REPTILES

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REPTILES AMPHIBIANS

• The Rise of Amphibians (Devonian Period)
• A. Amphibians have a body plan and mode
  reproduction somewhere between
• fishes and reptiles.
• They are vertebrates with a bony
• endoskeleton and a four-legged aquatic
• ancestor.

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REPTILES AMPHIBIANS

• The 4 classes of terrestrial (tetrapods)
  vertebrates
• Amphibians
• Reptiles
• Birds
• Mammals

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REPTILES AMPHIBIANS

• Scientific classification
• Kingdom AnimaliaPhylum ChordataSubphylum
  VertebrataClass Amphibia

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REPTILES AMPHIBIANS

• Subclasses and Orders of Amphibians
• Order Temnospondyli- extinctSubclass
  Lepospondyli- extinctSubclass Lissamphibia Order
  s
•  Anura  Caudata  Gymnophiona

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REPTILES AMPHIBIANS

• 1. Life on land presented new challenges
  to the emerging amphibians.
• The idea here is that asteroids that hit
• earth caused the mass extinction of
• marine life and affected much of the
• available O2 at the seas surface. Since
• the tetrapods had lungs they could take
• advantage of gulping air while spending
• some of their time on land.

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REPTILES AMPHIBIANS

• Scientists say no significant genetic
• change would be required to make the
• transaction from lobed fins to limbs.
• They contend that even a single
• mutation in one of the so-called,
• master genes could lead to a big
• change in morphology.

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REPTILES AMPHIBIANS

• a. Water availability was not reliable.
• b. Air temperatures were variable, and air
  itself was not the strong supporting
  medium that water was, but it was a richer
  source of oxygen. Lungs had to be modified
  in ways that enhanced O2 uptake. Circulatory
  systems became more efficient in rapidly
• moving oxygen to cells.

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REPTILES AMPHIBIANS

• Both of these modifications increase
• the capacity for aerobic respiration,
• thus generating more ATP for use in
• increased activity.
• c. New habitats, including vast arrays of
• plants, insects, necessitated keener
• sensory (vision, hearing, balance) input.
• As a result, different regions of the brain
• further developed.

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REPTILES AMPHIBIANS

• d. Fortunately, climate shifts in the
• Carboniferous provided an abundance
• of insects as food for the amphibians.

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REPTILES AMPHIBIANS

• Amphibians developed with the characteristics of
  pharyngeal slits/gills, a dorsal nerve cord, a
  notochord, and a post-anal tail at different
  stages of their life. Though early tetrapods
  (which appeared 390 million years ago in the
  Devonian period) are often referred to as
  "amphibians", the first true amphibians appeared
  during the early Carboniferous period.

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REPTILES AMPHIBIANS

• Superorder Salientia
• Triadobatrachus (Triassic)
• Order Anura (frogs and toads) Jurassic to recent
  - 5,296 recent species
• Order Caudata or Urodela (salamanders) Jurassic
  to recent - 555 recent species
• Order Apoda (caecilians) Jurassic to recent -
  171 recent species

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REPTILES AMPHIBIANS

• 2. Existing amphibians share several
• common characteristics
• a. All have bony endoskeletons and
• usually four legs.
• b. Most shed their eggs into water,
• which is also home to a free-
• swimming larval stage.

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REPTILES AMPHIBIANS

• c. Depending on their habitat,
• amphibians can respire by use of
• gills, lungs, skin, and pharyngeal
• lining.
• d. The skin is usually thin and some-
• times supplied with glands that
• produce toxins. Well see this
• shortly.

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REPTILES AMPHIBIANS

• The word amphibian comes from the Greek
  meaning, both (amphi), and bios, meaning,
  life.
• It describes cold-blooded animals with backbones
  that spend their lives both in fresh water and on
  land.

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REPTILES AMPHIBIANS

• When we say, cold-blooded we mean that the
  amphibians do not hold or regulate their own body
  temperature.
• Their internal body temperature depends on the
  external environment. They must absorb the warmth
  of the sun or become sluggish at very cold
  temperature to maintain bodily heat.

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REPTILES AMPHIBIANS

• The Class Amphibia contains three orders
• Anura (frogs and toads)
• Urodela (salamanders and newts)
• Apoda (caecilians)

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REPTILES AMPHIBIANS

• FROG TOAD SALAMANDER

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REPTILES AMPHIBIANS

• NEWTS CAECILIANS

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REPTILES AMPHIBIANS

• Most amphibians share 5 key characteristics
• 1. Legs adapted to living on land (frogs,
  toads, salamanders, newts all have 4 legs)
• 2. Lungs larval amphibians have gills, most
• adult amphibians breathe with a pair
  of lungs (salamanders are an
  exception)

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REPTILES AMPHIBIANS

• 3. Double-loop circulation two large veins
  called Pulmonary veins return oxygen-rich
  blood from the lungs to the heart. Oxygen-rich
  blood is then pumped to the tissues.
• 4. Partially divided heart the atrium of the
  heart is divided into left and right sides, but
  the ventricle is not. A mixture of oxygen- rich
  and oxygen-poor blood is delivered to the
  tissues.

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REPTILES AMPHIBIANS

• 5. Cutaneous respiration - besides
  breathing with their lungs, amphibians
  take up oxygen through their skin.

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REPTILES AMPHIBIANS

• Double-loop circulation in amphibians

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REPTILES AMPHIBIANS

• Life Cycle Metamorphosis of a Frog (pg.
  758-759)

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REPTILES AMPHIBIANS

• Frogs and Toads (4,000 species)
• 1. These animals are distinctive with
• their long hindlimbs capable of res-
• ponding to powerful muscles, which
• allow them to leap into the air.
• 2. Their success on land is due in part
• to the excellent prey-grasping
• capability of the tongue attached to the
• front of the mouth.

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REPTILES AMPHIBIANS

• 3. Frog skin has mucous glands, poison
• glands antibiotics that provide
• protection against pathogens in an
• aquatic habitat.
• 4. Scientists have noticed frog populations
• on the decline due to increases in
• parasitic attacks, predation, UV
• radiation, habitat losses chemical
• pollution.

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REPTILES AMPHIBIANS

• Frog versus Toad
• Frog has two bulging eyes
• strong, long, webbed hind feet that are adapted
  for leaping and swimming
• smooth or slimy skin (generally, frogs tend to
  like moister environments)
• Frogs tend to lay eggs in clusters.

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REPTILES AMPHIBIANS

• Frogs versus Toads
• Toads have stubby bodies with short hind legs
  (for walking instead of hopping)
• warty and dry skin (usually preferring dryer
  climates)
• paratoid (or poison) glands behind the eyes
• The chest cartilage of toads is different.
• Toads tend to lay eggs in long chains.

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REPTILES AMPHIBIANS

• Salamanders
• 1. Live in temperate zones in tropical
• areas of Central and South America
• numbering about 380 species
• 2. When they walk, the body bends from
• side to side, much like a fish moving
• through water.

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REPTILES AMPHIBIANS

• 3. Adults may retain larval features including
• gills and tail.
• 4. Some larvae may become sexually mature
• but not reach a true adult stage
• 5. Both forms, larval adult, are carnivorous.

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REPTILES AMPHIBIANS

• Caecilians
• 1. As amphibians evolved they lost their limbs
  vision, but not their prey-capturing jaws.
• 2. These unusual creatures live burrowed
• in the forest floor where they hunt for
• invertebrate prey.
• 3. Most of the 160 species burrow through the
  soil,
• using touch smell to pursue insects
  earthworms. The few aquatic types use
  electrical cues.

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REPTILES AMPHIBIANS

• Summary of amphibians
• They are vertebrates
• they have bony endoskeleton
• They have four legs
• Their body plan and mode of reproduction is
  somewhere between fishes and reptiles

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REPTILES AMPHIBIANS

• - Their transition to land involved
• development of legs
• more efficient lungs
• more efficient heart

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REPTILES AMPHIBIANS

• Because of this transition from water to land
• Amphibians had to contend with a drier habitat.
  This required a modified way to enhance oxygen
  uptake through their lungs
• This drier habitat required that they go
  back to a water environment for laying of eggs

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REPTILES AMPHIBIANS

• Legs, sufficient to support their body weight,
  allowed them to move from land to water when
  necessary.
• Their circulatory systems became more efficient
  to provide oxygen to all cells which, over time,
  increased the capacity for aerobic respiration
  and subsequently greater production of ATP
  allowing for more activities.

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REPTILES AMPHIBIANS

• Scientific Classification of Reptiles
• Kingdom AnimaliaPhylum ChordataSubphylum
  VertebrataClass Sauropsida

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REPTILES AMPHIBIANS

• REPTILES
• Reptiles are tetrapods and amniotes, animals
  whose embryos are surrounded by an amniotic
  membrane. Today they are represented by four
  surviving orders
• Crocodilia (crocodiles, caimans and alligators)
  23 species
• Rhynchocephalia (tuataras from New Zealand) 2
  species
• Squamata (lizards, snakes and amphisbaenids
  ("worm-lizards")) approximately 7,600 species
• Testudines (turtles) approximately 300 species

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REPTILES AMPHIBIANS

• Reptiles are found on every continent except for
  Antarctica, although their main distribution
  comprises the tropics and subtropics. Though all
  cellular metabolism produces some heat, modern
  species of reptiles do not generate enough to
  maintain a constant body temperature and are thus
  referred to as "cold-blooded" (ectothermic).

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REPTILES AMPHIBIANS

• Sea Turtle for an exception a reptile that
  elevates its body temperature well above that of
  its surroundings. Normally they rely on gathering
  and losing heat from the environment to regulate
  their internal temperature, e.g, by moving
  between sun and shade, or by preferential
  circulation moving warmed blood into the body
  core, while pushing cool blood to the periphery

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REPTILES AMPHIBIANS

• Reptiles evolved from tailed amphibian ancestors.
  There are nearly 8000 species that are divided
  into four orders snakes and lizards, crocodiles
  and alligators, tortoises and turtles, and
  tuataras.
• A reptile has the following features
• cold blooded
• dry, scaly skin
• tough shell on eggs
• eggs are laid on land

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REPTILES AMPHIBIANS

• The Rise of Amniotes - Reptiles
• During the late Carboniferous, amphibians
• gave rise to the amniotes (birds, reptiles,
  mammals).
• A. Four features were critical to amniotes
• escape from water dependency
• 1. They produce amniote eggs with internal
• covering membranes and a shell, which allow
• the eggs to survive in dry habitats.

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REPTILES AMPHIBIANS

• Amniote egg contains a membraneous sac that
  surrounds and protects the embryo.

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REPTILES AMPHIBIANS

• Allantois
• The word comes from the Greek word for
  sausage, which the allantois resembles. This
  sac-like structure is primarily involved in
  respiration and excretion, and is webbed with
  blood vessels. It is primarily found in the
  blastocyst stage of early embryological
  development, and its purpose is to collect liquid
  waste from the embryo.

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REPTILES AMPHIBIANS

• The structure first evolved in reptiles and birds
  as a reservoir for nitrogenous waste, but also as
  a means for oxygenation of the embryo. Oxygen is
  absorbed by the allantois through the egg shell .
  The allantois functions similarly in monotremes,
  which are egg-laying mammals.

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REPTILES AMPHIBIANS

• In most marsupials, the allantois is avascular,
  having no blood vessels, but still serves the
  purpose of storing nitrogenous waste. Also, most
  marsupial allantoises do not fuse with the
  chorion.
• In placental mammals, the allantois is the
  precursor of the mature umbilical cord

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REPTILES AMPHIBIANS

• 2. First vertebrates to form eggs with
• internal membranes that conserve
• H2O and cushion an embryo, and
• metabolically support it.
• 3. Amniotes have a toughened, dry or
• scaly skin that is resistant to drying.

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REPTILES AMPHIBIANS

• 4. They have a copulatory organ that
• permits internal fertilization.
• 5. Their kidneys are good at conserving
• water.
• Again, these amniotes (mammals, turtles,
  lizards, snakes, crocodiles birds) are the only
  tetrapods that can reproduce successfully away
  from aquatic habitats, while having the embryos
  develop to advanced stage before hatching or
  being born in a dry habitat.

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REPTILES AMPHIBIANS

• Reptiles demonstrate certain advantageous
  features compared to amphibians.
• 1. Modification of limb bones, teeth, and
• jaw bones allowed greater exploitation
• of the insect life emerging in the Late
• Carboniferous.
• 2. Development of the cerebral cortex permitted
• greater integration of sensory input and
  motor
• response.

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REPTILES AMPHIBIANS

• 3. A four-chambered heart fully separated
• into two halves and more efficient lungs
• allowed greater activity. Crocodilians
• were the first to exhibit this feature.
• Though the reptiles brain is small
• compared to its body mass, behavior
• governed by it is advanced to that seen
• in Amphibians.
• 4. Descendants of the surviving dinosaurs
• became the lineage of reptiles.

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REPTILES AMPHIBIANS

• 5. Transdermal gas exchange seen in
• amphibians is abandoned by
• reptiles because of their well develop-
• ed lungs.

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REPTILES AMPHIBIANS

• Circulatory systems
• Fish Amphibian Reptile, Bird
• 
  Mammal

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REPTILES AMPHIBIANS

• Humans, birds, and mammals have a 4-chambered
  heart that completely separates oxygen-rich and
  oxygen-depleted blood. Fish have a 2-chambered
  heart in which a single-loop circulatory pattern
  takes blood from the heart to the gills and then
  to the body. Amphibians have a 3-chambered heart
  with two atria and one ventricle.

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REPTILES AMPHIBIANS

• A loop from the heart goes to the pulmonary
  capillary beds, where gas exchange occurs. Blood
  then returns to the heart. Blood exiting the
  ventricle is diverted, some to the pulmonary
  circuit, some to systemic circuit. The
  disadvantage of the three-chambered heart is the
  mixing of oxygenated and deoxygenated blood.
  Reptiles, all birds and mammals, have a
  4-chambered heart, with complete separation of
  both systemic and pulmonary circuits.

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REPTILES AMPHIBIANS

• A Sampling of Existing Reptiles (Latin, to
  creep)
• Reptiles are a diverse group. They are
  considered an animal because they have basic
  amniote traits but not those of mammals or birds.
• A. Turtles
• 1. The distinctive shell offers protection
  while
• conserving water and body heat.

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REPTILES AMPHIBIANS

• 2. The shell is connected to the skeleton.
  Their teeth are tough, horny plates
  designed for gripping chewing
• food.
• 3. Turtles lay their eggs on land, where
• predation is high.

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REPTILES AMPHIBIANS

• Anatomy of a Box Turtle

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REPTILES AMPHIBIANS

• Turtle shell structure

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REPTILES AMPHIBIANS

• Turtle eggs and newborn

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REPTILES AMPHIBIANS

• Lizards
• 1. Most lizards are small-bodied insect
• eaters their most usual habitats are
  deserts
• and tropical forests.
• 2. Lizards are also prey for many other
  animals,
• but are quick in movement and have the
• unique ability to sever their own tails if
  it is
• grabbed by a predator.

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REPTILES AMPHIBIANS

• Lizards

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REPTILES AMPHIBIANS

• Scientific classification
• Kingdom AnimaliaPhylum ChordataClass
  SauropsidaOrder SquamataSuborder Lacertilia

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REPTILES AMPHIBIANS

• Snakes
• 1. Snakes are limbless but retain vestiges
• of hind limbs they are excellent
• predators.
• 2. Snakes have the ability to swallow prey
• larger than they are due to flexible skull
• and jaw bones.
• 3. All snakes are carnivores. Some suffocate
  their
• prey, and some kill their prey with venom.

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REPTILES AMPHIBIANS

• 95 of all living reptiles are composed of
  Lizards and Snakes.

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REPTILES AMPHIBIANS

• Tuataras
• 1. Although they resemble lizards, they
• are evolutionarily more ancient. They
• resemble amphibians with the brain
• and the way they walk.
• 2. They do not engage in sex until they
• are twenty years old!.

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REPTILES AMPHIBIANS

• 3. Only two species remain today
• they live on islands off the shore of
• New Zealand.
• 4. Like lizards, tuatarus have a 3rd eye
• under the skin with a retina, a lens,
• and nerves to the brain. They also
• may live to be 60 years old.

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REPTILES AMPHIBIANS

• Scientific Classification of Tuataras
• Kingdom AnimaliaPhylum ChordataClass
  SauropsidaOrder SphenodontiaFamily
  SphenodontidaeGenus Sphenodon

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REPTILES AMPHIBIANS

• Crocodilians
• 1. Crocodiles and alligators all live in or
• near water.
• 2. They are the largest living reptiles.
• 3. The body plan includes a long snout
• body temperature is regulated behavior-
• ally (ectothermic).

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REPTILES AMPHIBIANS

• 4. The ventricle of the heart is divided
• into right and left chambers more
• like the heart of birds than that of
• other reptiles.

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REPTILES AMPHIBIANS

• 4. Like other reptiles and birds, crocodilians
  adjust body temperature with behavioral
  and physiological mechanisms.
• 5. They are like birds in displaying complex
  social behaviors, such as parents guarding
  nests
• and assisting hatchlings into water. This
  trait
• and others suggest that crocodilians and
  birds
• share a common ancestor.

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REPTILES AMPHIBIANS

• Reptilian Orders
• Procolophonida (extinct)
• Araeoscelidia (extinct)
• Avicephala (extinct)
• Younginiformes (extinct)
• Ichthyopterygia (extinct)
• Placodontia (extinct)
• Nothosauria (extinct)

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• Orders (cont.)
• Plesiosauria (extinct)
• Prolacertiformes (extinct)
• Pterosauria (extinct)
• Saurischia (extinct)
• Ornithischia (extinct)

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REPTILES AMPHIBIANS

• Reptilian Orders (cont.)
• Testudines
• Squamata
• Sphenodontia
• Crocodilia

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REPTILES AMPHIBIANS

• Kingdom AnimaliaPhylum ChordataSubphylum
  VertebrataClass AmphibiaSubclasses and Orders
• Order Temnospondyli- extinctSubclass
  Lepospondyli- extinctSubclass Lissamphibia Order
  s Anura   Caudata   Apoda

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• Reading Assignment
• Pages 338-342 Chap. 20
• Pages 444-457 Chap. 26
• Pages 758-759 Chap. 43
• Appendix I Kingdom Animalia
• - tetrapods
• - amniotes