REPTILE CHARACTERISTICS: The Snakes

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REPTILE CHARACTERISTICSThe Snakes
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Extant Reptiles

• 15,800 species
• Testudines (Chelonia) 260
• Aves 8,700
• Squamates 6,850
• Crocodilians 2
• Tuatara 2

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Characterisitcs of Reptiles

• Scales with keratin help prevent water loss.
• 3-chambered heart except crocodilians.
• Almost all have lungs.
• Internal fertilization.
• Most reptiles lay shelled amniotic eggs on land.
• Some have young born alive (viviparous) with
  extraembryonic membranes forming placenta.
• Ectothermic and regulate body temperature.

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Characteristics of Snakes

• Diapsid skull.
• Replacement of teeth occurs through life.
• Reduction of bones in limbs.
• Pair of copulatory organs, hemipenes.
• Oviparity and viviparity occur.
• Shedding of epidermis occurs regularly.
• Reduced left lung.
• Transparent spectacle covers the eye.
• 120 400 precloacal vertebrae.

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Reptilian Skull Patterns
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Diapsid Skull
Python Skull
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Snake Teeth

• Teeth are superficially attached
• Acrodont if located on top of jaw
• Pleurodont if attached to outside edge of jaw
• Or firmly attached in sockets
• Thecodont
• Teeth are replaced
• because of wear and
• tear.

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Limbs of Snakes

• Not present ordinarily
• but in primitive
• snakes (Boidae), a
• rudimentary pelvic
• girdle is represented
• by cloacal spurs.

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Copulatory Organs Hemipenes
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Oviparous
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Emergence of young snakes
Viviparous
Oviparous
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Shedding of Skin Ecdysis
Shedding cycle
After shedding
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Spectacle of Eye
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Viperidae

• Vipers may be terrestrial or arboreal.
• Habitats range from rain forests to deserts and
  high mountains.
• Oviparous or viviparous.
• Representatives include rattlesnakes, eyelash
  vipers, bushmasters, fer-de-lances, copperheads.
• All produce venom.

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A Pit Viper Heat detecting pit located between
eye and nostril.
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Crotalus adamanteusEastern Diamondback
Rattlesnake
Crotalus
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Eastern Diamondback Rattlesnake
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Consuming a rabbit
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Presettlement habitat distribution of Crotalus
adamanteus was primarily open-canopied,
pyro-climax, pine dominated communities,
including longleaf pine/wiregrass sandhills and
clayhills, flatwoods, and sand pine scrub. The
species was also common in coastal strand and
palmetto prairie and utilized temperate hardwood
forest and tropical hardwood hammocks, especially
where these were adjacent to pine-dominated
habitats. Today C. adamanteus occurs in the few
remnants of the original habitats that remain
plus various ruderal situations such as berms
along canals and old-field successional habitats.
In the southern portion of its range, the species
is sympatric with the gopher tortoise. The
extensive burrows are used by C. adamanteus for
winter refuge sites. In the northern portion of
their range, stump holes are the preferred refuge
site. Crotalus adamanteus have large home ranges
that may encompass as much as 500 acres. Lives
10 years in the wild.
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Crotalus horridusTimber Rattlesnake (Canebreak)
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Warning Timber Rattlesnakes are large venemous
snakes whose bites can be fatal. Fortunatly,
Timber Rattlesnakes are generally not aggressive
and are often reluctant to even rattle.  This
attribute makes them the preferred species of
venomous snake used during snake handling
religious services.  However, if you encounter
this snake you should leave it alone. 
Description Timber Rattlesnakes range in size
between 3 and 5 ft. (.91-1.52 m) with males
attaining greater sizes than females.  The
coloration of this species is blackish,
yellowish, pinkish, or grayish with dark, bent,
cross bands aligned along the dorsal length of
its body.  A reddish dorsal stripe runs between
the crossbands and it has a black tail.  The
Timber Rattlesnake used to be divided into two
distinct subspecies Crotalus horridus horridus
(Timber Rattlesnake) and Crotalus horridus
atricaudatus (Canebrake Rattlesnake).  The
"Timber Rattlesnake" inhabits the Mountains and
it does not have a middorsal stripe.  The
"Canebrake Rattlesnake" lives in the Coastal
Plain and Piedmont.  Canebrakes have more dark
markings and they usually have a middorsal
stripe.  Herpetologists are debating whether or
not Crotalus horridus should be divided into two
subspecies, but the two "subspecies" are
currently not considered separate.
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Habitat/Range Timber Rattlesnakes inhabit
forest, nearby fields, swampy areas, and thickets
in the Appalachians, upper Piedmont, and Coastal
regions of the state.  It's range has been
reduced in the middle of the state and its
numbers have also decreased in many other areas.
Much of this decline can be attributed to loss of
habitat.  Contributing to this decline is the low
reproductive rate of female Timber Rattlesnakes.
Reproduction  They mate in the summer or fall
and give birth to 5 to 17 young during late
summer. Research by Bill Brown  showed that most
females do not reproduce until they are nine
years old.  In addition to delayed sexual
maturity, another factor that contributes to
their relatively low reproductive potential is
that most females only reproduce every three
years. Prey  Timber Rattlesnakes eat primarily
rodents but they may also eat birds.
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Canebrake Rattlesnake
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Eyelash ViperCentral, South America
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Agkistrodon piscivoorusCotton Mouth
Broad dark stripe present behind eye. Black
crossbands on lighter background.
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Cottonmouth
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Agkistrodon contortrixCopperhead
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Eastern Coral Snake