnivorous
 Many larva are herbivorous
 Other larva are carnivorous
Amphibians - Digestive System
 Pharynx – opens into the esophagus
 Esophagus – elastic tube that brings food down from the
pharynx to the stomach
 Allows amphibian to swallow large amounts of food
 Stomach – has tiny glands that secrete gastric juices
 Digests/breaks down food
 Small intestine – Digestion is completed
 Duodenum – upper portion
 Ileum – coiled middle portion of small intestine
Mesentery – holds small intestine in place
 Large Intestine – Holds waste
Amphibians – Excretion
 Small intestine empties into the large intestine
 Indigestible waste is collected
 Processed by kidneys
 Pushed into cloaca
 Waste from kidneys, urinary bladder, eggs and sperm
pass through cloaca
 Waste exits through vent
Amphibians – Water Balance
 Amphibians 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 Balance
 Urine
 Flows from kidneys to cloaca through urinary ducts
 Goes to urinary bladder
Water-storing organ
 Amphibian larva excrete nitrogen compounds as ammonia
 Very toxic, so must be excreted quickly or diluted with water
 To conserve water, adults instead transform ammonia into
Less toxic
Excreted with less water although uses energy
Amphibians – Reproduction
 Frogs come out of hibernation in the first days of
 Migrate 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 amphibians
 When eggs are laid, males discharge sperm onto the
eggs – direct external fertilization
Amphibians – Reproductive System
 Males
 Sperm cells develop in the testes
 Goes to urinary tract during mating season
 Female
 Eggs develop in the ovaries
 Eggs enlarge, mature, and move to the body cavity
during breeding season
Leave female through oviducts and are coated with a
protective slime
Amphibians - Development
 Tadpoles hatch within a few days and develop gills
 Eventually, a mouth opens
 Goes through metamorphosis – Changes from an
aquatic larva to an adult
Tail disappears
 Metamorphosis happens because of thyroxine
 Produced in thyroid, circulates through blood, stimulates
Amphibians – Development
 Alternative 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 System
 Tympanic Membrane – eardrum
 Columella – bone that transmits sounds from the
eardrum to the inner ear
 Olfactory Lobes – sense of smell
 Optic Lobes - sight
Amphibians – Nervous System
 Brain
 Same size as fish
 Cerebrum – responsible for learning
 Cerebellum – muscle coordination
 Nerves extend directly from brain to body, protected
by spinal cord
 Lateral line – detect vibrations in water
 Lost during metamorphosis
Family Reptilia
 Evolved from amphibians
 Oldest known reptiles date back to early carboniferous
period (359- 299 m.y.a)
 Small, four-legged
 Ate insects
 Lived in dry climates
 Evolved from thecodonts.
 Success
 Legs placed under body
 Adapted to dry climates
 Mass extinction
 Extinction
 Asteroid Impact Hypothesis
 Huge asteroid hit Yucatán Peninsula
 Dust cloud
 Supported by high amount of iridium in sediments
 Multiple Impact Hypothesis
 Bad environmental conditions
 Many asteroid impacts
Reptiles – Structural Support/ Body
 Symmetry- Bilateral
 Body Cavity- Coloem
 Structural Support- Endoskeleton
 Have breast bone to guard lungs and heart
Reptiles - Respiration
 Have large lungs for gas exchange
 Lunges divided into chambers
 Alveoli- 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
 Left is nonfunctional or gone
Reptiles - Respiration
 Lungs are filled by expanding rib cage
 Ribs contract to normal and air is released from lungs
 Similar to human respiration
Reptiles - Water Balance/Excretion
 Respiratory and excretion systems help reptiles
conserve water
 All tissues for respiration are internal to keep moisture
 Land reptiles give of nitrogenous waste in the form of
uric acid
 Reptiles lose little water in urine
Reptiles – Water Balance/Excretion
 Respiratory and excretion systems help reptiles
conserve water
 All tissues for respiration are internal to keep moisture
 Land reptiles give of nitrogenous waste in the form of
uric acid
 Reptiles lose little a water in urine
Reptiles - Classification
 Classified into four orders
 Chelonia – Turtles and tortoises
 Crocodilia – Alligators and crocodiles
 Squamata – Lizards and snakes
 Rhynchocephalia - tuataras
Reptiles - Chelonia
250 species of turtles and tortoises
Tortoise- Terrestrial
Turtle- Aquatic
Ancient chelonians- like modern turtles and tortoises
Turtle design
 Body enveloped in a shell
 Carapace- Dorsal of the shell
 Plastrons- Underside of shell
 Ribs attached to inner carapace
 Pelvic and pectoral girdles- inside ribs
 Sharp beak
Order Chelonia
 Tortoise design
 Domed carapace
defense from predators
limbs covered in thick scales
Chelonia mydas
(green sea turtle)
Reptiles - Chelonia
 Habitats
 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
 Reproduction
 Offspring born through eggs
 Female finds a location, makes a hole, puts eggs in it,
covers nest
 Leaves young alone to hatch
 Crocodiles
 Closest related to dinosaurs
 Heavy-bodied and aquatic
(Cuban Crocodile)
 Have a valve at the back of the throat
 Prevents water from entering the air passage
Reptiles - Squamata
 Lizards
 Eat insects
 Some plants
 Predator Protection
 Agility, speed, and camouflage
 Autotomy
Reptiles - Squamata
 Snakes
 No legs
Ancestors lived in thick vegetation, legs slowed them
 Backbone of 100 to 400 vertebrae
Ribs attached
 Framework for muscles
 Muscles affect skin, scales enlarge and contract which moves
 Kill by constriction or injecting venom
Notechis scutatus
(Tiger Snake)
Dispholidus typus
(Boomslang Snake)
(grooved teeth in the
back of the mouth)
Bitis gabonica
(Gaboon Viper Snake)
Boa constrictor
Reptiles - Rhynchocephalia
 Ancient, only Tuataras from genus Sphenodon
 Tuatara means spiny crest
 Live only on New Zealand
 Burrow during the day and eat small insects, worms,
and animals during the night.
Sphenodon Punctatus
Reptiles – Transportation and
 Two circulatory loops
 Pulmonary loop
Carries deoxygenated blood from the heart to the lungs
 Systematic 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
 High flexibility in a reptilian heart
 Pulmonary arteries can restrict
 Skips lungs. Deoxygenated bloodbody
 Some take blood from lungs for energy conservation
 Reptiles stop breathing when inactive
 When active, blood goes to lungs, and more oxygen
goes to the muscles
Reptiles – Nutrition and Digestion
 Mouth, tongue, teeth, esophagus, stomach, and
 Simple digestive tract
 Moderately sized gut
 Don’t chew food like mammals
 Some herbivorous reptiles swallow rocks called
gastrolithes to help digestion
 Reptiles- Most acidic digestion system of any animal
Reptiles – Water Balance/Excretion
 Two kidneys
 Reptiles use the colon to reabsorb water
 Land reptiles remove nitrogenous waste in uric acid
 Little water lost
 Some reptiles can get rid of salt with salt glands and
nasal areas
Reptiles – Nervous System
 Brain size= an amphibian
 Cerebrum is larger
 Good vision
 Large optic lobes
 Hearing
 Sound waves hit tympanic membrane (eardrum)
 Columella moves and takes sound to the inner ear
 Recognized in inner ear by receptors
Nervous System Cont.
 Jacobson’s organ
 On roof of mouth
 Senses odors
 Pit vipers
Detect warm-blooded prey body heat
Heat-sensitive pit under eyes
 Detects position of the prey
Reptiles – Reproductive System
 Three patterns
 Oviparity
 Ovoviviparity
 Viviparity
 Differ in length of time eggs are in the female and the
nutrition given
Reptiles – Reproductive System
 Oviparity
 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 System
 Viviparity
 No shell
 Stays in female body until born
 Placenta give nutrients and oxygen motherembryo
Placenta formed from egg membranes
Reptiles – Reproductive System
 Many mothers don’t care for eggs or offspring
 Some lizards and snakes protect and keep eggs warm
until hatching
 Most care- Crocodiles and alligators
 Female crocodile builds a nest
 Carries offspring in mouth to water
The End
(Works Cited on
next page)
Amphibians and Reptiles
Works Cited
 "Amphibian." msn encarta. 2008. Microsoft. 24 Mar 2009
 "Frog Blog - Amphibian Respiration." 10 Mar 2008. Houston Zoo
Blog. 23 Mar 2009 <>.
 Lerner, Lee. "Amphibians." The Gale Encyclopedia of Science 2008: 189-191. Gale Virtual
Reference Library. Gale. Vernon Hills High School. 23 Mar 2009
 Nagel, Rob. "Amphibians." UXL Encyclopedia of Science 2002: 134-137. Gale Virtual
Reference Library. Gale. Vernon HillsHigh School. 23 Mar 2009
 Postlethwait, John, and Janet Hopson. Modern Biology. Austin: Harcourt Education,
 W. Ben Cash, Richard G. Zweifel, T. R. Smithson, "Amphibia", in
[email protected],, DOI 10.1036/10978542.029600

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