Herpetology is the study of reptiles and amphibians
Why study herpetology?Important implications for conservation,research and education o Amphibians are excellent bio-indicators for environmental quality and change. o Snake venom is proving to be very useful to the medical field (dissolving blood clots in heart attack and stroke victims).
Types of Amphibians• Frogs• Toads• Salamanders• Caecilians
Amphibians as Bio-indicators•Because amphibians absorb waterthrough their skin, they are often thefirst to suffer the effects of water orenvironmental pollution.•Nearly 1/3 (32%) of amphibiansworldwide are threatened•Nearly 168 species are believed tohave gone extinct•43% of species are in decline
Major reasons for decline:•Habitat destruction•Chytridiomycosis (a fungal disease)Other factors:•Introduction of non-native species•Over-exploitation (pet trade)•Climate change; amphibians are very sensitive tosmall temperature changes, which can affect theirbreeding habits, reproduction and immune response•UV-B radiation (due to decreases in stratosphericozone layer)•Chemical contaminants (pesticides, heavy metals,acidification and nitrogen based fertilizers)
Amphibians: Means “double life”• Have gills and lungs• Are cold-blooded• Most lay soft, gel-covered eggs (exceptions include the Fire Salamander, some African Toads and most species of Caecilians)• Are vertebrates• Many have toxic secretions as defense
Common Salamanders ofShenandoah River State Park
Newts:• All newts are salamanders, but not all salamanders are newts.• Newts have three distinct life stages – Aquatic larvae (tadpole) – Terrestrial adult (eft): 1 to 3 years – Aquatic adult (newt)
Salamander Life Cycle Egg LarvaeAdult Juvenile
Salamander Biodiversity:• Salamanders can be aquatic, terrestrial, or a mixture of both. Living in diverse habitats cause different species to use different types of respiration.Types of Respiration:• External gills• Lungs• Skin/cutaneous respiration (all salamanders can do this)
Aquatic Habitat:• Larvae are born in water using external gills• Juveniles and adults breathe through external gills if retained, skin if not• Breathing through skin requires constant moisture, easy if aquatic (example: Mudpuppy)
Terrestrial Habitat:• Most terrestrial salamanders lay eggs in the water that hatch into aquatic larvae that later crawl out on land.• A few species lay eggs on land that hatch into juveniles.• Juveniles and Adults breathe through skin and lungs if present• If lungs are lacking the salamander must live in a moist area to breathe through its skin (ex.: Spotted Salamander)
Semi-Aquatic:•Larvae are born in water and breath throughexternal gills• Juveniles crawl out on land and breathe usinglungs.•Adults return to the water using skin to breathe,and occasionally venture on land using lungs.(example: Eastern Red Spotted Newt)
What they Eat: Mostly insects, however, any animal they can fit intheir mouth is fair game (including smaller salamanders!) Aquatic salamanders use chemical signals to track preyTerrestrial salamanders use vision to detect movementWhat Eats Them: Birds and snakes on land Fish and turtles in the water
Salamander eggs have a firm, outer jelly coating that encases the eggs.These are Spotted salamander eggs.
Common Frogs and Toads ofShenandoah River State Park
• Reptiles are vertebrates.• Reptiles are covered in scales or have scutes.• Reptiles breathe with lungs.• Most reptiles lay hard-shelled eggs. Some reptiles, like pit vipers, give birth to live young.• Almost all reptiles are cold-blooded. (One exception is the leatherback sea turtle, which can regulate its body temperature to some degree.)
Snake Characteristics• Snakes have clear scales over their eyes so they do not have eyelids forblinking or closing their eyes.•Snakes do not have ears so they do not hear as we do. They feelvibrations.•Snakes use their tongues for smelling using the Jacobson’s organ•The pits on venomous snakes detect thermal infrared radiation. Thepits respond to subtle thermal fluctuations in the environment andallows for an accurate measurement of the distance of a heat source.•Non-venomous snakes do not have fangs, but have rows of pointedbackward-curved teeth•A snake’s jaws can come apart so that they can eat large prey.•Snakes will shed their skin several times a year as they grow.
Turtle Characteristics• Do not have teeth• Usually omnivores• Lay eggs and leave them. Many eggs are eaten by predators, such as raccoons, skunks, coyotes, dogs, crows and snakes.• Box turtle populations are in decline due to habitat loss, road mortality and collection by humans.