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Burd BIOL 191 Study Guide – Lecture 16

Tetrapods

  • Definition: Tetrapods are vertebrate animals adapted for life on land.

  • Distinguishing Characteristics:

    • Limb structure: Four limbs used to support weight on land.

    • Musculoskeletal adaptations: Muscle force transmitted to limbs for movement.

    • Skeletal structure: Separation of the head from the shoulder girdle.

    • Frogs are noted for adaptations allowing them to live in trees or adapt to an underground lifestyle (fossorial).

Characteristics of Amphibians

  • Main Traits:

    • have Moist skin for gas exchange.

    • have Positive pressure lungs

    • have to gulp air into lungs

Gas Exchange in Amphibians

  • Amphibians exchange gases via skin (cutaneous respiration) and lungs.

  • Their moist skin facilitates gas exchange with the environment.

Buccal Pumping

  • Definition: A method of respiration:

    • Involves gulping air into the lungs.

    • Breathing process includes using cheek muscles to push air into the lungs.

Thermoregulation Terms

  • Ectothermic Organism: Animals that rely on external sources like sunlight for temperature regulation.

  • Endothermic Organism: Animals that maintain body temperature through internal sources, like mammals.

  • Poikilothermic Organism: Organisms with body temperature that varies according to the environment.

  • Homeothermic Organism: Organisms with a constant body temperature.

Amphibian Reproduction

  • Amphibians typically reproduce in wet environments.

  • Fertilization:

    • External Fertilization: Eggs fertilized outside the female's body (e.g., frogs).

    • Internal Fertilization: Sperm fertilizes eggs within the female's body.

Amphibians and Water Dependency for Reproduction

  • Many amphibians require moist conditions for egg laying to prevent desiccation.

Metamorphosis in Amphibians

  • Complete Metamorphosis: Involves major transformation from larval to adult form (e.g., tadpoles to frogs).

  • Direct Development: Eggs hatch into a juvenile form that resembles the adult, without a distinct larval stage.

Amphibian Diversity

  • Classes:

    • Anura: Frogs and toads, typically lack tails as adults.

    • Urodela: Salamanders and newts, characterized by tails.

    • Apoda: Caecilians, legless and worm-like amphibians.

Importance of Amphibians as Bioindicators

  • Sensitive to environmental changes, amphibians are good indicators of ecosystem health.

Amniotic Egg Adaptation

  • Definition: An egg structure allowing for reproduction on land, providing protection and nourishment to the embryo.

  • Components:

    • Amnion: Fluid-filled cavity providing cushioning.

    • Yolk Sac: Nutrient source for the developing embryo.

    • Albumen: Protects and provides water to the embryo.

    • Shell: Offers physical protection while allowing gas exchange.

Mammals and Amniotic Eggs

  • Some mammals, like monotremes (e.g., platypus), lay eggs, while most are viviparous (giving live birth).

Synapsids and Examples

  • Definition: A class of mammals characterized by the presence of single temporal fenestra.

  • Examples: Humans, cats, and dogs.

Diapsids and Examples

  • Definition: Reptiles characterized by two temporal fenestrae in their skull.

  • Examples: Birds, crocodiles, and lizards.

Anapsids

  • Definition: Reptiles with no temporal fenestrae (e.g., turtles).

Keratin in Reptiles

  • Keratin is found in scales and helps to protect against desiccation and abrasion.

Ectothermic vs. Endothermic in Reptiles

  • Most reptiles are ectothermic, regulating body temperature behaviorally (e.g., basking in the sun).

Lepidosaurs

  • Definition: A group of reptiles that includes lizards and snakes, characterized by overlapping scales.

Squamates

  • Characteristics include:

    • Movable eyelids.

    • External ear openings.

    • Diverse diet and habitats.

Jacobson's Organ

  • A sensory organ in reptiles used to detect chemical signals in the environment, enhancing their sense of smell.

Pit Vipers and Their Loreal Pits

  • Loreal pits are specialized structures in pit vipers used to detect infrared radiation, assisting in locating warm prey in low light conditions.

Archosaurs

  • Definition: A clade that includes birds and crocodilians, characterized by certain skull features and a derived ankle structure.

General Characteristics of Testudines (Turtles)

  • Protected by a hard shell composed of a carapace (upper) and plastron (lower).

  • Can withdraw their head and limbs into the shell for protection.

Difference Between Carapace and Plastron

  • Carapace: The dorsal shell covering the turtle’s body.

  • Plastron: The ventral shell covering the belly.

General Characteristics of Crocodilians

  • Aquatic adaptations.

  • Notable parental care behaviors.

  • Territorial and often solitary, hunting in groups under specific conditions.

  • Ectothermic metabolism allows for energy conservation in warmer aquatic environments.