Animal Biology & Behavior: Key Concepts in Zoology
Reptile Diversity & Evolution
Reptile Skull Classifications
Synapsids: Reptiles that had one hole in each temporal region. They eventually gave rise to modern mammals.
Anapsids: Reptiles that have a skull with no temporal holes.
Diapsids: Reptiles that have two holes in each temporal region, one above the other.
Modern Reptile Groups
- Turtles
- Sphenodonts (Tuataras)
- Snakes and Lizards
- Crocodilians
Avian Adaptations for Flight
Airfoil Design
An airfoil is curved down on the top and curved up on the bottom, generating lift for flight.
Theropod Bird Characteristics
Birds, evolved from theropod dinosaurs, exhibit several key characteristics:
- Hollow bones
- Fused collarbones that form a V-shaped wishbone
- Rearranged muscles in the hips and legs that improve bipedal movement
- Hands that have lost their fourth and fifth fingers
- Feathers
Principles of Flight
Successful flight in birds requires a combination of adaptations:
- Wings that produce lift for flight
- Strong flight muscles that move the wings
- An active metabolism that provides energy to the muscles
- Hollow bone structure for reduced weight
- Reproductive adaptations (e.g., laying eggs to reduce weight during flight)
Bird Ecological Niches
A bird’s ecological niche is often reflected in its physical characteristics, including:
- Wing shape
- Beak shape
- Foot shape
Mammalian Traits & Diversity
Defining Mammals
Mammals: Active, large-brained, endothermic animals with complex social, feeding, and reproductive behaviors. Key characteristics include:
- Mammary glands for milk production
- Hair or fur
- Middle ear containing three bones (malleus, incus, stapes)
- A specialized jaw that allows them to chew their food efficiently
Mammalian Subclasses
Monotremes: Mammals that lay eggs (e.g., platypus, echidna).
Marsupials: Mammals that give birth to immature, underdeveloped live young that grow to maturity inside a marsupium or pouch (e.g., kangaroos, opossums).
Eutherians: Mammals that give birth to live young that have completed fetal development within the uterus (placental mammals).
Fundamental Concepts in Animal Behavior
Behavioral Triggers & Responses
Stimulus: A type of information that has the potential to make an organism change its behavior.
Kinesis: An increase in random movement that lasts until a favorable environment is reached.
Taxis: A movement in a specific direction, either toward or away from a stimulus.
Biological Rhythms
Circadian Rhythm: A daily cycle of activity that occurs over a 24-hour period.
Biological Clock: Activity patterns are controlled by an internal mechanism, often synchronized with environmental cues.
Innate & Learned Behaviors
Instinct: An inborn behavior, genetically programmed.
Innate Behavior: A behavior performed correctly the first time it is tried, without prior learning.
Habituation: Occurs when an animal’s behavioral response decreases due to a repeated stimulus, even if it has features that would normally trigger innate behaviors.
Imprinting: A rapid and irreversible learning process that only occurs during a short, critical period in an animal’s life.
Imitation: Animals learn by observing other animals’ behavior.
Types of Conditioning
Classical Conditioning: A process in which an animal learns to associate a previously neutral stimulus with a behavior that was once triggered by a different stimulus (e.g., Pavlov’s dogs).
Operant Conditioning: A process in which the likelihood of a specific behavior is increased by reinforcement or decreased by punishment (e.g., Skinner box experiments).
Population Dynamics & Costs of Behavior
Survivorship: Refers to the number of individuals that survive from one year to the next within a population.
Costs of Behavior: Behaviors often come with associated costs:
- Energy cost (e.g., foraging, fighting)
- Opportunity costs (e.g., time spent on one activity means less time for another)
- Risk costs (e.g., exposure to predators)
Social Behavior & Communication
Territoriality: The control of a specific area by one or more individuals of an animal species, often defended against intruders.
Optimal Foraging: States that natural selection should favor behaviors that get animals the most, or optimal amount, of calories for the cost incurred.
Communication: Animals communicate using various modalities:
- Visual signals
- Sound (auditory)
- Touch (tactile)
- Chemical signals
Pheromones: Chemicals released by an animal that affect the behavior of other individuals of the same species.
Altruism & Social Structures
Altruism: A kind of behavior in which an animal reduces its own fitness to help other members of its social group.
Inclusive Fitness: The total number of genes an animal and its relatives contribute to the next generation, considering both direct offspring and relatives’ offspring.
Kin Selection: A form of natural selection that acts on alleles that favor the survival and reproduction of close relatives, even at a cost to the individual’s direct reproduction.
Eusocial Species: Species that live in large, complex social groups made up of many individuals, most of whom are non-reproductive workers or soldiers (e.g., ants, bees, termites).
Cognition & Learning
Cognition: The mental process of knowing through perception, reasoning, and understanding.
Insight: The ability to solve a problem mentally without repeated trial and error, often involving a sudden understanding.
Cultural Behavior: Behavior that is spread through a population by learning and transmission across generations, rather than solely by genetic selection.
Reproductive Strategies & Physiology
Reproductive Modes
Oviparous: Animals that deposit their eggs into an external nest or environment, where they develop and hatch (e.g., most birds, reptiles, amphibians).
Viviparous: Animals that hold eggs inside their body; once developed, the young hatch or are born live (e.g., most mammals, some reptiles and fish).
Thermoregulation
Ectotherms: Organisms whose body temperature is primarily determined by their surroundings (e.g., reptiles, amphibians, fish).
Endotherms: Organisms that use their own metabolic heat to keep their tissues warm, maintaining a relatively constant internal body temperature (e.g., mammals, birds).
Amniotic Egg Structures
The amniotic egg, a key adaptation for terrestrial life, contains several protective membranes:
- Amnion: Protects and surrounds the embryo in a fluid-filled sac.
- Chorion: Allows gas exchange with the outside environment.
- Allantois: Holds waste materials as the embryo grows.
- Yolk Sac: Contains the nutrient supply for the growing embryo.