Snakes Suborder Serpentes

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Snakes (Suborder Serpentes) Morphology -head
scales- nasal, loreal, preoccular, upper labial,
postocular, lower labial, temporal body scales
are either keeled or non-keeled -on top of head-
rostral, internasal, prefrontal, supraocular,
frontal, parietal -ventrals- scutes on
venter -long slender limbless -brain totally
encased in skull (not lizards) -no nictitating
membrane -no osteoderms -absent temporal
arches -no urinary bladder -left lung is
reduced -no external ear canals -no remnants of
a sternum -lower jaws are mobile at mandibular
symphysis, expansion -kinetic skulls
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Comparative Characteristics
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Snake Phylogeny
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Family Anomalepididae Early Blindsnakes 4
genera 15 species. -mostly Central and N. South
America both jaws have teeth no pelvic girdle
at all feed on soft bodied insects oviparous qu
ite primitive
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Family Leptotyphlopidae Threadsnakes (or
Wormsnakes) 2 genera 90 species Southwest US,
S.Amer, Africa, Mid East blind snakes non
enlarged ventrals pelvic girdle remnants no
limb vestiges no brille no left lung no left
oviduct teeth on dentary, absent on
maxilla Leptotyphlops dulcis Texas
Blindsnakes look like worms defensive
secretions from cloaca, to combat
ants pheromone mimics ants and termites, ants
won't attack
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Family Typhlopidae Blindsnakes 6 genera 210
species -cosmopolitan most speciose blindsnakes
-no enlarged ventrals -tail is short,
terminates in spine -pelvic girdle remnants no
femurs eye is covered by head scales, no
brille-spectacle no teeth on dentary Typhlops
two and a half feet secretive no US
forms there are teeth on upper jaw feed on soft
bodied inverts oviparous or ovoviviparous some
lay eggs in termite nests
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Family Anomochilidae False Blindsnakes 1
genus 2 species Malay Peninsula, Sumatra,
Borneo Anomochilus -small snakes with short
tails -pelvic girdle vestiges hindlimb
vestiges appear externally -left lung reduced
-left and right oviducts well
developed -biology poorly known oviparous
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Family Uropeltidae Shieldtail snakes 9 genera
45 species fossorial eat earthworms cone-shape
d heads two ventrals per body segment forest
inhabitants
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Family Cylindrophiidae Pipesnakes 1 genus 8
species Cylindrophis Sri Lanka into SE
Asia medium to large hind limb vestiges as
cloacal spurs fossorial nocturnal
foragers viviparous head-tail mimicry as a
defense mechanism
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Family Aniliidae False Coralsnake -monotypic
Anilius scytale -vestigial hind limbs -600 mm
total length striking red and black
bands -fossorial eat amphisbaenids and other
snakes non venomous ovoviviparous
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Family Xenopeltidae Sunbeam Snakes 1 genus 2
species India, SE Asia, Indonesia colorful -
iridescent scales reflect sun no girdle
vestiges vertical eye pupils-nocturnal right
lung is half the size of the left lung body is
cylindrical Xenopeltus oviparous -up to 17
eggs semi-fossorial
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Family Loxocemidae Mesoamerican
Python monotypic family Southern Mexico to
Costa Rica Loxocemus bicolor moderate to large
(1.4 m) live in forested habitats possibly
burrowers forage at night eat variety of
inverts. and verts.
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Corallus
Family Boidae Boas true boas cosmopolitan
mostly tropical vestigial pelvic girdle and hind
limbs as cloacal spurs most boids possess
sensory labial pits viviparous arboreal or
terrestrial small dorsal scales
Boa
Eunectes
Epicrates
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Eunectes
2 subfamilies Boinae (6 genera 25
species) labial sensory pits Eunectes
murinus the largest snake - Anaconda 37 feet,
over 300 pounds N. Venezuela, Orinoco
River Boa constrictor cloacal spurs- hind
limb vestiges help with copulation 18
ft Erycinae (2 genera 14 species)
Eunectes
Charina bottae
sand boas, rosy boas, rubber boas semifossorial
snakes labial sensory pits absent Charina
bottae rubber boa Pacific northwest Charina
trivirgata rosy boa extreme southwest US
Charina trivirgata
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Python reticulatus
Family Pythonidae Pythons 4 genera 25
species large snakes interlabial infrared
pits Africa, Indo- Australia Python reticulatus
(2.5 10 m) (Reticulated python) over 100
eggs laid Morelia amethistina Australia 24
ft P. molurus (Burmese python) India 24
ft brood young facultative endothermy P.
sebae African Rock Python 24 ft
Python molurus
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Morelia spilota (Carpet python)
Morelia tracyae (Halmahera Scrub
Python) Indonesia (up to 11 ft.)
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Family Bolyeriidae Splitjaw Boas Mauritius
Islands two monotypic genera maxillary is
divided and hinged (unique feature among
snakes) lack pelvic girdle and limb elements
absent
Casarea dussumieri
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Tropidophis
Family Tropidophiidae Dwarf boas 3
subfamilies5 genera 23 species) Caribbean
Polynesia Tropical America (Shares traits with
both boids and colubroid snakes) pelvic
remnant present dentary lacks anterior
canine-like tooth in subfamily
Xenophidionae (1genus 2 species) Xenophidion
(spinejaw snake)
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Family Acrochordidae Wart Snakes 1 genus 3
species Indonesia, Australia, India Small-head
and thick-bodied snakes skin loose,
baggy -aquatic snakes similar to our
Nerodia small granular scales Acrochordus no
vestiges of limbs or girdles up to six
feet valued for skin recurved teeth,
pleurodont-on inside lining of teeth valved
nostrils
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Family Viperidae Vipers and Pitvipers 3
subfamilies cosmopolitan except
Australia (Subfamily Azemiopinae removed
recently) left lung absent no limb vestiges
large ventrals Venomous solenoglyphous-
retractable fangs hematoxic venom -sit and wait
predators Subfamily Viperinae (13 genera 65
species Europe to India and Africa True
vipers lack the pit of New World
vipers Vipera berus Eurasia 25
inches few have caused death Cerastes side
winder desert dweller nocturnal epidermal
horns above eyes Bitis gabonica Gaboon
Viper fangs can be almost 2 inches sit and
wait, non aggressive Bitis Puff
Adder more aggressive
Vipera berus
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Cerastes cerastes (desert horned viper)
Bitis gabonica
Bitis arietans
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Causus -night adders most primitive snake in
family colubrid-like Subfamily Crotalinae (18
genera 155 species) true pit vipers heat
sensitive loreal pit, between nasal and
preocculars homeothermic prey are followed by
heat trail give birth to live young Agkistrodon
contortrix Meshaka et al. found many local
females, recorded brood sizes, Trauth et al.
1994 measured ova, and yolk development sit and
wait, relatively docile A. piscivorus more
defensive, belligerent brood size is highly
variable
Causus
Agkistrodon piscivorus
Agkistrodon contortrix
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Crotalus atrox - Western Diamondback smaller
only than E. Diamondback in AR, 6 footers have
been recorded coon tail on big rattlers 1991,
paper on them seem to occur on larger Mts. in
Arkansas (C. T. McAllister bitten by captive
snake) C. adamanteus - Eastern Diamondback larges
t North American rattlesnake (Photo from Mount
1975) C. cerastes - Sidewinder C. horridus -
Timber rattlesnake completely black tail should
not be confused with atrox hematoxic as are the
others C. molossus - Black-tailed
Rattlesnake C. scutalatus - Mojave
Rattlesnake Sistrurus miliarius - Pygmy
rattlesnake common in hardwood cedar areas in
Ozarks
Crotalus atrox
Crotalus cerastes
Crotalus adamanteus (photo by R. Mount)
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Crotalus molossus (above left) Crotalus horridus
(above right) Crotalus scutulatus (right)
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Sistrurus miliarius
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Rattlesnakes of the United States
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Latin American Representatives Bothrops
atrox fer-de-lance quite large and
dangerous Lachesis muta bushmaster 12 ft in
length cryptic abundant in Central America
Bothrops atrox
11 yr old Equadorian boy bitten by a Bothrops
asper two weeks prior
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Family Atractaspididae Stiletto Vipers,
Burrowing Asps 2 subfamilies (13 genera 58
species) Sub-Saharan Africa and
Iran Atractaspis only lethal bite in
family feeds fossorially oviparous shiny body,
blunt snout, slender and cylindrical well feared
in rural Africa-vernacular names
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Nerodia rhombifer
Family Colubridae Colubrids Structurally diverse
taxa aglyphous dentition- non venomous
opisthoglyphous dentition- rear fanged
(boomslang) proteroglyphous-rigid fangs at the
front of the mouth (Elapidae) solenoglyphous-fron
t retractable fangs (vipers and pitvipers) catch
all family -largest snake family -cosmopolitan -le
ft lung reduced or absent -large ventrals no
vestige of pelvic girdle -some opisthoglyphous 7
subfamilies 300 genera 4 subfamilies are in the
USA (3 in Arkansas)
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Subfamily Colubrinae 100 genera 650
species -well represented in AR -typical
colubrids Coluber racer four subspecies in
AR C. constrictor priapus-So. Black C. c.
anthicus-Buttermilk Snake C. c.
latrunculus-Black Masked Racer C. c.
flaviventris Jonesboro is between latrunculus
and priapus H. Fitch- Lizards and Snakes, UK
NHR -Fitch Natural History Reservation Mastico
phis coachwhips M. flagellum fast and
long very defensive, cobra stance lizard and
bird eaters Pituophis catenifer Bullsnake (not
found in AR) Dasypeltis formerly a
subfamily egg eaters modified vertebral
processes cut through egg egg is consumed,
shell is regurgitated
Coluber constrictor
Pituophis
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Cemophora Scarlet Snake eat eggs of
lizards sandy areas enlarged post maxilllary
teeth used to slit eggs (Elaphe)-Pantherophis-New
World forms Rat Snakes E. guttata
emoryi Great Plains Rat Snakes E.
obsoleta Western Rat Snake climbs trees,
attics etc. Lampropeltis L. triangulum- Milk
Snake - red on black bands L. calligaster-
Prairie King, - similar to G.P. rat snakes L.
getula- Speckled King, eat snakes King
Snakes Smooth scales on dorsum mostly non
venomous snakes Thelotornis African bird eating
snake, lethal Dispholidus - sub-Saharan
Africa boomslang, lethal, (rear-fanged) forest
dweller hemotoxic venom. (In 1957, well-known
herpetologist Karl Schmidt died after being
bitten by a boomslang.)
Dispholidus
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Subfamily Natricinae watersnakes Mostly eat
fish like to bite live birth Nerodia
erythrogaster - N. fasciata - N. sipedon -
Ozarks and Ouachitas, Midland Water snakes N.
rhombifer - most common, Diamondback,
defensively expand heads into diamond
shape N. cyclopion - Thamnophis T. sirtalis
- Garter Snake T. proximus - Ribbon
Snake Regina R. grahami - Graham's Crayfish
Snake R. septemvittata - Queen Snake, disjunct
distribution, Ozarks, no Queen snakes from Hot
Springs since 1890s, they are in Streams that
flow south out of the Boston Mts., Mulberry
River and Salado Creek, poorly known R. rigida
- So. AR in So. flowing streams, Gulf Glossy
Snake Virginia - Smooth earth snakes rough
earth snakes Storeria - Redbelly and brown
snakes Fitch-"Reproductive Cycles in Lizards and
Snakes" Fitch first entered biology with Oregon
Birds
Nerodia
Regina
Watersnake belly patterns
Storeria
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Subfamily Xenodontinae rear fanged Carphophis
amoenis helenae - on the Ridge, Worm Snake,
orange colored C. vermis-Western Worm
Snake Diadophis punctatus - Ringneck
Snake Mississippi Ringneck is heading into
Mts. Farancia - Mud Snakes eats sirens and
amphiumas, spine-like scale on the tip of the
tails, stinging snakes- gouge with
tail Heterodon -death feigning- flattens neck,
toad eaters Tantilla -Flathead Snake, our
smallest snake, eat lepidopteran and orthopteran
larvae, recently it has been placed in
Colubrinae, look like worms Snake
Facts! 2900 snakes in the world "Snakes in
Question" Ernst and Zug "Snakes" Greene
Hooknosed Sea snake is most venomous Enhydrina-
According to Ernst and Zug Greene says it is the
Australian Taipan (See slide at end of this
slide series for top venomous snakes)
Carphophis vermis
Heterodon platirhinos
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Family Elapidae Cobras, Kraits, Seasnakes, Death
Adders, and Allies 2 subfamilies 50 genera
295 species -usually front fanged
proteroglyphous -usually can "throw" venom
left lung absent large ventrals -tubular
hollow fangs neurotoxic venom shuts down
respiratory system Subfamily Elapinae Naja
- cobras common in the Old World some can
accurately spit into predators
eyes Ophiophagus hannah 18 ft largest
venomous snake king cobra feeds on other
snakes intelligent exceptionally aggressive
when guarding eggs feared and revered in many
cultures
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Dendroapsis mambas terrestrial to
arboreal defensive fastest of all
snakes mostly African 14 ft Bungarus kraits
forest floor more docile than most
Elapids Acanthophis short, stout
body triangular head lifestyle is similar to
viperids
Dendroapsis
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Coral Snakes -our representatives are only in
extreme south of Arkansas near Louisiana Micrurus
many in central America fossorial eat snakes
and lizards have rigid fangs at rear of the
mouth neurotoxins M. fulvius - Eastern coral
snake M. tener - Texas coral snake Micruroides
euryxanthus Arizona coral snake
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Subfamily Hydrophiinae most venomous some
terrestrial members mostly sea snakes 10 most
venomous snakes are these around Aus. Lauticauda
sea kraits between terrestrial and marine
hydrophiines comes to the shore to digest
marine food eats eels and the like
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Top 10 Venomous Snakes

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