Herpetology - University of Illinois Extensionweb.extension.illinois.edu/cfiv/downloads/61537.pdfHerpetology Prepared for Master Naturalist by: Sarah J. Baker Illinois Natural History

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



• Thermal Biology

• Foraging Modes

• Locomotion



• 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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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


• External fertilization

• Bi-phasic life cycle with larval tadpole stage

• Variable time spent as tadpole

• Direct development occurs in some genera


• 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


• 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 - Crocodylia


• 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


Lizards

• Highest US diversity in SW

• 3 venomous species in 2 different families

• Adapted to all lifestyles from fossorial to semi-aquatic to arboreal


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


Amphisbaenids

• “worm lizards”


• 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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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


• Caudates

– Males court females with “dancing”

– Male deposits spermatophore which is picked up by female


• 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


• 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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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 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


• 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


• Venomous snakes

– 4 species: Copperhead, Cottonmouth, Timber Rattlesnake, Massasauga

Outline



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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



• Thermal Biology

• Foraging Modes

• Locomotion



• Conservation


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

Documents

Herpetology - University of Illinois Extensionweb.extension.illinois.edu/cfiv/downloads/61537.pdfHerpetology Prepared for Master Naturalist by: Sarah J. Baker Illinois Natural History