reptiles. first truly terrestrial vertebrates ~7000 species worldwide ~300 species in u.s. and...

ReptilesReptiles

ReptilesReptiles

First truly terrestrial vertebrates

~7000 species worldwide

~300 species in U.S. and Canada

First truly terrestrial vertebrates

~7000 species worldwide

~300 species in U.S. and Canada

ReptilesReptiles

Probably best remembered for what they once were, rather than what they are now

Mesozoic era - age of reptiles

Dominant group for >150 millions years

Probably best remembered for what they once were, rather than what they are now

Mesozoic era - age of reptiles

Dominant group for >150 millions years

ReptilesReptiles

12 or so principal groups of reptiles evolved

Only 4 groups remain today

12 or so principal groups of reptiles evolved

Only 4 groups remain today

Order SquamataOrder Squamata

Snakes and lizards >5800 species Most successful

group

Snakes and lizards >5800 species Most successful

group

Order CrocodiliaOrder Crocodilia

Crocodiles, alligators, caiman

~25 species Have survived for 200

million years Today: concerns that

humans may drive them to extinction

Crocodiles, alligators, caiman

~25 species Have survived for 200

million years Today: concerns that

humans may drive them to extinction

Order Chelonia (Testudines)Order Chelonia (Testudines)

Turtles ~330 species Ancient group that

survived, remained mostly unchanged from early ancestors

Turtles ~330 species Ancient group that

survived, remained mostly unchanged from early ancestors

Order RhynchocephaliaOrder Rhynchocephalia

Snout head or tuatara Only 1 species From New Zealand -

sole surviving species of ancestral stock

Snout head or tuatara Only 1 species From New Zealand -

sole surviving species of ancestral stock

Reptilian CharacteristicsReptilian Characteristics

Tough, dry scaly skin Protection against

desiccation, physical injury

Thin epidermis shed periodically

Much thicker dermis with chromatophores

Tough, dry scaly skin Protection against

desiccation, physical injury

Thin epidermis shed periodically

Much thicker dermis with chromatophores


Dermis converted into snakeskin, alligator leather for shoes, purses, and so on

Scales of keratin (epidermal)

Not homologous to bony, dermal fish scales

Dermis converted into snakeskin, alligator leather for shoes, purses, and so on

Scales of keratin (epidermal)

Not homologous to bony, dermal fish scales


Crocodilian scales remain throughout life

Grow gradually to replace wear

Crocodilian scales remain throughout life

Grow gradually to replace wear


In snakes and lizards, new scales grow beneath old

Old scales shed with old skin

In snakes and lizards, new scales grow beneath old

Old scales shed with old skin


Turtles add new layers of keratin under old layers of the plate-like scutes (modified scales)

Turtles add new layers of keratin under old layers of the plate-like scutes (modified scales)

SheddingShedding

Snakes turn old skin (scales, epidermis) inside out when shedding

Snakes turn old skin (scales, epidermis) inside out when shedding

SheddingShedding

Lizards split skin and leave it right side out, or slough it off in pieces

Lizards split skin and leave it right side out, or slough it off in pieces

Amniotic EggAmniotic EggChorioallantoicmembrane

Amniotic EggAmniotic Egg

Reptiles are able to lay their eggs in sheltered locations on land

Young hatch as lung-breathing juveniles, not aquatic larvae

Reptiles are able to lay their eggs in sheltered locations on land

Young hatch as lung-breathing juveniles, not aquatic larvae

Amniotic EggAmniotic Egg

Amniotic egg widened division between amphibians and reptiles

Probably greatly contributed to decline of amphibians and rise of reptiles

Amniotic egg widened division between amphibians and reptiles

Probably greatly contributed to decline of amphibians and rise of reptiles

Reptile JawsReptile Jaws

Reptile jaws designed for crushing prey

Fish, amphibian jaws designed for quick closure, but little force after

Reptile jaw muscles larger, longer, arranged for better mechanical advantage

Reptile jaws designed for crushing prey

Fish, amphibian jaws designed for quick closure, but little force after

Reptile jaw muscles larger, longer, arranged for better mechanical advantage

Reptile Copulatory OrganReptile Copulatory Organ

Copulatory organ permitting internal fertilization

Internal fertilization required for a shelled egg

Copulatory organ formed from an evagination of cloaca

Copulatory organ permitting internal fertilization

Internal fertilization required for a shelled egg

Copulatory organ formed from an evagination of cloaca

Reptile CirculationReptile Circulation

More efficient circulatory system, higher blood pressure

All reptiles have at least an incomplete separation of the ventricles

Flow patterns prevent mixing

More efficient circulatory system, higher blood pressure

All reptiles have at least an incomplete separation of the ventricles

Flow patterns prevent mixing

Reptile CirculationReptile Circulation

Crocodilians have two completely separated ventricles

All reptiles have two functionally separate circulations

Crocodilians have two completely separated ventricles

All reptiles have two functionally separate circulations

Reptile LungsReptile Lungs

Improved lungs Depend almost

exclusively on lungs for gas exchange

Supplemented by pharyngeal membrane respiration in some aquatic turtles

Improved lungs Depend almost

exclusively on lungs for gas exchange

Supplemented by pharyngeal membrane respiration in some aquatic turtles

Reptile LungsReptile Lungs

Lungs have larger respiratory surface than in amphibians

Air sucked into lungs rather then forced in by mouth muscles

Negative pressure Skin breathing

completely abandoned

Lungs have larger respiratory surface than in amphibians

Air sucked into lungs rather then forced in by mouth muscles

Negative pressure Skin breathing

completely abandoned

Reptile KidneyReptile Kidney

Kidneys more advanced (metanephric)

Very efficient at conserving water

Excretes uric acid (rather than urea, ammonia)

A semisolid paste

Kidneys more advanced (metanephric)

Very efficient at conserving water

Excretes uric acid (rather than urea, ammonia)

A semisolid paste

Better Body SupportBetter Body Support

Limbs better design for walking on land More ventral, less lateral Many dinosaurs walked on only hindlimbs

Limbs better design for walking on land More ventral, less lateral Many dinosaurs walked on only hindlimbs

Nervous SystemNervous System

Much more advanced - relatively larger cerebrum

CNS connections more advanced - permit complex behaviors not found in amphibians

Much more advanced - relatively larger cerebrum

CNS connections more advanced - permit complex behaviors not found in amphibians

Nervous SystemNervous System

Sense organs generally well-developed Hearing generally poorly developed in most

Sense organs generally well-developed Hearing generally poorly developed in most

Order CheloniaOrder Chelonia

Turtles Very ancient group Little change in

morphology since Triassic period

Turtles Very ancient group Little change in

morphology since Triassic period


Body enclosed in shell

Dorsal carapace Ventral plastron

Body enclosed in shell

Dorsal carapace Ventral plastron


Thoracic vertebrae and ribs built into shell

Shell of two layers Inner of bone Outer of keratin New keratin

deposited under old as turtle grows, ages

Thoracic vertebrae and ribs built into shell

Shell of two layers Inner of bone Outer of keratin New keratin

deposited under old as turtle grows, ages


Jaws lack teeth Equipped with tough,

horny plates for gripping, chewing food

Jaws lack teeth Equipped with tough,

horny plates for gripping, chewing food


Respiration poses a problem

Shell prevents expansion of chest for breathing

Adapted to use certain abdominal, pectoral muscles as a “diaphragm”

Respiration poses a problem

Shell prevents expansion of chest for breathing

Adapted to use certain abdominal, pectoral muscles as a “diaphragm”


Air drawn in by contracting limb flank muscles to make body cavity larger

Exhalation also active - shoulder muscles contracted, viscera compressed, air forced out of lungs

Air drawn in by contracting limb flank muscles to make body cavity larger

Exhalation also active - shoulder muscles contracted, viscera compressed, air forced out of lungs


Deformable plastron in snappers allows some elastic recovery during exhalation

Compressive force of water against body also can force air out

Deformable plastron in snappers allows some elastic recovery during exhalation

Compressive force of water against body also can force air out


Many water turtles acquire enough O2 when inactive by pumping water in and out of mouth

Pharyngeal breathing Can stay submerged

for extended periods Must lung breathe more

frequently when active

Many water turtles acquire enough O2 when inactive by pumping water in and out of mouth

Pharyngeal breathing Can stay submerged

for extended periods Must lung breathe more

frequently when active


Nervous system - tiny brain Typical of most reptiles Never exceeding 1% of body weight, but cerebrum

larger than in amphibians Turtle can learn, as quickly as a rat, to run a maze

Nervous system - tiny brain Typical of most reptiles Never exceeding 1% of body weight, but cerebrum

larger than in amphibians Turtle can learn, as quickly as a rat, to run a maze


Have both middle & inner ear, but sound perception is poor

Turtles are virtually mute

Tortoises may grunt or roar

Have both middle & inner ear, but sound perception is poor

Turtles are virtually mute

Tortoises may grunt or roar


Poor hearing compensated for by: Good sense of

smell Acute vision Color perception as

good as that of humans

Poor hearing compensated for by: Good sense of

smell Acute vision Color perception as

good as that of humans


Mating & reproduction Many varieties of

courtship Males of aquatic

species may swim around looking for proper leg stripe pattern

Pheromones also Males use claws

Mating & reproduction Many varieties of

courtship Males of aquatic

species may swim around looking for proper leg stripe pattern

Pheromones also Males use claws


Terrestrial species may vocalize

Males may track females (pheromones) for days

Terrestrial species may vocalize

Males may track females (pheromones) for days


Males may mark territory with fecal pellets

Courtship involves rubbing limbs against scent glands (underside of jaw) and sniffing

Males may mark territory with fecal pellets

Courtship involves rubbing limbs against scent glands (underside of jaw) and sniffing


Biting, ramming, hooking are directed at other males

Biting - head & limbs Ramming - rearing

up, smacking shells Hooking - bulldozing

under plastron to flip or hurry

Biting, ramming, hooking are directed at other males

Biting - head & limbs Ramming - rearing

up, smacking shells Hooking - bulldozing

under plastron to flip or hurry


Turtles are oviparous

Fertilization is internal, and all species bury eggs in ground in nests

4 to >100 eggs

Turtles are oviparous

Fertilization is internal, and all species bury eggs in ground in nests

4 to >100 eggs


Exercise care in constructing nest

Deposit eggs and abandon them

Incubation 1-14 months

40-60 days most typical

Exercise care in constructing nest

Deposit eggs and abandon them

Incubation 1-14 months

40-60 days most typical


Movements to nesting areas very faithful

Terrestrial species use familiarity with area, sun

Marine species use variety of mechanisms to traverse large distances

Movements to nesting areas very faithful

Terrestrial species use familiarity with area, sun

Marine species use variety of mechanisms to traverse large distances


Earth’s magnetic field Polarized light Sun & stars Low frequency

sounds Green sea turtles find

Ascension Island (20 km) in mid-Atlantic from coastal Brazil - 2200 km

Earth’s magnetic field Polarized light Sun & stars Low frequency

sounds Green sea turtles find

Ascension Island (20 km) in mid-Atlantic from coastal Brazil - 2200 km


Size - marine turtles largest

Buoyed by aquatic environment

May reach 2 m in length, 725 kg in weight

Biggest species is leatherback

Size - marine turtles largest

Buoyed by aquatic environment

May reach 2 m in length, 725 kg in weight

Biggest species is leatherback


Green sea turtle may exceed 360 kg

Economically valuable - heavily exploited - rarely gets to large size

Green sea turtle may exceed 360 kg

Economically valuable - heavily exploited - rarely gets to large size


Land tortoises generally not as large as aquatic forms

Some may weigh several hundred kg

Giant tortoises of Galapagos Islands among world’s largest terrestrial turtles

Land tortoises generally not as large as aquatic forms

Some may weigh several hundred kg

Giant tortoises of Galapagos Islands among world’s largest terrestrial turtles


Lifespan - turtles are most long-lived vertebrates

Individuals of at least 5 species known to live 100 years or longer

Some believed to have lived more than 150 years

Lifespan - turtles are most long-lived vertebrates

Individuals of at least 5 species known to live 100 years or longer

Some believed to have lived more than 150 years


Longevity attributed to slow rate of metabolism

Galapagos tortoise top speed: 300 m/hr

Reports of box turtle caught in U.S. with “1850” carved into plastron Skepticism!

Longevity attributed to slow rate of metabolism

Galapagos tortoise top speed: 300 m/hr

Reports of box turtle caught in U.S. with “1850” carved into plastron Skepticism!


Protective shell Head, appendages

can be drawn in for protection

Box turtles especially good because of hinged plastron

Protective shell Head, appendages

can be drawn in for protection

Box turtles especially good because of hinged plastron


Shell not as protective in many species

Soft, leather-like in softshell turtles

Shell not as protective in many species

Soft, leather-like in softshell turtles


Shell too small for protection in other species, e.g., snappers

Other means of defense - ferocious, short-tempered

“Tigers of the pond”

Shell too small for protection in other species, e.g., snappers

Other means of defense - ferocious, short-tempered

“Tigers of the pond”


Entirely carnivorous - fish, frogs, ducks, whatever they can catch

Alligator snapper hides on bottom and waves worm-like tongue to attract fish

Wholly aquatic - come ashore only to lay eggs

Entirely carnivorous - fish, frogs, ducks, whatever they can catch

Alligator snapper hides on bottom and waves worm-like tongue to attract fish

Wholly aquatic - come ashore only to lay eggs

Turtle ConservationTurtle Conservation

Slow growth, long time to maturity predispose many species to risk of extinction

Changing conditions may increase adult mortality, juvenile recruitment

Slow growth, long time to maturity predispose many species to risk of extinction

Changing conditions may increase adult mortality, juvenile recruitment


Problem severe for large tortoises, sea turtles

Largest, slowest-growing

Human and animal invasion of beaches, isolated island habitats

Problem severe for large tortoises, sea turtles

Largest, slowest-growing

Human and animal invasion of beaches, isolated island habitats


Herbivores compete with tortoises for limited vegetation

Eggs, young fall prey to dogs, cats, rats

Herbivores compete with tortoises for limited vegetation

Eggs, young fall prey to dogs, cats, rats


Protection of land tortoises simpler than protection of sea turtles

Limited range (single island) defines limits where protection is needed

Protection of land tortoises simpler than protection of sea turtles

Limited range (single island) defines limits where protection is needed


Sea turtles range over international, national borders

Limited number of breeding sites

Problems with exploitation - controlled or outright ban?

Sea turtles range over international, national borders

Limited number of breeding sites

Problems with exploitation - controlled or outright ban?


Ocean plastics pollution - bags look like natural jellyfish prey

Not enough known about biology do devise protective management program

Tag a turtle? 2000 X

Ocean plastics pollution - bags look like natural jellyfish prey

Not enough known about biology do devise protective management program

Tag a turtle? 2000 X


“characterized by scales”

Lizards, snakes, worm lizards

Most recent products of reptile evolution

Most successful - 95% of known living species of reptiles

“characterized by scales”

Lizards, snakes, worm lizards

Most recent products of reptile evolution

Most successful - 95% of known living species of reptiles


Lizards began diversifying at time when dinosaurs were near end of their dominance

Were successful because of adaptability

Adopt various body forms, occupy various habitats

Lizards began diversifying at time when dinosaurs were near end of their dominance

Were successful because of adaptability

Adopt various body forms, occupy various habitats


Snakes likely arose from group of lizards whose descendents include monitor lizards, but fossil record poor

Snakes likely arose from group of lizards whose descendents include monitor lizards, but fossil record poor


Legless character apparently evolved as adaptation to burrowing lifestyle

Snakes since have radiated into terrestrial, aquatic, arboreal niches

Legless character apparently evolved as adaptation to burrowing lifestyle

Snakes since have radiated into terrestrial, aquatic, arboreal niches


Two adaptations characterize snakes:

Extreme body elongation - displacement, rearrangement of organs

Highly mobile jaws - swallow prey larger than own diameter

Two adaptations characterize snakes:

Extreme body elongation - displacement, rearrangement of organs

Highly mobile jaws - swallow prey larger than own diameter


Two suborders:

Sauria - lizards “lizard”

Serpentes - snakes “to creep”

Two suborders:

Sauria - lizards “lizard”

Serpentes - snakes “to creep”

LizardsLizards

Very diversified group (3300 species)

Terrestrial, burrowing, aquatic, arboreal, aerial

Many familiar groups:

Very diversified group (3300 species)

Terrestrial, burrowing, aquatic, arboreal, aerial

Many familiar groups:

LizardsLizards

Geckos

Mostly small, nocturnal, with adhesive toe pads (walk anywhere)

Geckos

Mostly small, nocturnal, with adhesive toe pads (walk anywhere)

LizardsLizards

Iguanas

Often bright-colored New World lizards

Marine iguana - only marine lizard in world

Iguanas

Often bright-colored New World lizards

Marine iguana - only marine lizard in world

LizardsLizards

Skinks

Elongate bodies, reduced limbs

Skinks

Elongate bodies, reduced limbs

LizardsLizards

Chameleons

Arboreal

Tongue flicked to greater distance than body length

Prehensile tail Zygodactylous feet

Chameleons

Arboreal

Tongue flicked to greater distance than body length

Prehensile tail Zygodactylous feet

LizardsLizards

Independently moveable eyes elevated on cones - good eyesight - gauge distance accurately

Independently moveable eyes elevated on cones - good eyesight - gauge distance accurately

LizardsLizards

Lizard body form not as distinctive as other reptiles

Many functional, behavioral modifications

e.g., degenerate or absent limbs - no good in dense grass

Lizard body form not as distinctive as other reptiles

Many functional, behavioral modifications

e.g., degenerate or absent limbs - no good in dense grass

LizardsLizards

Differ from snakes:

Halves of lower jaw firmly united at mandibular symphysis

Teeth, but not developed into fangs

Differ from snakes:

Halves of lower jaw firmly united at mandibular symphysis

Teeth, but not developed into fangs

LizardsLizards

Moveable eyelids (snake eyes covered with permanent, transparent cap)

Keen daylight vision

Moveable eyelids (snake eyes covered with permanent, transparent cap)

Keen daylight vision

LizardsLizards

Size - 3 cm to 3 m

Hawaiian gecko

Komodo dragon 75 kg

Fossils: 5.5 m, >1000 kg

Size - 3 cm to 3 m

Hawaiian gecko

Komodo dragon 75 kg

Fossils: 5.5 m, >1000 kg

LizardsLizards

80% of lizards are <20 g in weight

Generally insectivorous (opportunistic), although some specialists

N. Amer. horned lizards eat only ants

80% of lizards are <20 g in weight

Generally insectivorous (opportunistic), although some specialists

N. Amer. horned lizards eat only ants

LizardsLizards

Most large lizards are herbivores

Trees in tropics, ground vegetation on oceanic islands, seaweed in ocean

Most large lizards are herbivores

Trees in tropics, ground vegetation on oceanic islands, seaweed in ocean

LizardsLizards

Monitor lizards are exception to vegetarians

Food of vertebrates (birds, mammals), invertebrates

Komodo - ambush predator on large mammals (deer, goats, water buffalo)

Monitor lizards are exception to vegetarians

Food of vertebrates (birds, mammals), invertebrates

Komodo - ambush predator on large mammals (deer, goats, water buffalo)

LizardsLizards

Foraging strategies:

Sit and wait (insects come to them)

Active foragers (move to encounter prey)

Foraging strategies:

Sit and wait (insects come to them)

Active foragers (move to encounter prey)

LizardsLizards

Foraging modes alternate at successive levels of food chain

Moving insect -> sit-and-wait lizard -> active predator

Sitting insect -> active lizard -> sit-and-wait predator

Foraging modes alternate at successive levels of food chain

Moving insect -> sit-and-wait lizard -> active predator

Sitting insect -> active lizard -> sit-and-wait predator

LizardsLizards

May use territorial and courtship behaviors

Male anoles have gular fan (dewlap) for conspicuous displays

Skin distended by hyoid apparatus

May use territorial and courtship behaviors

Male anoles have gular fan (dewlap) for conspicuous displays

Skin distended by hyoid apparatus

LizardsLizards

Behaviors include:

Extending, contracting fan

Pushups Bobbing head

Behaviors include:

Extending, contracting fan

Pushups Bobbing head

LizardsLizards

Territories defended by males for access to females (bite & chase, but no fighting)

Females have non-overlapping home ranges for feeding

Male territory includes several females - mates with all

Territories defended by males for access to females (bite & chase, but no fighting)

Females have non-overlapping home ranges for feeding

Male territory includes several females - mates with all

LizardsLizards

Mate by pressing cloacal regions together

Males grip female’s neck, shoulders

Males have paired copulatory organs - hemipenes - to aid sperm transfer

Mate by pressing cloacal regions together

Males grip female’s neck, shoulders

Males have paired copulatory organs - hemipenes - to aid sperm transfer

LizardsLizards

Range of reproductive modes from oviparity to viviparity

Skinks - eggs retained in oviducts, receive nutrients across a “placenta”

Range of reproductive modes from oviparity to viviparity

Skinks - eggs retained in oviducts, receive nutrients across a “placenta”

LizardsLizards

All-female (parthenogenetic) species occur in at least 6 families

Especially common among racerunners (Teiidae)

Diploids and triploids known

All-female (parthenogenetic) species occur in at least 6 families

Especially common among racerunners (Teiidae)

Diploids and triploids known

LizardsLizards

High reproductive potential - every individual capable of producing offspring

Can repopulate habitat faster than bisexual species after flood, other disaster

High reproductive potential - every individual capable of producing offspring

Can repopulate habitat faster than bisexual species after flood, other disaster

LizardsLizards

Parental care

Many lizards remain with eggs or nest site

Little if any care given after young hatch or are born

Parental care

Many lizards remain with eggs or nest site

Little if any care given after young hatch or are born

Suborder Serpentes - SnakesSuborder Serpentes - Snakes

2300 species 10 cm long up to 10

m long Highly specialized

body form

2300 species 10 cm long up to 10

m long Highly specialized

body form


Entirely limbless Lack pectoral, pelvic

girdles (except vestige of latter in pythons, boas)

Short, wide vertebrae for quick lateral undulations

Ribs improve rigidity

Entirely limbless Lack pectoral, pelvic

girdles (except vestige of latter in pythons, boas)

Short, wide vertebrae for quick lateral undulations

Ribs improve rigidity


Rearranged internal anatomy

Left lung reduced or absent

Gall bladder posterior to liver

Right kidney anterior to left

Gonads similarly displaced

Rearranged internal anatomy

Left lung reduced or absent

Gall bladder posterior to liver

Right kidney anterior to left

Gonads similarly displaced


Little modification for various lifestyles:

Elongate for arboreal Shorten for burrowing Broaden for

swallowing big prey Compress laterally for

swimming

Little modification for various lifestyles:

Elongate for arboreal Shorten for burrowing Broaden for

swallowing big prey Compress laterally for

swimming

Snake Sense OrgansSnake Sense Organs

Snake, lizard eyes different: focusing, retina morphology

Re-evolved from burrowing ancestors

Permanent transparent covering - non-blinking stare

Lack of eyeball mobility Poor vision - except

binocular in arboreal snakes

Snake, lizard eyes different: focusing, retina morphology

Re-evolved from burrowing ancestors

Permanent transparent covering - non-blinking stare

Lack of eyeball mobility Poor vision - except

binocular in arboreal snakes


Hearing - no obvious external ear

No obvious response to aerial sounds

Not deaf - have internal ears - hearing similar to lizards

Sensitive to vibrations carried in ground

Hearing - no obvious external ear

No obvious response to aerial sounds

Not deaf - have internal ears - hearing similar to lizards

Sensitive to vibrations carried in ground


Olfaction important, but not in nostrils

Jacobson’s organs (vomeronasal organs)

Tongue carries scent particles to organ

Olfaction important, but not in nostrils

Jacobson’s organs (vomeronasal organs)

Tongue carries scent particles to organ

Snake FeedingSnake Feeding

Skull, jaws highly specialized for feeding

Eat prey several times their own diameter

Non-joined mandibles Loose skull bones Tracheal opening far

forward between mandibles

Skull, jaws highly specialized for feeding

Eat prey several times their own diameter

Non-joined mandibles Loose skull bones Tracheal opening far

forward between mandibles


Prey swallowed head first

Pulled in by teeth, jaws, alternating side-to-side

Contractions of neck muscles force prey down digestive tract

Prey swallowed head first

Pulled in by teeth, jaws, alternating side-to-side

Contractions of neck muscles force prey down digestive tract


Two ways to subdue prey:

Constricting - grab prey in mouth and suffocate by looping body coils and tightening

Two ways to subdue prey:

Constricting - grab prey in mouth and suffocate by looping body coils and tightening


Venom - toxic concentrations in saliva

Neurotoxic - blindness, paralysis

Hemolytic - ruptures blood vessels, cells

Venom - toxic concentrations in saliva

Neurotoxic - blindness, paralysis

Hemolytic - ruptures blood vessels, cells


Poisonous snakes in 4 families

Viperidae - viper, pit vipers (heat sensitive)

Elapidae - coral snakes (inject venom by chewing)

Hydrophiidae - sea snakes

Colubridae - rear-fanged - venom to calm, not kill

Poisonous snakes in 4 families

Viperidae - viper, pit vipers (heat sensitive)

Elapidae - coral snakes (inject venom by chewing)

Hydrophiidae - sea snakes

Colubridae - rear-fanged - venom to calm, not kill


Sea snakes have most deadly venom

King cobra most dangerous, largest (5.5 m) - kill 9,000 people per year

Sea snakes have most deadly venom

King cobra most dangerous, largest (5.5 m) - kill 9,000 people per year

Snake LocomotionSnake Locomotion

4 basic types: Lateral undulation - S-

shaped path, pressure against surface irregularities

4 basic types: Lateral undulation - S-

shaped path, pressure against surface irregularities


Concertina movement - movement upward or along narrow passages

Extend forward while bracing S-shaped loops

Concertina movement - movement upward or along narrow passages

Extend forward while bracing S-shaped loops


Rectilinear movement - slow, straight-line movement

Rectilinear movement - slow, straight-line movement


Sidewinding - sandy surfaces, body thrown forward in loops, body at 60° angle to line of travel, 1 or 2 parts of body in contact with ground at once

Sidewinding - sandy surfaces, body thrown forward in loops, body at 60° angle to line of travel, 1 or 2 parts of body in contact with ground at once

Snake ReproductionSnake Reproduction

Most oviparous - lay eggs in protected areas

Most of remainder are ovoviviparous (including rattlesnakes)

Very few viviparous Females store sperm

from single mating, can lay several clutches over long interval

Most oviparous - lay eggs in protected areas

Most of remainder are ovoviviparous (including rattlesnakes)

Very few viviparous Females store sperm

from single mating, can lay several clutches over long interval


Unchanged for 160 million years

Crocodiles larger, more dangerous than alligators

Prey drowned, ripped into pieces by rapid rolling

No natural enemies

Unchanged for 160 million years

Crocodiles larger, more dangerous than alligators

Prey drowned, ripped into pieces by rapid rolling

No natural enemies


Oviparous - lay eggs in mass of vegetation

Guarded by mother Incubation temperature

determines sex of alligator hatchlings

Low - females High - males 5:1 (M:F) in some areas

Oviparous - lay eggs in mass of vegetation

Guarded by mother Incubation temperature

determines sex of alligator hatchlings

Low - females High - males 5:1 (M:F) in some areas


Vocalizations by hatchlings cause mother to open next, allow hatchlings to escape

Some adults carry young to water

Vocalizations by hatchlings cause mother to open next, allow hatchlings to escape

Some adults carry young to water


Mothers may guard young in pools for period of time to protect them from predators (fish, mammals)

Mothers may guard young in pools for period of time to protect them from predators (fish, mammals)

Order SphenodontaOrder Sphenodonta

Tuatara - single species in New Zealand

Lizard-like, <66 cm Lives in burrows Slow-growing, long-

lived (77 years)

Tuatara - single species in New Zealand

Lizard-like, <66 cm Lives in burrows Slow-growing, long-

lived (77 years)

Order SphenodontaOrder Sphenodonta

Living fossil - primitive features identical to fossilized forms

Primitive skull structure

Well-developed parietal eye with retina, lens on top of head (non-functional)

Living fossil - primitive features identical to fossilized forms

Primitive skull structure

Well-developed parietal eye with retina, lens on top of head (non-functional)

reptiles. first truly terrestrial vertebrates ~7000 species worldwide ~300 species in u.s. and...

Documents

old skin slide

chromatophores slide

wear slide

extinction slide

canada slide

old old scales

old skin scales

successful group slide