Herpetology Exam Study Guide

Communication Modes

  • Acoustic:
    • Long-distance communication.
    • Unidirectional.
    • Easy to locate the source.
  • Visual:
    • Effective at short distances.
    • Obstructed by light levels and barriers.
  • Chemical:
    • Effective day and night.
    • Broadcasting can be inefficient unless the medium is moving.
  • Tactile:
    • Short-range communication.
    • Signals can be complex.

Salamander Communication

  • Dominated by chemical, visual, and tactile signals.
  • Use glands.
  • Rubbing and scratching.
  • Courtship displays.

Anuran Communication

  • Tadpoles chemically detect friends and foes.
  • Use color changes, body shape, throat movements, and foot waving.
  • Chorusing frogs individualize notes at the end of their songs.
  • They adjust timing to reduce interference with neighbors.
  • Fluid-filled chambers of the inner ear receive signals from the tympanic membrane.
  • Some frogs have lungs directly connected to the ear for extra sound detection.
  • Frog females sometimes duet with males.

Crocodilian Communication

  • Advertisement displays.
  • Aggression.
  • Courtship.
  • Baby calls.

Tuatara Communication

  • Head bobbing.
  • Throat swelling.
  • Mouth gaping.

Lizard Communication

  • Well-developed visual system.
  • Three-component chemosensory system.
  • Visual advertisements.
  • Chemical Communication:
    • Femoral glands: Smear lipid and protein secretions on rocks and substrate to mark territory.
    • Skin pheromones.
    • Scat odors.
    • Volmerolfaction.

Turtle Communication

  • Cloacal chemicals.
  • Sub-dentary glands.
  • Neglect auditory cues.
  • Visual communication is not very important.

Snake Communication

  • Tactile and chemosensory are most important.

Amphibian Reproduction

  • Sexual determination is genetic (gametes).
  • Exogenous hormones can alter the reproductive functions of frogs.
  • Atrazine (herbicide) turns male frogs into hermaphrodites.
  • Mediated by hormones, and environmental factors act as proximate cues.
  • External fertilization is ancestral for amphibians, but internal fertilization evolved in some frogs, most salamanders, and all caecilians.
  • Internal fertilization makes sperm competition more intense.

Amplexus Types

  • Inguinal: Males clasp female around waist (ancestral).
  • Axillary: Males clasp around the middle (frogs).
  • Cephalic: Dendrobatids.
  • Independent: Cloaca pressed together while facing different directions.
  • Straddle: Male sits on female’s head; sperm runs down female’s back.
  • Tailed frogs have two-way clasping when the “tail” is inserted into the female.

Lecithotrophy

  • Embryos receive all nutrients from the yolk of the egg.

Macrothermy

  • Embryos receive nutrients directly from thermy.

Egg Structure

  • Animal hemisphere: Less yolky material, contains the nucleus.
  • Mesolecithal: Moderate amounts of yolk permit only partial development of the embryo within the egg.
  • Macrolecithal: (Reptiles + Amphibians)
  • Hatching glands: Scattered over the snout and nape.

Salamander Eggs

  • Pond-breeding salamanders: Eggs are smaller than stream salamanders.
  • Stream-breeding salamanders: Larger eggs.
  • Non-aquatic eggs: Larger eggs than stream breeders for reduced surface area ratio.
  • Salamandrids can retain embryos in the oviduct.
  • Coldwater frogs lay eggs colonially with thick jelly coats.
  • Warmwater frogs lay eggs singly.
  • Flowing water frogs have larger eggs.
  • Some lay eggs in tiny pools to reduce predation (these eggs often have more yolk).

Forms of Frog Parental Care

  • Egg attendance.
  • Tadpole attendance.
  • Egg transport.
  • Froglet transport.
  • Development in the reproductive tract.

Amphibian Care

  • Predation prevention.
  • Egg aeration.
  • Bladder watering egg.
  • Egg movement.
  • Dispersal of young.

Caecilians

  • Lack a larval state.
  • Many caecilians are viviparous; young feed on oviduct material.

Salamander Larvae

  • Quiet water salamander larvae: Laterally compressed, with caudal fins that extend down the dorsal side. They possess an incised midventral gular fold.
  • Mountain stream salamander larvae: Gular fold with no indentation. Low fins.

Orton Tadpole Types

  • Dependent on opercular chamber structure.

Tadpole Morphology

  • Can modify morphology due to chemical cues of predators.

Turtle Eggs

  • Leather eggs: Vulnerable to desiccation (Squamates, some turtles).
  • Calcitic egg: Desiccation-resistant. Slower development!

Cold Torpor

  • Some hatchling turtles bury themselves below nests to resist winter temps.

Diapause

  • Hormonally controlled quiescence: Cessation of growth and metabolic activity.

Delayed Hatching

  • Can be used to wait for favorable conditions.

Turtle Courtship

  • Relies on vision and olfaction.
  • Male sea turtles use curved claws to clasp carapace during sex.

Snake Movement

  • The number of vertebrae increased, increasing the flexibility of the backbone.
  • Lateral undulation: S-shaped path on a surface with friction. Horizontal waves travel down the body in alternate waves, generating force at fixed points.
  • Slide pushing: S-shaped path on a surface with little friction. Body waves are generated very quickly.
  • Concertina: Army crawl, “Inchworming.” Static points of contact, can be used on low-friction surfaces.
  • Rectilinear: “Caterpillaring.”
  • Sidewinding: Sideways army crawling. Two points of contact.
  • The center of gravity must remain within a herp’s base of support to resist falling.

Footfall Patterns

  • Lateral footfall: (Most tetrapods) Forefoot falls following movement of the hindfoot.
  • Diagonal footfall: Forefoot follows the hindfoot of the opposite side.

Lizard Locomotion

  • Characterized by lateral bending of the vertebral axis.
  • Lizards possess an unusual joint between the pectoral girdle and the sternum.
  • Sprawling efficiency of lizards is enhanced by their weird tarsal bones and 5th metatarsal shape. Tarsal bones 1-4 are tightly bound together, and the 5th toe lies at an awkward angle to the others.

Crocodilian Locomotion

  • Vertebrae support strong axial muscles.
  • Sprawled position is used for rest, semi-erect for walking.

Turtle Locomotion

  • Lift the hindfoot before the opposite forelimb falls completely.
  • Asynchronous swimming: Hindlimbs for propulsion, forelimbs for orientation.
  • Synchronous swimming: Forelimbs generate thrust.

Snake Taxonomy

  • Leptotyphlopoidae: Thread snakes. Blind, toothless, and fossorial arthrovores.
  • Typhlopidae: Blind snakes. Fossorial scolecos with a shovel nose.
  • Uropeltidae: Shield-tailed snakes.
  • Xenopeltidae: Sunbeam snakes. Iridescent fossorial vertebrate eaters.
  • Loxocemidae: Mexico Burrowing Python. Nocturnal.
  • Acrochorididae: File snakes. Baggy rough skin, specialists of fish and crustaceans.

Lizard Taxonomy

  • Pygopodidae: Flap-footed lizard. Legless except for flaps near the vent.
  • Eublepharidae: Eyelid geckos. No toepads or functional eyelids.
  • Gekkonidae: Spectacled geckos. Usually adhesive toepads and fixed eyelids.
  • Cordylidae: Girdled lizards. Heavily armored and defensive.
  • Teiidae: Whiptails and racerunners. Active and diurnal.
  • Lacertidae: Wall lizards. Grandular small scales. Small active terrestrial lizards.
  • Anguidae: Alligator lizards. Armored and usually with reduced limbs.
  • Agamidae: Dragons. Often “frilly”.
  • Dactyloidae: Anoles. Small arboreal lizards with lamellae.