Herpetology Lab Exam 2

Iowa State University BIOL 4570

Reptiles (Class Reptilia)

Reptiles (Class Reptilia)

• ectothermic (minus Aves)

• monophyletic group

• direct development (no larval stages) - gen 3-chambered hearts

• impermeable skin → breaks tie to water

• gas exchange in primarily lungs → breaks tie to water

• amniotic eggs (shelled eggs) → breaks tie to water

Snakes and Lizards (Order Squamata)

largest group of reptiles

• periodically shed skin/scales

• highly mobile skull/jaw

• paired copulatory organs: hemipenes

• jacobson organ

• multiple lineages without limbs

Squamata Suborders

Serpentes - snakes

Amphisbaenia - worm lizards

Lacertilia - lizards

Jaw Dentition/Anatomy

aglygolophus - no fangs

opisthoglyphous - rear fangs

proteroglyphous - front fixed

solenoglyphous - front hinged

Different Stages of Reproduction

viviparous - no eggs, internal fertilization, embryo develops with nutrients from placental connection → develop in mother, live birth of juveniles

ovoviviparous - mother lays eggs inside body, internal fertilization, eggs develop with nutrients from yolk to embryo → eggs hatch in mother, birth of juveniles

oviparous - mother lays eggs outside the body, internal/external fertilization, eggs develop with nutrients from yolk to embryo → eggs hatch, birth of juveniles

Suborder Serpentes

snakes- limbless or absence of limbs, no external ear or eyelid

2 in Iowa:

• Colubridae

• Viperidae

Not in Iowa

• Boidae

• Elapidae

Serpentes (snakes) Diagnostic Characteristics

1. presence of keeled scales

2. presence of divided anal plates

3. presence of lateral stripe

4. presence of fangs

5. color and pattern

additional traits: rostral scale upturned, labial scales

Family Colubridae (IA)

colurbirds

contains venomous and nonvenomous species

• scales are smooth and keeled

• anal plate single and divided

• left lung reduced'

• oviparous

• aglyphous (without fangs) and opisthoglyphous (rear fangs)

presence of keeled scales, divided anal plate, fang, lateral stripe and color and pattern

Thamnophis sirtails (IA)

common garter snake

• yellow lateral stripes on 2^nd and 3^rd scale rows

• black/brown, belly cream/gray with no pattern

• scales keeled, anal plate undivided

• labial scales mostly unmarked

Thamnophis radix (IA)

plains garter snake

• yellow lateral stripes on 3^rd and 4^th scale rows

• black/brown with alt rows of black spots, belly cream/gray with dark blotches down side

• scales keeled, anal plate undivided

• labial scales barred

Thamnophis proximus (IA)

western ribbon snake

• yellow lateral stripes on 3^rd and 4^th scale row with 2 small touching yellow dots on parietal scales

• black w/orange stripe down center back, belly light color with no pattern

• scales keeled, anal plate undivided

• labial scales unmarked

Thamnophis Differences

Tropidoclonion lineatum (IA)

lined snake

• olive brown with cream belly

• belly has 2 rows of black half-moons

• scales keeled, anal plate undivided

Storeria dekayii (IA)

northern brown snake

• brown/grey/reddish-brown, pale dorsal stripe

• dark stripe from behind eye to mouth

• scales keeled, anal plate divided

Storeria occipitomaculata (IA)

red-belly snake

• brown/grey/reddish brown, red ventral side (belly)

• pale dorsal stripe, no dark stripe from behind eye to mouth

• scales keeled, anal plate divided

Virginia valeriae (IA)

smooth earth snake

• brown/tan, white ventral (belly)

• pale dorsal stripe (not always), often NO markings

• scales smooth, anal plate divided

• pointed head

Carphophis vermis (IA)

western worm snake

• black/grey, belly pink/reddish color extends up to sides

• pointed head, small eyes

• scales smooth and glossy, anal plate divided

Opheodrys vernalis (IA)

smooth green snake

• green, brown/yellowish-green, white/pale yellow belly → hatchlings often a deeper green

• labials color of belly

• scales smooth, anal plate divided

Diadophis punctatus arnyi (IA)

prairie ring-necked snake

• shiny blue/black or grey, belly yellow/orange fades to red at tail

• yellow/orange ring around neck

• ventral has row of small spots

• scales smooth, anal plate divided

Regina grahamii (IA)

crayfish snake

• olive/brown, belly white/pale, matches labials

• ventral-lateral black zig-zag

• lateral stripe from ventral scales to ~ 4^th dorsal scale

• scales keeled, anal plate divided

Lampropeltis holbrook (IA)

speckled king snake

• black, belly yellow/white with clusters of black

• pale yellow speckling

• scales smooth, anal plate undivided

Lampropeltis triangulum (IA)

eastern milk snake

• grey/pale/dark background, belly white with clusters of black checkers

• red saddles with black outlines, row of black lateral spots

• back of head has a Y or V

• scales smooth, anal plate undivided

Lamporpeltis calligaster (IA)

prairie king snake

• olive/brown, belly cream/yellow with brown checkers

• brown saddles with black outlines, 2 oblong blotches on neck

• dark line from eye to angle of jaw

• scales weakly keeled, anal plate divided

Pantherophis ramspotti (IA)

western fox snake

• orange-tan, yellow background, belly yellow with black checkering

• brown/black saddles with alternating blotches, blotches become rings on tails

• scales weakly keeled, anal plate divided

Pantherophis obsoletus (IA)

western rat snake

• black/grey, neck/labial scales white, mid-belly black or brown, ventrals are bluish black

• pattern barely visible on adults, prominent on juveniles

• scales keeled, anal plate divided

Nerodia sipedon (IA)

northern water snake

• brown/grayish color, belly white with brown/red half moons

• light brown/reddish markings

• bands on neck that become blotches on back, smaller alternating spots on sides

• scales keeled, anal plate divided

Nerodia rhombifer (IA)

diamondback water snake

• greenish/olive/brown/tan, belly yellow/cream with half moons

• ‘diamond’ chain-like pattern on back, tail ringed

• large rectangular bars from ventral

• scales keeled, anal plate divided

Nerodia erythrogaster (IA)

plain belly water snake

• dark brown/black dorsal, unmarked

• belly orange/red, unmarked except dark pigment, labials match belly, might have dark lines

• scales keeled, anal plate divided

Coluber constrictor (IA)

north american racer

• black/gray with blue/yellow tones, belly cream/yellow, unmarked

• neck/throat yellow, upper labial scales white/yellow

• scales smooth, anal plate divided

Pituophis catenifer (IA)

gopher/bull snake

• white @neck, yellow/brown @mid, yellow tail, belly white/yellow with brown square/spots

• saddles with 3 color regions, labials are barred

• side scales tipped with brown/black

• scales keeled, anal plate undivided

Heterodon platirhinos (IA)

eastern hog-nosed snake

• olive/black/grey

• belly white, with light tail, light color labials

• can be spotted brown/yellow with darker brown spots

• paired dark neck spots

• scales keeled, anal plate divided

• enlarged rostral scale, slight upturn

Heterodon nasicus (IA)

plains hog-nosed snake

• tan w/dark brown blotches on back, belly shiny black with small yellow/white squares

• tail ventral black

• 2 alternating rows of small spots on sides, paired dark neck spots

• scales keeled, anal plate divided

• enlarged rostral scale, slight upturn

Habitat Preferences

arboreal: cryptic coloring, longer teeth, typically longer and slimmer

terrestrial: body shape often is correlated with activity level, → slender = moving constantly, thick = sedentary life

aquatic: laterally flattened tails for swimming

fossorial: a more compact head to dig with a defined rostral scale

Family Viperidae (IA)

presence of keeled scales, fangs and color and patterns. additional traits: vertical pupil, pits

• solenoglyphous (hinged fangs)

• sensory pits

• vertical pupils

• ovoviviparous

Crotalus horridus (IA)

timber rattlesnakes -highly venomous

• ground color variable, may be brown, yellow gray, with/out a rusty color dorsal stripe

• tail solid black with tan rattle

• thin black bands or chevrons on dorsal

• brown, broad postocular stripe

• scales keeled, anal plate undivided

• calm

• ovoviviparous

favor S/SW bluffs and rocky outcroppings with forest, overwinter with other snakes in hibernaculums

Crotalus viridis (IA)

prairie rattlesnake - highly venomous

• shades of brown from tan - greenish/dark brown, ventral cream/light yellow

• brown saddles, darker blotches down back, spots on side

• white thin postocular stripe

• scales keeled, anal plate undivided

• diurnal, nocturnal

• pugnacious - striking, feisty

open prairie areas, grassy plains

Sistrurus carenatus (IA)

eastern massasauga rattlesnake - highly venomous

• lighter brown/grey background, dark brown/black dorsal blotches outlined in white

• blotches turn into rings on tail, dark rattle

• black ventral with white/yellow irregular spots

• 2-3 rows of small spots on sides, brown, broad postocular stripe

• scales keeled, anal plate undivided

• diurnal (minus hot weather)

• ovoviviparous

• passive - slow to strike

rare in IA now, found in E IA. overwinter marshes, lakes, rivers, active grasslands, meadows, dry woodlands

Sistrurus tergeminus (IA)

western massasauga rattlesnake - highly venomous

• lighter brown/grey background, brown/olive saddles outlined in white

• blotches may turn into rings on tail

• vertical is black with irregular white/yellow

• brown, broad postocular stripe, 2-3 rows of small spots on side

• scales keeled, anal plate undivided

• diurnal

• ovoviviparous

• passive - slow to attack

rare in IA now, found in extreme SW . overwinter marshes, lakes, rivers, active grasslands, meadows, dry woodlands

Massasauga Rattlesnake differences

Agkistrodon contortrix

eastern copperhead - highly venomous

• bronze/tan background, brown/orange ‘hourglass’ saddles

• ventral is cream with dark patches

• brown, broad postocular stripe

• scales keeled (weakly) with single subcaudal scales, anal plate undivided

• active (until to hot day) nocturnal

• ovoviviparous

• passive - until restrained

rare in IA, found in extreme SE. overwinter rocky outcrops, active open rocky, wooded river or stream valleys

juveniles grey until first shed, also have sulfur yellow colored tail tip

Family Elapidae (NOT IA)

elapids

presence of fangs: and color and pattern.

asia, australia, africa, americas

habitats from arboreal - marine

• proteroglyphous (front fangs)

• mainly neurotoxic venom

• mostly oviparous

Family Boidae (NOT IA)

boas

presence of fangs

americas, asia, africa, europe

• some have labial pits

• constrictors

• ovoviviparous

maintain ancestral characteristics

• algyphous (no fangs)

• rigid lower jaw (akinetic skull)

• functional left lung

• vestigial pelvic girdle (spur)

• palatal teeth