Reptile Notes

Reptiles

General Characteristics

  • Possess scales or scutes and dry skin; some have bony dermal plates composed of keratin.
  • Lack a larval stage and do not undergo metamorphosis.
  • Lay hard, leathery-shelled amniotic eggs, being the first group to do so.
  • Breathe through lungs.
  • Typically have legs with 3-5 toes and claws, except for legless lizards.
  • Ectothermic (cold-blooded).

General Characteristics (Continued)

  • Most have 3-chambered hearts, except crocodiles, which have 4-chambered hearts.
  • Possess keen sense organs.
  • Have forward-facing eyes.
  • Classified into 4 orders:
    • Sphenodontia: Tuataras, with only 2 species.
    • Testudines: Turtles and tortoises, with over 200 species.
    • Crocodilia: Crocodiles, caimans, and alligators, with 23 species.
    • Squamata: Lizards and snakes, with approximately 7900 species.

Tuatara - Sphenodon punctatus

  • Belongs to a distinct order (Rhynchocephalia) and is the only surviving species.
  • Not considered a lizard; classified as Diapsid.
  • Possesses a nictitating membrane (3rd eyelid).
  • Features a primitive skull structure.
  • Has a lizard-like appearance but is anatomically very different.
  • Considered a true "living fossil or dinosaur."
  • Found only on a few coastal New Zealand Islands with cool climates.
  • Lives in burrows.
  • Has a slow metabolism.

Tuatara Diet and Reproduction

  • Diet consists of insects, birds, lizards, arthropods, and worms.
  • Has 2 rows of teeth on top and 1 on the bottom.
  • Lacks external ears.
  • Has a slow reproductive cycle involving a cloacal kiss.
  • Females breed every 2-5 years, laying 5-19 eggs with a 12-15 month incubation period.
  • Reaches sexual maturity at 10-20 years.
  • Males lack external parts.
  • Can live up to 100 years.
  • Classified as an endangered and protected species.

Turtles – Generic Characteristics

  • Belong to the Order Testudines.
  • Evolved approximately 220 million years ago (mya).
  • Comprise around 225 species.
  • Lack teeth, possessing a beak instead.
  • Generally lead solitary lives.
  • Divided into 2 suborders based on how they retract their heads into their shells: Pleurodires and Cryptodires.
  • Classified into 3 types:
    • Terrestrial (tortoise or box turtle).
    • Aquatic and semi-aquatic (terrapins).
    • Marine (sea turtles).

Turtle Shell Characteristics

  • Possess a hard shell made of overgrown keratin.
  • The shell is composed of bone, skin, and scale, forming a sandwich-like structure.
  • The upper shell is called the Carapace.
  • The lower shell is called the Plastron.
  • The spine is fused to the shell.
  • Have well-developed senses.
  • Most are herbivores, while some are omnivores.

Marine Turtles

  • All 7 species are endangered or threatened.
  • Nest sites are being destroyed by human activities.
  • Diet ranges from sponges to seagrass and jellyfish.
  • Lay 50-150 eggs per batch on land; temperature determines the sex of hatchlings.
  • Live in warm waters and travel long distances.
  • Have large, streamlined shells.
  • Possess large front flippers and hind rudders; cannot retract flippers into the shell.

Terrapins

  • Aquatic or semi-aquatic turtles.
  • Hibernate (brumate) in water.
  • Live in fresh or brackish water.
  • Omnivores, consuming small fish, insects, and plants.
  • Have large webbed back feet.
  • Equally adept on land and in water.

Tortoises

  • Terrestrial turtles.
  • Have a high-domed shell/saddleback.
  • Possess column-like legs/feet.
  • Have claws for digging (5 on front feet, 4 on back feet).
  • Herbivores.
  • Can live for 100+ years.
  • Diurnal.
  • Inhabit various habitats: deserts, grasslands, and shrubby places.

Box Turtles & Tortoises

  • Tortoises are found in Africa and Madagascar (e.g., Sulcata, giant tortoise).
  • Box turtles are North American species.
  • The Ornate Box Turtle is the Kansas state reptile.
  • Include the 3-toed box turtle.

Turtle Examples

  • Sulcata Tortoise
  • Painted Turtle
  • Red-eared Slider
  • Snapping Turtle
  • Stinkpot
  • Three-Toed Box Turtle
  • Ornate Box Turtle
  • Western Painted Turtle
  • Red-Eared Slider
  • Soft Shell Turtle

Anatomy of a Turtle

  • Liver
  • Small intestine
  • Heart
  • Stomach

Sulcata Tortoise

  • Also known as the African spurred tortoise.

Lizards

  • Belong to the order Squamata, suborder Sauria.
  • Comprise around 3000 species.
  • Possess an external ear opening and moveable eyelids.
  • Most can readily detach and regenerate their tails.
  • Inhabit many different habitats.
  • Reproduce by egg-laying or live birth (no placenta).
  • Use tongues to aid in smelling.
  • Hibernate in colder climates.
  • Lack ears; eardrum located behind the eyes.
  • Store fat in their tails.
  • Run, climb, and cling; some can run on water.
  • Skin does not grow with size, shed instead.
  • Gestation period is around 12 months; most lay 5-20 eggs.
  • Change colors for thermoregulation or camouflage.
  • Examples: Anole, chameleon, bearded dragon.

Lizard Senses and Behavior

  • Have keen eyesight, moveable eyelids, and are visual hunters.
  • Possess a pineal eye receptive to sunlight and temperature, associated with the pineal gland.
  • Most are insectivores, but some are carnivores.
  • Males are territorial and display with head bobs and push-up displays.
  • Many are arboreal.
  • 3 species are poisonous:
    • Beaded dragon (Mexico).
    • Gila Monster (found only in the U.S.).
    • Komodo dragon (saliva is bacteria-infected).

Lizard Thermoregulation