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Herpetology
Prepared for Master Naturalist by: Sarah J. Baker
Illinois Natural History Survey
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying herps
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
What is a Herp?
• From latin word herpeton meaning “to crawl on belly”
• As defined by Linnaeus they are “abhorrent because of their cold body, pale color, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation, and terrible venom; wherefore their creator has not exerted his powers to make many of them”
What is a Herp?
What is a Herp?
• Why are amphibians and reptiles still grouped together?
– Tradition
– Some overall similarity between groups
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Natural History and Diversity
• Amphibians and reptiles share some characteristics:
– Tetrapods
– Ectothermy
– Single opening to digestive/urinary/reproductive system called cloaca
– Jacobson’s organ
Natural History and Diversity - Amphibians
• 3 orders (approx. 7,022 species)
– Anura (Frogs and Toads)
– Caudata (Salamanders)
– Gymnophiona (Caecilians)
• Distribution
– Nearly global!
Natural History and Diversity - Amphibians
• Common characteristics
– Thin permeable skin with mucus and toxin glands
– Metamorphosis
• Share similar ecological challenges
– Minimizing water loss
Natural History and Diversity – Anura
• 53 families - 6,196 species
• Highest diversity in the tropics
• Specialized anatomy
Natural History and Diversity – Anura
• External fertilization
• Bi-phasic life cycle with larval tadpole stage
• Variable time spent as tadpole
• Direct development occurs in some genera
Natural History and Diversity – Anura
• Metamorphosis – no easy task!
• During metamorphosis:
– Limbs are grown
– Tail and gills are lost
– Entire digestive system changes
Natural History and Diversity – Caudata
• 10 families – 635 species
• Highest diversity in the Appalachian region
• Many species also utilize a bi-phasic life cycle, although more variation in this theme is present in Caudata than Anura
– Direct development
– Eft stage of newts
Natural History and Diversity – Caudata
• Non-traditional stratagies:
– Neoteny/peadomorphisis
– Loss of lungs
– Communal nesting
Natural History and Diversity - Gymnophiona
• 10 families – 191 species
• Highest diversity in Central/South America
• Very little known about their life history
Natural History and Diversity – Reptiles
• Common characteristics:
– Tetrapod body design
– Amniotes
• 4 orders – approx. 9,547 species:
– Testudines (turtles and tortoises)
– Crocodylia (alligators and crocodiles)
– Squamata (lizards and snakes)
– Rhynchocephalia (tuataras)
Natural History and Diversity – Reptiles
• The Amniotic egg
Natural History and Diversity – Testudines
• 2 sub-orders - 14 families – 327 species
• Highest diversity in the SE USA and SE Asia
• Common characteristics
– Presence of a shell
– Lack of teeth
– Primitive skull morphology
Natural History and Diversity – Testudines
Natural History and Diversity – Testudines
Natural History and Diversity - Crocodylia
• 3 families – 25 species
• Tropical and sub-tropical distribution
• Only reptiles to show parental care
• All species are primarily aquatic
• Diapsid skull and 4 chambered heart
Natural History and Diversity - Squamata
• 65 families – 9,193 species
• Complicated phylogeny generally grouped into Lizards (5,634 species), Snakes (3,378 species), and Amphisbaenids (181 species)
• Diapsid skull (highly modified in snakes)
• Loss of limbs in multiple lineages
Natural History and Diversity - Squamata
Lizards
• Highest US diversity in SW
• 3 venomous species in 2 different families
• Adapted to all lifestyles from fossorial to semi-aquatic to arboreal
Natural History and Diversity - Squamata
Snakes
• Highest US diversity in the SE and SW
• Highly specialized body plan includes an extremely moveable skull and presence of only 1 functional lung. Some families/species have evolved specialized venom delivery systems
Fang Types
Opisthoglyphous Proteroglyphous Solenoglyphous
Natural History and Diversity - Squamata
Amphisbaenids
• “worm lizards”
• 6 families – 181 species
• Tropical to sub tropical distribution
Natural History and Diversity – Rhynchocephalia
Tuataras
• 1 family - 2 species
• Males lack copulatory organ
• Well developed parietal eye with small lens and retina on top of the head
• Distribution restricted to New Zealand
Functioning third eye
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Thermal Biology
• All herps are ectothermic
• ALL physiological processes closely tied to temperature
• Herps exhibit a wide range of behavioral temp regulation mechanisms
Thermal Biology
• Thermoregulation important in all herp groups
• Not all taxa have the same thermal requirements
– Amphibians generally function at lower temps
– Desert reptiles function well at higher temps
– Locomotor and physiological consequences for individuals not at optimal temp
Thermal Biology Coping with extremes
Extreme Cold
• Hibernation – Individual vs communal
– Juvenile vs adult
– Variable length of time
• Freeze tolerance – Painted Turtles
– Wood Frogs
Extreme Heat
• Aestivation – Used by many temperate
herps to conserve water/energy
– Western Spadefoot Toad
• Water Conservation – Waxy Frogs
– Cocoon building
Thermal Biology
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Foraging Modes
Sit and Wait
• Rely on crypsis
• Pros: – Little energy used
– Avoid detection by other predators
• Cons: – What if you choose a bad
spot?
Active
• Rely on speed
• Pros: – Can easily move to areas of
high prey density
• Cons: – Greater energy use
– Greater predator detection risk
Foraging Modes
• Used by:
– Frogs
– Vipers
– Large Turtles
– Alligators/Crocs
• Sit and Wait
Foraging Modes
• Active
– Used by:
• Many lizards
• Slender bodied constricting snakes
• Herbivorous turtles
Predator Defense Strategies
• Flight
• Crypsis
• Warning coloration
• Chemical Defense
• Specialized behaviors
– Death feigning
– Hissing/rattling
– Tail autotomy
Let’s take a quick break
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Locomotion
• Specializations in many herp taxa
• Hopping
– Bullfrogs can jump 4+ feet
– Skeletal modifications
– Tree frogs have toe pads for arboreal locomotion
Locomotion • Snakes
Locomotion
• Gliding
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Reproductive Modes
• Egg laying (oviparity) vs live bearing (viviparity)
– All turtles lay eggs
– All vipers give live birth (except 1)
– Some species switch between egg laying/live birth depending on latitude
Reproductive Modes
Egg laying
• Pros: – Less physically demanding to
female
• Cons: – Eggs vulnerable to predators
and weather events
Live bearing
• Pros: – Female able to regulate
incubation temp and avoid predators/weather events
• Cons: – Physically demanding for
female
– Potential increased predation risk for female
Reproductive Modes
• “Non-traditional” methods
– Parthenogenesis
• Pros and cons of asexual reproduction
– Polyploidy in IL salamanders
Reproductive Modes – Finding Mates • Anurans –
– Males call to attract females
– Females choose male with most impressive call
– Male calling rate and complexity increases when more males are present
– Amplexus and external fertilization
Reproductive Modes – Finding Mates
Reproductive Modes – Finding Mates
• Caudates
– Males court females with “dancing”
– Male deposits spermatophore which is picked up by female
Reproductive Modes – Finding Mates
• Testudines
– Live solitary lives and come together only for mating
– Males search for females
– Male red eared sliders and painted turtles have long claws used to tickle female
Reproductive Modes – Finding Mates
• Crocodylia
– Males compete for females
– Bellow to create “water dance”
– Female and male guard nest
Reproductive Modes- Finding Mates
• Squamata
– Males typically search for females
– Females may have multiple mates with multiple paternity within each clutch
– Males experience increased mortality while mate searching
Reproductive Modes
• Temperature dependent sex determination
– In crocs and turtles sex of offspring is determined by temperature eggs incubate
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Illinois Herp Diversity
• 102 native species
– Frogs and Toads (21 species)
– Salamanders (20 species)
– Turtles (17 species)
– Lizards (6 +1 species)
– Snakes (38 species)
Illinois Herp Diversity
• Illinois is conveniently positioned to include the easternmost range of some western species, the southern most range of northern species, the westernmost range of some eastern species, and the northernmost range of southern species
Illinois Herp Diversity
• Distribution of herps within the state is determined by habitat
• Generally, IL species can be divided into prairie and forest ecosystems
– Sand prairie is very rare with several endemic species in the state
Illinois Herp Diversity
• Venomous snakes
– 4 species: Copperhead, Cottonmouth, Timber Rattlesnake, Massasauga
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Conservation
• Threats to herps: habitat loss, invasive species, disease, commercial exploitation, environmental contamination, human persecution
• Habitat Loss – IL has lost >95% of wetlands and 99% of prairie in the state
Conservation • Invasive species
– Invasive plant species further threatening habitat
– No invasive herps in IL, 1 introduced lizard
Conservation
• Disease
• Herps can be indicator species
• Several herp diseases have been identified in IL in recent years
– Chytrid fungus
– Snake fungal disease - 2008
– Necrotizing fasciitis
– Ranavirus - 2013
Conservation
• Commercial Exploitation
– The taking of herps from wild populations for commerce
– Regulations vary by state
– No IL herp species are known to have declined due solely to commercial harvest
– Acquire pet herps from reputable breeders rather than wild populations
Conservation
• Environmental Contamination
• Biggest IL threat = pesticide exposure
– Can have consequences ranging from reduced immune response to endocrine system disruption
• Reduced immune response may play a role in disease outbreaks
– Massasaugas in IL have tested positive for lead
Conservation
• Human persecution
– Herps (esp. snakes) are not well liked by the general public
– Intentional and accidental human caused deaths can have big effects at the population level
– #1 killer is roads
• Studies have shown many people will intentionally run over snakes (or snake like objects) on roads
– Rattlesnake round-ups
Outline
• What is a “Herp”?
• Natural History and Diversity
• Thermal Biology
• Foraging Modes
• Locomotion
• Reproductive Modes
• Illinois Herp Diversity
• Conservation
• Finding and Identifying Herps
Finding Herps
• Visual Encounter Surveys
– Most common method used to find many species
– Walk around slowly, look at ground, flip cover objects when possible
– Pay attention to activity patterns of target species!
– Be sensitive to microhabitat conditions
– Know what species occur in your area and NEVER handle venomous snakes
Finding Herps
• Trapping
– Drift fence/pit fall traps
– Hoop traps for aquatic turtles
– Minnow traps for amphibians
– Dip nets
– Seines
Identifying Herps • Field Guides
• Dichotomous keys
Identifying Herps
• Though challenging at first knowing a few key features of each taxa can help you narrow down possible species quickly
– Plastron of turtles
– Smooth vs keeled scales and single vs divided anal plate in snakes
Identifying Herps
Feel free to contact me anytime with questions!
Contact Information:
Email: [email protected]
Office Phone: 217-300-4019